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1#
2# (C) Copyright 2000 - 2008
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# See file CREDITS for list of people who contributed to this
6# project.
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public License as
10# published by the Free Software Foundation; either version 2 of
11# the License, or (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program; if not, write to the Free Software
20# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21# MA 02111-1307 USA
22#
23
24Summary:
25========
26
27This directory contains the source code for U-Boot, a boot loader for
28Embedded boards based on PowerPC, ARM, MIPS and several other
29processors, which can be installed in a boot ROM and used to
30initialize and test the hardware or to download and run application
31code.
32
33The development of U-Boot is closely related to Linux: some parts of
34the source code originate in the Linux source tree, we have some
35header files in common, and special provision has been made to
36support booting of Linux images.
37
38Some attention has been paid to make this software easily
39configurable and extendable. For instance, all monitor commands are
40implemented with the same call interface, so that it's very easy to
41add new commands. Also, instead of permanently adding rarely used
42code (for instance hardware test utilities) to the monitor, you can
43load and run it dynamically.
44
45
46Status:
47=======
48
49In general, all boards for which a configuration option exists in the
50Makefile have been tested to some extent and can be considered
51"working". In fact, many of them are used in production systems.
52
53In case of problems see the CHANGELOG and CREDITS files to find out
54who contributed the specific port. The MAINTAINERS file lists board
55maintainers.
56
57
58Where to get help:
59==================
60
61In case you have questions about, problems with or contributions for
62U-Boot you should send a message to the U-Boot mailing list at
63<u-boot@lists.denx.de>. There is also an archive of previous traffic
64on the mailing list - please search the archive before asking FAQ's.
65Please see http://lists.denx.de/pipermail/u-boot and
66http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
67
68
69Where to get source code:
70=========================
71
72The U-Boot source code is maintained in the git repository at
73git://www.denx.de/git/u-boot.git ; you can browse it online at
74http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
75
76The "snapshot" links on this page allow you to download tarballs of
77any version you might be interested in. Official releases are also
78available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
79directory.
80
81Pre-built (and tested) images are available from
82ftp://ftp.denx.de/pub/u-boot/images/
83
84
85Where we come from:
86===================
87
88- start from 8xxrom sources
89- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
90- clean up code
91- make it easier to add custom boards
92- make it possible to add other [PowerPC] CPUs
93- extend functions, especially:
94  * Provide extended interface to Linux boot loader
95  * S-Record download
96  * network boot
97  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
98- create ARMBoot project (http://sourceforge.net/projects/armboot)
99- add other CPU families (starting with ARM)
100- create U-Boot project (http://sourceforge.net/projects/u-boot)
101- current project page: see http://www.denx.de/wiki/U-Boot
102
103
104Names and Spelling:
105===================
106
107The "official" name of this project is "Das U-Boot". The spelling
108"U-Boot" shall be used in all written text (documentation, comments
109in source files etc.). Example:
110
111        This is the README file for the U-Boot project.
112
113File names etc. shall be based on the string "u-boot". Examples:
114
115        include/asm-ppc/u-boot.h
116
117        #include <asm/u-boot.h>
118
119Variable names, preprocessor constants etc. shall be either based on
120the string "u_boot" or on "U_BOOT". Example:
121
122        U_BOOT_VERSION          u_boot_logo
123        IH_OS_U_BOOT            u_boot_hush_start
124
125
126Versioning:
127===========
128
129U-Boot uses a 3 level version number containing a version, a
130sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
131sub-version "34", and patchlevel "4".
132
133The patchlevel is used to indicate certain stages of development
134between released versions, i. e. officially released versions of
135U-Boot will always have a patchlevel of "0".
136
137
138Directory Hierarchy:
139====================
140
141- board         Board dependent files
142- common        Misc architecture independent functions
143- cpu           CPU specific files
144  - 74xx_7xx    Files specific to Freescale MPC74xx and 7xx CPUs
145  - arm720t     Files specific to ARM 720 CPUs
146  - arm920t     Files specific to ARM 920 CPUs
147    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
148    - imx       Files specific to Freescale MC9328 i.MX CPUs
149    - s3c24x0   Files specific to Samsung S3C24X0 CPUs
150  - arm925t     Files specific to ARM 925 CPUs
151  - arm926ejs   Files specific to ARM 926 CPUs
152  - arm1136     Files specific to ARM 1136 CPUs
153  - at32ap      Files specific to Atmel AVR32 AP CPUs
154  - i386        Files specific to i386 CPUs
155  - ixp         Files specific to Intel XScale IXP CPUs
156  - leon2       Files specific to Gaisler LEON2 SPARC CPU
157  - leon3       Files specific to Gaisler LEON3 SPARC CPU
158  - mcf52x2     Files specific to Freescale ColdFire MCF52x2 CPUs
159  - mcf5227x    Files specific to Freescale ColdFire MCF5227x CPUs
160  - mcf532x     Files specific to Freescale ColdFire MCF5329 CPUs
161  - mcf5445x    Files specific to Freescale ColdFire MCF5445x CPUs
162  - mcf547x_8x  Files specific to Freescale ColdFire MCF547x_8x CPUs
163  - mips        Files specific to MIPS CPUs
164  - mpc5xx      Files specific to Freescale MPC5xx  CPUs
165  - mpc5xxx     Files specific to Freescale MPC5xxx CPUs
166  - mpc8xx      Files specific to Freescale MPC8xx  CPUs
167  - mpc8220     Files specific to Freescale MPC8220 CPUs
168  - mpc824x     Files specific to Freescale MPC824x CPUs
169  - mpc8260     Files specific to Freescale MPC8260 CPUs
170  - mpc85xx     Files specific to Freescale MPC85xx CPUs
171  - nios        Files specific to Altera NIOS CPUs
172  - nios2       Files specific to Altera Nios-II CPUs
173  - ppc4xx      Files specific to AMCC PowerPC 4xx CPUs
174  - pxa         Files specific to Intel XScale PXA CPUs
175  - s3c44b0     Files specific to Samsung S3C44B0 CPUs
176  - sa1100      Files specific to Intel StrongARM SA1100 CPUs
177- disk          Code for disk drive partition handling
178- doc           Documentation (don't expect too much)
179- drivers       Commonly used device drivers
180- dtt           Digital Thermometer and Thermostat drivers
181- examples      Example code for standalone applications, etc.
182- include       Header Files
183- lib_arm       Files generic to ARM     architecture
184- lib_avr32     Files generic to AVR32   architecture
185- lib_generic   Files generic to all     architectures
186- lib_i386      Files generic to i386    architecture
187- lib_m68k      Files generic to m68k    architecture
188- lib_mips      Files generic to MIPS    architecture
189- lib_nios      Files generic to NIOS    architecture
190- lib_ppc       Files generic to PowerPC architecture
191- lib_sparc     Files generic to SPARC   architecture
192- libfdt        Library files to support flattened device trees
193- net           Networking code
194- post          Power On Self Test
195- rtc           Real Time Clock drivers
196- tools         Tools to build S-Record or U-Boot images, etc.
197
198Software Configuration:
199=======================
200
201Configuration is usually done using C preprocessor defines; the
202rationale behind that is to avoid dead code whenever possible.
203
204There are two classes of configuration variables:
205
206* Configuration _OPTIONS_:
207  These are selectable by the user and have names beginning with
208  "CONFIG_".
209
210* Configuration _SETTINGS_:
211  These depend on the hardware etc. and should not be meddled with if
212  you don't know what you're doing; they have names beginning with
213  "CFG_".
214
215Later we will add a configuration tool - probably similar to or even
216identical to what's used for the Linux kernel. Right now, we have to
217do the configuration by hand, which means creating some symbolic
218links and editing some configuration files. We use the TQM8xxL boards
219as an example here.
220
221
222Selection of Processor Architecture and Board Type:
223---------------------------------------------------
224
225For all supported boards there are ready-to-use default
226configurations available; just type "make <board_name>_config".
227
228Example: For a TQM823L module type:
229
230        cd u-boot
231        make TQM823L_config
232
233For the Cogent platform, you need to specify the CPU type as well;
234e.g. "make cogent_mpc8xx_config". And also configure the cogent
235directory according to the instructions in cogent/README.
236
237
238Configuration Options:
239----------------------
240
241Configuration depends on the combination of board and CPU type; all
242such information is kept in a configuration file
243"include/configs/<board_name>.h".
244
245Example: For a TQM823L module, all configuration settings are in
246"include/configs/TQM823L.h".
247
248
249Many of the options are named exactly as the corresponding Linux
250kernel configuration options. The intention is to make it easier to
251build a config tool - later.
252
253
254The following options need to be configured:
255
256- CPU Type:     Define exactly one, e.g. CONFIG_MPC85XX.
257
258- Board Type:   Define exactly one, e.g. CONFIG_MPC8540ADS.
259
260- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
261                Define exactly one, e.g. CONFIG_ATSTK1002
262
263- CPU Module Type: (if CONFIG_COGENT is defined)
264                Define exactly one of
265                CONFIG_CMA286_60_OLD
266--- FIXME --- not tested yet:
267                CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
268                CONFIG_CMA287_23, CONFIG_CMA287_50
269
270- Motherboard Type: (if CONFIG_COGENT is defined)
271                Define exactly one of
272                CONFIG_CMA101, CONFIG_CMA102
273
274- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
275                Define one or more of
276                CONFIG_CMA302
277
278- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
279                Define one or more of
280                CONFIG_LCD_HEARTBEAT    - update a character position on
281                                          the LCD display every second with
282                                          a "rotator" |\-/|\-/
283
284- Board flavour: (if CONFIG_MPC8260ADS is defined)
285                CONFIG_ADSTYPE
286                Possible values are:
287                        CFG_8260ADS     - original MPC8260ADS
288                        CFG_8266ADS     - MPC8266ADS
289                        CFG_PQ2FADS     - PQ2FADS-ZU or PQ2FADS-VR
290                        CFG_8272ADS     - MPC8272ADS
291
292- MPC824X Family Member (if CONFIG_MPC824X is defined)
293                Define exactly one of
294                CONFIG_MPC8240, CONFIG_MPC8245
295
296- 8xx CPU Options: (if using an MPC8xx CPU)
297                CONFIG_8xx_GCLK_FREQ    - deprecated: CPU clock if
298                                          get_gclk_freq() cannot work
299                                          e.g. if there is no 32KHz
300                                          reference PIT/RTC clock
301                CONFIG_8xx_OSCLK        - PLL input clock (either EXTCLK
302                                          or XTAL/EXTAL)
303
304- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
305                CFG_8xx_CPUCLK_MIN
306                CFG_8xx_CPUCLK_MAX
307                CONFIG_8xx_CPUCLK_DEFAULT
308                        See doc/README.MPC866
309
310                CFG_MEASURE_CPUCLK
311
312                Define this to measure the actual CPU clock instead
313                of relying on the correctness of the configured
314                values. Mostly useful for board bringup to make sure
315                the PLL is locked at the intended frequency. Note
316                that this requires a (stable) reference clock (32 kHz
317                RTC clock or CFG_8XX_XIN)
318
319- Intel Monahans options:
320                CFG_MONAHANS_RUN_MODE_OSC_RATIO
321
322                Defines the Monahans run mode to oscillator
323                ratio. Valid values are 8, 16, 24, 31. The core
324                frequency is this value multiplied by 13 MHz.
325
326                CFG_MONAHANS_TURBO_RUN_MODE_RATIO
327
328                Defines the Monahans turbo mode to oscillator
329                ratio. Valid values are 1 (default if undefined) and
330                2. The core frequency as calculated above is multiplied
331                by this value.
332
333- Linux Kernel Interface:
334                CONFIG_CLOCKS_IN_MHZ
335
336                U-Boot stores all clock information in Hz
337                internally. For binary compatibility with older Linux
338                kernels (which expect the clocks passed in the
339                bd_info data to be in MHz) the environment variable
340                "clocks_in_mhz" can be defined so that U-Boot
341                converts clock data to MHZ before passing it to the
342                Linux kernel.
343                When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
344                "clocks_in_mhz=1" is automatically included in the
345                default environment.
346
347                CONFIG_MEMSIZE_IN_BYTES         [relevant for MIPS only]
348
349                When transferring memsize parameter to linux, some versions
350                expect it to be in bytes, others in MB.
351                Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
352
353                CONFIG_OF_LIBFDT
354
355                New kernel versions are expecting firmware settings to be
356                passed using flattened device trees (based on open firmware
357                concepts).
358
359                CONFIG_OF_LIBFDT
360                 * New libfdt-based support
361                 * Adds the "fdt" command
362                 * The bootm command automatically updates the fdt
363
364                OF_CPU - The proper name of the cpus node.
365                OF_SOC - The proper name of the soc node.
366                OF_TBCLK - The timebase frequency.
367                OF_STDOUT_PATH - The path to the console device
368
369                boards with QUICC Engines require OF_QE to set UCC MAC
370                addresses
371
372                CONFIG_OF_BOARD_SETUP
373
374                Board code has addition modification that it wants to make
375                to the flat device tree before handing it off to the kernel
376
377                CONFIG_OF_BOOT_CPU
378
379                This define fills in the correct boot CPU in the boot
380                param header, the default value is zero if undefined.
381
382- Serial Ports:
383                CONFIG_PL010_SERIAL
384
385                Define this if you want support for Amba PrimeCell PL010 UARTs.
386
387                CONFIG_PL011_SERIAL
388
389                Define this if you want support for Amba PrimeCell PL011 UARTs.
390
391                CONFIG_PL011_CLOCK
392
393                If you have Amba PrimeCell PL011 UARTs, set this variable to
394                the clock speed of the UARTs.
395
396                CONFIG_PL01x_PORTS
397
398                If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
399                define this to a list of base addresses for each (supported)
400                port. See e.g. include/configs/versatile.h
401
402
403- Console Interface:
404                Depending on board, define exactly one serial port
405                (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
406                CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
407                console by defining CONFIG_8xx_CONS_NONE
408
409                Note: if CONFIG_8xx_CONS_NONE is defined, the serial
410                port routines must be defined elsewhere
411                (i.e. serial_init(), serial_getc(), ...)
412
413                CONFIG_CFB_CONSOLE
414                Enables console device for a color framebuffer. Needs following
415                defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
416                        VIDEO_FB_LITTLE_ENDIAN  graphic memory organisation
417                                                (default big endian)
418                        VIDEO_HW_RECTFILL       graphic chip supports
419                                                rectangle fill
420                                                (cf. smiLynxEM)
421                        VIDEO_HW_BITBLT         graphic chip supports
422                                                bit-blit (cf. smiLynxEM)
423                        VIDEO_VISIBLE_COLS      visible pixel columns
424                                                (cols=pitch)
425                        VIDEO_VISIBLE_ROWS      visible pixel rows
426                        VIDEO_PIXEL_SIZE        bytes per pixel
427                        VIDEO_DATA_FORMAT       graphic data format
428                                                (0-5, cf. cfb_console.c)
429                        VIDEO_FB_ADRS           framebuffer address
430                        VIDEO_KBD_INIT_FCT      keyboard int fct
431                                                (i.e. i8042_kbd_init())
432                        VIDEO_TSTC_FCT          test char fct
433                                                (i.e. i8042_tstc)
434                        VIDEO_GETC_FCT          get char fct
435                                                (i.e. i8042_getc)
436                        CONFIG_CONSOLE_CURSOR   cursor drawing on/off
437                                                (requires blink timer
438                                                cf. i8042.c)
439                        CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
440                        CONFIG_CONSOLE_TIME     display time/date info in
441                                                upper right corner
442                                                (requires CONFIG_CMD_DATE)
443                        CONFIG_VIDEO_LOGO       display Linux logo in
444                                                upper left corner
445                        CONFIG_VIDEO_BMP_LOGO   use bmp_logo.h instead of
446                                                linux_logo.h for logo.
447                                                Requires CONFIG_VIDEO_LOGO
448                        CONFIG_CONSOLE_EXTRA_INFO
449                                                additional board info beside
450                                                the logo
451
452                When CONFIG_CFB_CONSOLE is defined, video console is
453                default i/o. Serial console can be forced with
454                environment 'console=serial'.
455
456                When CONFIG_SILENT_CONSOLE is defined, all console
457                messages (by U-Boot and Linux!) can be silenced with
458                the "silent" environment variable. See
459                doc/README.silent for more information.
460
461- Console Baudrate:
462                CONFIG_BAUDRATE - in bps
463                Select one of the baudrates listed in
464                CFG_BAUDRATE_TABLE, see below.
465                CFG_BRGCLK_PRESCALE, baudrate prescale
466
467- Interrupt driven serial port input:
468                CONFIG_SERIAL_SOFTWARE_FIFO
469
470                PPC405GP only.
471                Use an interrupt handler for receiving data on the
472                serial port. It also enables using hardware handshake
473                (RTS/CTS) and UART's built-in FIFO. Set the number of
474                bytes the interrupt driven input buffer should have.
475
476                Leave undefined to disable this feature, including
477                disable the buffer and hardware handshake.
478
479- Console UART Number:
480                CONFIG_UART1_CONSOLE
481
482                AMCC PPC4xx only.
483                If defined internal UART1 (and not UART0) is used
484                as default U-Boot console.
485
486- Boot Delay:   CONFIG_BOOTDELAY - in seconds
487                Delay before automatically booting the default image;
488                set to -1 to disable autoboot.
489
490                See doc/README.autoboot for these options that
491                work with CONFIG_BOOTDELAY. None are required.
492                CONFIG_BOOT_RETRY_TIME
493                CONFIG_BOOT_RETRY_MIN
494                CONFIG_AUTOBOOT_KEYED
495                CONFIG_AUTOBOOT_PROMPT
496                CONFIG_AUTOBOOT_DELAY_STR
497                CONFIG_AUTOBOOT_STOP_STR
498                CONFIG_AUTOBOOT_DELAY_STR2
499                CONFIG_AUTOBOOT_STOP_STR2
500                CONFIG_ZERO_BOOTDELAY_CHECK
501                CONFIG_RESET_TO_RETRY
502
503- Autoboot Command:
504                CONFIG_BOOTCOMMAND
505                Only needed when CONFIG_BOOTDELAY is enabled;
506                define a command string that is automatically executed
507                when no character is read on the console interface
508                within "Boot Delay" after reset.
509
510                CONFIG_BOOTARGS
511                This can be used to pass arguments to the bootm
512                command. The value of CONFIG_BOOTARGS goes into the
513                environment value "bootargs".
514
515                CONFIG_RAMBOOT and CONFIG_NFSBOOT
516                The value of these goes into the environment as
517                "ramboot" and "nfsboot" respectively, and can be used
518                as a convenience, when switching between booting from
519                RAM and NFS.
520
521- Pre-Boot Commands:
522                CONFIG_PREBOOT
523
524                When this option is #defined, the existence of the
525                environment variable "preboot" will be checked
526                immediately before starting the CONFIG_BOOTDELAY
527                countdown and/or running the auto-boot command resp.
528                entering interactive mode.
529
530                This feature is especially useful when "preboot" is
531                automatically generated or modified. For an example
532                see the LWMON board specific code: here "preboot" is
533                modified when the user holds down a certain
534                combination of keys on the (special) keyboard when
535                booting the systems
536
537- Serial Download Echo Mode:
538                CONFIG_LOADS_ECHO
539                If defined to 1, all characters received during a
540                serial download (using the "loads" command) are
541                echoed back. This might be needed by some terminal
542                emulations (like "cu"), but may as well just take
543                time on others. This setting #define's the initial
544                value of the "loads_echo" environment variable.
545
546- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
547                CONFIG_KGDB_BAUDRATE
548                Select one of the baudrates listed in
549                CFG_BAUDRATE_TABLE, see below.
550
551- Monitor Functions:
552                Monitor commands can be included or excluded
553                from the build by using the #include files
554                "config_cmd_all.h" and #undef'ing unwanted
555                commands, or using "config_cmd_default.h"
556                and augmenting with additional #define's
557                for wanted commands.
558
559                The default command configuration includes all commands
560                except those marked below with a "*".
561
562                CONFIG_CMD_ASKENV       * ask for env variable
563                CONFIG_CMD_AUTOSCRIPT     Autoscript Support
564                CONFIG_CMD_BDI            bdinfo
565                CONFIG_CMD_BEDBUG       * Include BedBug Debugger
566                CONFIG_CMD_BMP          * BMP support
567                CONFIG_CMD_BSP          * Board specific commands
568                CONFIG_CMD_BOOTD          bootd
569                CONFIG_CMD_CACHE        * icache, dcache
570                CONFIG_CMD_CONSOLE        coninfo
571                CONFIG_CMD_DATE         * support for RTC, date/time...
572                CONFIG_CMD_DHCP         * DHCP support
573                CONFIG_CMD_DIAG         * Diagnostics
574                CONFIG_CMD_DOC          * Disk-On-Chip Support
575                CONFIG_CMD_DTT          * Digital Therm and Thermostat
576                CONFIG_CMD_ECHO           echo arguments
577                CONFIG_CMD_EEPROM       * EEPROM read/write support
578                CONFIG_CMD_ELF          * bootelf, bootvx
579                CONFIG_CMD_ENV            saveenv
580                CONFIG_CMD_FDC          * Floppy Disk Support
581                CONFIG_CMD_FAT          * FAT partition support
582                CONFIG_CMD_FDOS         * Dos diskette Support
583                CONFIG_CMD_FLASH          flinfo, erase, protect
584                CONFIG_CMD_FPGA           FPGA device initialization support
585                CONFIG_CMD_HWFLOW       * RTS/CTS hw flow control
586                CONFIG_CMD_I2C          * I2C serial bus support
587                CONFIG_CMD_IDE          * IDE harddisk support
588                CONFIG_CMD_IMI            iminfo
589                CONFIG_CMD_IMLS           List all found images
590                CONFIG_CMD_IMMAP        * IMMR dump support
591                CONFIG_CMD_IRQ          * irqinfo
592                CONFIG_CMD_ITEST          Integer/string test of 2 values
593                CONFIG_CMD_JFFS2        * JFFS2 Support
594                CONFIG_CMD_KGDB         * kgdb
595                CONFIG_CMD_LOADB          loadb
596                CONFIG_CMD_LOADS          loads
597                CONFIG_CMD_MEMORY         md, mm, nm, mw, cp, cmp, crc, base,
598                                          loop, loopw, mtest
599                CONFIG_CMD_MISC           Misc functions like sleep etc
600                CONFIG_CMD_MMC          * MMC memory mapped support
601                CONFIG_CMD_MII          * MII utility commands
602                CONFIG_CMD_NAND         * NAND support
603                CONFIG_CMD_NET            bootp, tftpboot, rarpboot
604                CONFIG_CMD_PCI          * pciinfo
605                CONFIG_CMD_PCMCIA               * PCMCIA support
606                CONFIG_CMD_PING         * send ICMP ECHO_REQUEST to network
607                                          host
608                CONFIG_CMD_PORTIO       * Port I/O
609                CONFIG_CMD_REGINFO      * Register dump
610                CONFIG_CMD_RUN            run command in env variable
611                CONFIG_CMD_SAVES        * save S record dump
612                CONFIG_CMD_SCSI         * SCSI Support
613                CONFIG_CMD_SDRAM        * print SDRAM configuration information
614                                          (requires CONFIG_CMD_I2C)
615                CONFIG_CMD_SETGETDCR      Support for DCR Register access
616                                          (4xx only)
617                CONFIG_CMD_SPI          * SPI serial bus support
618                CONFIG_CMD_USB          * USB support
619                CONFIG_CMD_VFD          * VFD support (TRAB)
620                CONFIG_CMD_CDP          * Cisco Discover Protocol support
621                CONFIG_CMD_FSL          * Microblaze FSL support
622
623
624                EXAMPLE: If you want all functions except of network
625                support you can write:
626
627                #include "config_cmd_all.h"
628                #undef CONFIG_CMD_NET
629
630        Other Commands:
631                fdt (flattened device tree) command: CONFIG_OF_LIBFDT
632
633        Note:   Don't enable the "icache" and "dcache" commands
634                (configuration option CONFIG_CMD_CACHE) unless you know
635                what you (and your U-Boot users) are doing. Data
636                cache cannot be enabled on systems like the 8xx or
637                8260 (where accesses to the IMMR region must be
638                uncached), and it cannot be disabled on all other
639                systems where we (mis-) use the data cache to hold an
640                initial stack and some data.
641
642
643                XXX - this list needs to get updated!
644
645- Watchdog:
646                CONFIG_WATCHDOG
647                If this variable is defined, it enables watchdog
648                support. There must be support in the platform specific
649                code for a watchdog. For the 8xx and 8260 CPUs, the
650                SIU Watchdog feature is enabled in the SYPCR
651                register.
652
653- U-Boot Version:
654                CONFIG_VERSION_VARIABLE
655                If this variable is defined, an environment variable
656                named "ver" is created by U-Boot showing the U-Boot
657                version as printed by the "version" command.
658                This variable is readonly.
659
660- Real-Time Clock:
661
662                When CONFIG_CMD_DATE is selected, the type of the RTC
663                has to be selected, too. Define exactly one of the
664                following options:
665
666                CONFIG_RTC_MPC8xx       - use internal RTC of MPC8xx
667                CONFIG_RTC_PCF8563      - use Philips PCF8563 RTC
668                CONFIG_RTC_MC13783      - use MC13783 RTC
669                CONFIG_RTC_MC146818     - use MC146818 RTC
670                CONFIG_RTC_DS1307       - use Maxim, Inc. DS1307 RTC
671                CONFIG_RTC_DS1337       - use Maxim, Inc. DS1337 RTC
672                CONFIG_RTC_DS1338       - use Maxim, Inc. DS1338 RTC
673                CONFIG_RTC_DS164x       - use Dallas DS164x RTC
674                CONFIG_RTC_ISL1208      - use Intersil ISL1208 RTC
675                CONFIG_RTC_MAX6900      - use Maxim, Inc. MAX6900 RTC
676                CFG_RTC_DS1337_NOOSC    - Turn off the OSC output for DS1337
677
678                Note that if the RTC uses I2C, then the I2C interface
679                must also be configured. See I2C Support, below.
680
681- Timestamp Support:
682
683                When CONFIG_TIMESTAMP is selected, the timestamp
684                (date and time) of an image is printed by image
685                commands like bootm or iminfo. This option is
686                automatically enabled when you select CONFIG_CMD_DATE .
687
688- Partition Support:
689                CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
690                and/or CONFIG_ISO_PARTITION
691
692                If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
693                CONFIG_CMD_SCSI) you must configure support for at
694                least one partition type as well.
695
696- IDE Reset method:
697                CONFIG_IDE_RESET_ROUTINE - this is defined in several
698                board configurations files but used nowhere!
699
700                CONFIG_IDE_RESET - is this is defined, IDE Reset will
701                be performed by calling the function
702                        ide_set_reset(int reset)
703                which has to be defined in a board specific file
704
705- ATAPI Support:
706                CONFIG_ATAPI
707
708                Set this to enable ATAPI support.
709
710- LBA48 Support
711                CONFIG_LBA48
712
713                Set this to enable support for disks larger than 137GB
714                Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
715                Whithout these , LBA48 support uses 32bit variables and will 'only'
716                support disks up to 2.1TB.
717
718                CFG_64BIT_LBA:
719                        When enabled, makes the IDE subsystem use 64bit sector addresses.
720                        Default is 32bit.
721
722- SCSI Support:
723                At the moment only there is only support for the
724                SYM53C8XX SCSI controller; define
725                CONFIG_SCSI_SYM53C8XX to enable it.
726
727                CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
728                CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
729                CFG_SCSI_MAX_LUN] can be adjusted to define the
730                maximum numbers of LUNs, SCSI ID's and target
731                devices.
732                CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
733
734- NETWORK Support (PCI):
735                CONFIG_E1000
736                Support for Intel 8254x gigabit chips.
737
738                CONFIG_E1000_FALLBACK_MAC
739                default MAC for empty EEPROM after production.
740
741                CONFIG_EEPRO100
742                Support for Intel 82557/82559/82559ER chips.
743                Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
744                write routine for first time initialisation.
745
746                CONFIG_TULIP
747                Support for Digital 2114x chips.
748                Optional CONFIG_TULIP_SELECT_MEDIA for board specific
749                modem chip initialisation (KS8761/QS6611).
750
751                CONFIG_NATSEMI
752                Support for National dp83815 chips.
753
754                CONFIG_NS8382X
755                Support for National dp8382[01] gigabit chips.
756
757- NETWORK Support (other):
758
759                CONFIG_DRIVER_LAN91C96
760                Support for SMSC's LAN91C96 chips.
761
762                        CONFIG_LAN91C96_BASE
763                        Define this to hold the physical address
764                        of the LAN91C96's I/O space
765
766                        CONFIG_LAN91C96_USE_32_BIT
767                        Define this to enable 32 bit addressing
768
769                CONFIG_DRIVER_SMC91111
770                Support for SMSC's LAN91C111 chip
771
772                        CONFIG_SMC91111_BASE
773                        Define this to hold the physical address
774                        of the device (I/O space)
775
776                        CONFIG_SMC_USE_32_BIT
777                        Define this if data bus is 32 bits
778
779                        CONFIG_SMC_USE_IOFUNCS
780                        Define this to use i/o functions instead of macros
781                        (some hardware wont work with macros)
782
783                CONFIG_DRIVER_SMC911X
784                Support for SMSC's LAN911x and LAN921x chips
785
786                        CONFIG_DRIVER_SMC911X_BASE
787                        Define this to hold the physical address
788                        of the device (I/O space)
789
790                        CONFIG_DRIVER_SMC911X_32_BIT
791                        Define this if data bus is 32 bits
792
793                        CONFIG_DRIVER_SMC911X_16_BIT
794                        Define this if data bus is 16 bits. If your processor
795                        automatically converts one 32 bit word to two 16 bit
796                        words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
797
798- USB Support:
799                At the moment only the UHCI host controller is
800                supported (PIP405, MIP405, MPC5200); define
801                CONFIG_USB_UHCI to enable it.
802                define CONFIG_USB_KEYBOARD to enable the USB Keyboard
803                and define CONFIG_USB_STORAGE to enable the USB
804                storage devices.
805                Note:
806                Supported are USB Keyboards and USB Floppy drives
807                (TEAC FD-05PUB).
808                MPC5200 USB requires additional defines:
809                        CONFIG_USB_CLOCK
810                                for 528 MHz Clock: 0x0001bbbb
811                        CONFIG_USB_CONFIG
812                                for differential drivers: 0x00001000
813                                for single ended drivers: 0x00005000
814                        CFG_USB_EVENT_POLL
815                                May be defined to allow interrupt polling
816                                instead of using asynchronous interrupts
817
818- USB Device:
819                Define the below if you wish to use the USB console.
820                Once firmware is rebuilt from a serial console issue the
821                command "setenv stdin usbtty; setenv stdout usbtty" and
822                attach your USB cable. The Unix command "dmesg" should print
823                it has found a new device. The environment variable usbtty
824                can be set to gserial or cdc_acm to enable your device to
825                appear to a USB host as a Linux gserial device or a
826                Common Device Class Abstract Control Model serial device.
827                If you select usbtty = gserial you should be able to enumerate
828                a Linux host by
829                # modprobe usbserial vendor=0xVendorID product=0xProductID
830                else if using cdc_acm, simply setting the environment
831                variable usbtty to be cdc_acm should suffice. The following
832                might be defined in YourBoardName.h
833
834                        CONFIG_USB_DEVICE
835                        Define this to build a UDC device
836
837                        CONFIG_USB_TTY
838                        Define this to have a tty type of device available to
839                        talk to the UDC device
840
841                        CFG_CONSOLE_IS_IN_ENV
842                        Define this if you want stdin, stdout &/or stderr to
843                        be set to usbtty.
844
845                        mpc8xx:
846                                CFG_USB_EXTC_CLK 0xBLAH
847                                Derive USB clock from external clock "blah"
848                                - CFG_USB_EXTC_CLK 0x02
849
850                                CFG_USB_BRG_CLK 0xBLAH
851                                Derive USB clock from brgclk
852                                - CFG_USB_BRG_CLK 0x04
853
854                If you have a USB-IF assigned VendorID then you may wish to
855                define your own vendor specific values either in BoardName.h
856                or directly in usbd_vendor_info.h. If you don't define
857                CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
858                CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
859                should pretend to be a Linux device to it's target host.
860
861                        CONFIG_USBD_MANUFACTURER
862                        Define this string as the name of your company for
863                        - CONFIG_USBD_MANUFACTURER "my company"
864
865                        CONFIG_USBD_PRODUCT_NAME
866                        Define this string as the name of your product
867                        - CONFIG_USBD_PRODUCT_NAME "acme usb device"
868
869                        CONFIG_USBD_VENDORID
870                        Define this as your assigned Vendor ID from the USB
871                        Implementors Forum. This *must* be a genuine Vendor ID
872                        to avoid polluting the USB namespace.
873                        - CONFIG_USBD_VENDORID 0xFFFF
874
875                        CONFIG_USBD_PRODUCTID
876                        Define this as the unique Product ID
877                        for your device
878                        - CONFIG_USBD_PRODUCTID 0xFFFF
879
880
881- MMC Support:
882                The MMC controller on the Intel PXA is supported. To
883                enable this define CONFIG_MMC. The MMC can be
884                accessed from the boot prompt by mapping the device
885                to physical memory similar to flash. Command line is
886                enabled with CONFIG_CMD_MMC. The MMC driver also works with
887                the FAT fs. This is enabled with CONFIG_CMD_FAT.
888
889- Journaling Flash filesystem support:
890                CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
891                CONFIG_JFFS2_NAND_DEV
892                Define these for a default partition on a NAND device
893
894                CFG_JFFS2_FIRST_SECTOR,
895                CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
896                Define these for a default partition on a NOR device
897
898                CFG_JFFS_CUSTOM_PART
899                Define this to create an own partition. You have to provide a
900                function struct part_info* jffs2_part_info(int part_num)
901
902                If you define only one JFFS2 partition you may also want to
903                #define CFG_JFFS_SINGLE_PART    1
904                to disable the command chpart. This is the default when you
905                have not defined a custom partition
906
907- Keyboard Support:
908                CONFIG_ISA_KEYBOARD
909
910                Define this to enable standard (PC-Style) keyboard
911                support
912
913                CONFIG_I8042_KBD
914                Standard PC keyboard driver with US (is default) and
915                GERMAN key layout (switch via environment 'keymap=de') support.
916                Export function i8042_kbd_init, i8042_tstc and i8042_getc
917                for cfb_console. Supports cursor blinking.
918
919- Video support:
920                CONFIG_VIDEO
921
922                Define this to enable video support (for output to
923                video).
924
925                CONFIG_VIDEO_CT69000
926
927                Enable Chips & Technologies 69000 Video chip
928
929                CONFIG_VIDEO_SMI_LYNXEM
930                Enable Silicon Motion SMI 712/710/810 Video chip. The
931                video output is selected via environment 'videoout'
932                (1 = LCD and 2 = CRT). If videoout is undefined, CRT is
933                assumed.
934
935                For the CT69000 and SMI_LYNXEM drivers, videomode is
936                selected via environment 'videomode'. Two different ways
937                are possible:
938                - "videomode=num"   'num' is a standard LiLo mode numbers.
939                Following standard modes are supported  (* is default):
940
941                      Colors    640x480 800x600 1024x768 1152x864 1280x1024
942                -------------+---------------------------------------------
943                      8 bits |  0x301*  0x303    0x305    0x161     0x307
944                     15 bits |  0x310   0x313    0x316    0x162     0x319
945                     16 bits |  0x311   0x314    0x317    0x163     0x31A
946                     24 bits |  0x312   0x315    0x318      ?       0x31B
947                -------------+---------------------------------------------
948                (i.e. setenv videomode 317; saveenv; reset;)
949
950                - "videomode=bootargs" all the video parameters are parsed
951                from the bootargs. (See drivers/video/videomodes.c)
952
953
954                CONFIG_VIDEO_SED13806
955                Enable Epson SED13806 driver. This driver supports 8bpp
956                and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
957                or CONFIG_VIDEO_SED13806_16BPP
958
959- Keyboard Support:
960                CONFIG_KEYBOARD
961
962                Define this to enable a custom keyboard support.
963                This simply calls drv_keyboard_init() which must be
964                defined in your board-specific files.
965                The only board using this so far is RBC823.
966
967- LCD Support:  CONFIG_LCD
968
969                Define this to enable LCD support (for output to LCD
970                display); also select one of the supported displays
971                by defining one of these:
972
973                CONFIG_ATMEL_LCD:
974
975                        HITACHI TX09D70VM1CCA, 3.5", 240x320.
976
977                CONFIG_NEC_NL6448AC33:
978
979                        NEC NL6448AC33-18. Active, color, single scan.
980
981                CONFIG_NEC_NL6448BC20
982
983                        NEC NL6448BC20-08. 6.5", 640x480.
984                        Active, color, single scan.
985
986                CONFIG_NEC_NL6448BC33_54
987
988                        NEC NL6448BC33-54. 10.4", 640x480.
989                        Active, color, single scan.
990
991                CONFIG_SHARP_16x9
992
993                        Sharp 320x240. Active, color, single scan.
994                        It isn't 16x9, and I am not sure what it is.
995
996                CONFIG_SHARP_LQ64D341
997
998                        Sharp LQ64D341 display, 640x480.
999                        Active, color, single scan.
1000
1001                CONFIG_HLD1045
1002
1003                        HLD1045 display, 640x480.
1004                        Active, color, single scan.
1005
1006                CONFIG_OPTREX_BW
1007
1008                        Optrex   CBL50840-2 NF-FW 99 22 M5
1009                        or
1010                        Hitachi  LMG6912RPFC-00T
1011                        or
1012                        Hitachi  SP14Q002
1013
1014                        320x240. Black & white.
1015
1016                Normally display is black on white background; define
1017                CFG_WHITE_ON_BLACK to get it inverted.
1018
1019- Splash Screen Support: CONFIG_SPLASH_SCREEN
1020
1021                If this option is set, the environment is checked for
1022                a variable "splashimage". If found, the usual display
1023                of logo, copyright and system information on the LCD
1024                is suppressed and the BMP image at the address
1025                specified in "splashimage" is loaded instead. The
1026                console is redirected to the "nulldev", too. This
1027                allows for a "silent" boot where a splash screen is
1028                loaded very quickly after power-on.
1029
1030- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1031
1032                If this option is set, additionally to standard BMP
1033                images, gzipped BMP images can be displayed via the
1034                splashscreen support or the bmp command.
1035
1036- Compression support:
1037                CONFIG_BZIP2
1038
1039                If this option is set, support for bzip2 compressed
1040                images is included. If not, only uncompressed and gzip
1041                compressed images are supported.
1042
1043                NOTE: the bzip2 algorithm requires a lot of RAM, so
1044                the malloc area (as defined by CFG_MALLOC_LEN) should
1045                be at least 4MB.
1046
1047                CONFIG_LZMA
1048
1049                If this option is set, support for lzma compressed
1050                images is included.
1051
1052                Note: The LZMA algorithm adds between 2 and 4KB of code and it
1053                requires an amount of dynamic memory that is given by the
1054                formula:
1055
1056                        (1846 + 768 << (lc + lp)) * sizeof(uint16)
1057
1058                Where lc and lp stand for, respectively, Literal context bits
1059                and Literal pos bits.
1060
1061                This value is upper-bounded by 14MB in the worst case. Anyway,
1062                for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1063                total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1064                a very small buffer.
1065
1066                Use the lzmainfo tool to determinate the lc and lp values and
1067                then calculate the amount of needed dynamic memory (ensuring
1068                the appropriate CFG_MALLOC_LEN value).
1069
1070- MII/PHY support:
1071                CONFIG_PHY_ADDR
1072
1073                The address of PHY on MII bus.
1074
1075                CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1076
1077                The clock frequency of the MII bus
1078
1079                CONFIG_PHY_GIGE
1080
1081                If this option is set, support for speed/duplex
1082                detection of gigabit PHY is included.
1083
1084                CONFIG_PHY_RESET_DELAY
1085
1086                Some PHY like Intel LXT971A need extra delay after
1087                reset before any MII register access is possible.
1088                For such PHY, set this option to the usec delay
1089                required. (minimum 300usec for LXT971A)
1090
1091                CONFIG_PHY_CMD_DELAY (ppc4xx)
1092
1093                Some PHY like Intel LXT971A need extra delay after
1094                command issued before MII status register can be read
1095
1096- Ethernet address:
1097                CONFIG_ETHADDR
1098                CONFIG_ETH2ADDR
1099                CONFIG_ETH3ADDR
1100
1101                Define a default value for Ethernet address to use
1102                for the respective Ethernet interface, in case this
1103                is not determined automatically.
1104
1105- IP address:
1106                CONFIG_IPADDR
1107
1108                Define a default value for the IP address to use for
1109                the default Ethernet interface, in case this is not
1110                determined through e.g. bootp.
1111
1112- Server IP address:
1113                CONFIG_SERVERIP
1114
1115                Defines a default value for the IP address of a TFTP
1116                server to contact when using the "tftboot" command.
1117
1118- Multicast TFTP Mode:
1119                CONFIG_MCAST_TFTP
1120
1121                Defines whether you want to support multicast TFTP as per
1122                rfc-2090; for example to work with atftp.  Lets lots of targets
1123                tftp down the same boot image concurrently.  Note: the Ethernet
1124                driver in use must provide a function: mcast() to join/leave a
1125                multicast group.
1126
1127                CONFIG_BOOTP_RANDOM_DELAY
1128- BOOTP Recovery Mode:
1129                CONFIG_BOOTP_RANDOM_DELAY
1130
1131                If you have many targets in a network that try to
1132                boot using BOOTP, you may want to avoid that all
1133                systems send out BOOTP requests at precisely the same
1134                moment (which would happen for instance at recovery
1135                from a power failure, when all systems will try to
1136                boot, thus flooding the BOOTP server. Defining
1137                CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1138                inserted before sending out BOOTP requests. The
1139                following delays are inserted then:
1140
1141                1st BOOTP request:      delay 0 ... 1 sec
1142                2nd BOOTP request:      delay 0 ... 2 sec
1143                3rd BOOTP request:      delay 0 ... 4 sec
1144                4th and following
1145                BOOTP requests:         delay 0 ... 8 sec
1146
1147- DHCP Advanced Options:
1148                You can fine tune the DHCP functionality by defining
1149                CONFIG_BOOTP_* symbols:
1150
1151                CONFIG_BOOTP_SUBNETMASK
1152                CONFIG_BOOTP_GATEWAY
1153                CONFIG_BOOTP_HOSTNAME
1154                CONFIG_BOOTP_NISDOMAIN
1155                CONFIG_BOOTP_BOOTPATH
1156                CONFIG_BOOTP_BOOTFILESIZE
1157                CONFIG_BOOTP_DNS
1158                CONFIG_BOOTP_DNS2
1159                CONFIG_BOOTP_SEND_HOSTNAME
1160                CONFIG_BOOTP_NTPSERVER
1161                CONFIG_BOOTP_TIMEOFFSET
1162                CONFIG_BOOTP_VENDOREX
1163
1164                CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1165                environment variable, not the BOOTP server.
1166
1167                CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1168                serverip from a DHCP server, it is possible that more
1169                than one DNS serverip is offered to the client.
1170                If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1171                serverip will be stored in the additional environment
1172                variable "dnsip2". The first DNS serverip is always
1173                stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1174                is defined.
1175
1176                CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1177                to do a dynamic update of a DNS server. To do this, they
1178                need the hostname of the DHCP requester.
1179                If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1180                of the "hostname" environment variable is passed as
1181                option 12 to the DHCP server.
1182
1183                CONFIG_BOOTP_DHCP_REQUEST_DELAY
1184
1185                A 32bit value in microseconds for a delay between
1186                receiving a "DHCP Offer" and sending the "DHCP Request".
1187                This fixes a problem with certain DHCP servers that don't
1188                respond 100% of the time to a "DHCP request". E.g. On an
1189                AT91RM9200 processor running at 180MHz, this delay needed
1190                to be *at least* 15,000 usec before a Windows Server 2003
1191                DHCP server would reply 100% of the time. I recommend at
1192                least 50,000 usec to be safe. The alternative is to hope
1193                that one of the retries will be successful but note that
1194                the DHCP timeout and retry process takes a longer than
1195                this delay.
1196
1197 - CDP Options:
1198                CONFIG_CDP_DEVICE_ID
1199
1200                The device id used in CDP trigger frames.
1201
1202                CONFIG_CDP_DEVICE_ID_PREFIX
1203
1204                A two character string which is prefixed to the MAC address
1205                of the device.
1206
1207                CONFIG_CDP_PORT_ID
1208
1209                A printf format string which contains the ascii name of
1210                the port. Normally is set to "eth%d" which sets
1211                eth0 for the first Ethernet, eth1 for the second etc.
1212
1213                CONFIG_CDP_CAPABILITIES
1214
1215                A 32bit integer which indicates the device capabilities;
1216                0x00000010 for a normal host which does not forwards.
1217
1218                CONFIG_CDP_VERSION
1219
1220                An ascii string containing the version of the software.
1221
1222                CONFIG_CDP_PLATFORM
1223
1224                An ascii string containing the name of the platform.
1225
1226                CONFIG_CDP_TRIGGER
1227
1228                A 32bit integer sent on the trigger.
1229
1230                CONFIG_CDP_POWER_CONSUMPTION
1231
1232                A 16bit integer containing the power consumption of the
1233                device in .1 of milliwatts.
1234
1235                CONFIG_CDP_APPLIANCE_VLAN_TYPE
1236
1237                A byte containing the id of the VLAN.
1238
1239- Status LED:   CONFIG_STATUS_LED
1240
1241                Several configurations allow to display the current
1242                status using a LED. For instance, the LED will blink
1243                fast while running U-Boot code, stop blinking as
1244                soon as a reply to a BOOTP request was received, and
1245                start blinking slow once the Linux kernel is running
1246                (supported by a status LED driver in the Linux
1247                kernel). Defining CONFIG_STATUS_LED enables this
1248                feature in U-Boot.
1249
1250- CAN Support:  CONFIG_CAN_DRIVER
1251
1252                Defining CONFIG_CAN_DRIVER enables CAN driver support
1253                on those systems that support this (optional)
1254                feature, like the TQM8xxL modules.
1255
1256- I2C Support:  CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1257
1258                These enable I2C serial bus commands. Defining either of
1259                (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1260                include the appropriate I2C driver for the selected CPU.
1261
1262                This will allow you to use i2c commands at the u-boot
1263                command line (as long as you set CONFIG_CMD_I2C in
1264                CONFIG_COMMANDS) and communicate with i2c based realtime
1265                clock chips. See common/cmd_i2c.c for a description of the
1266                command line interface.
1267
1268                CONFIG_I2C_CMD_TREE is a recommended option that places
1269                all I2C commands under a single 'i2c' root command.  The
1270                older 'imm', 'imd', 'iprobe' etc. commands are considered
1271                deprecated and may disappear in the future.
1272
1273                CONFIG_HARD_I2C selects a hardware I2C controller.
1274
1275                CONFIG_SOFT_I2C configures u-boot to use a software (aka
1276                bit-banging) driver instead of CPM or similar hardware
1277                support for I2C.
1278
1279                There are several other quantities that must also be
1280                defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1281
1282                In both cases you will need to define CFG_I2C_SPEED
1283                to be the frequency (in Hz) at which you wish your i2c bus
1284                to run and CFG_I2C_SLAVE to be the address of this node (ie
1285                the CPU's i2c node address).
1286
1287                Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1288                sets the CPU up as a master node and so its address should
1289                therefore be cleared to 0 (See, eg, MPC823e User's Manual
1290                p.16-473). So, set CFG_I2C_SLAVE to 0.
1291
1292                That's all that's required for CONFIG_HARD_I2C.
1293
1294                If you use the software i2c interface (CONFIG_SOFT_I2C)
1295                then the following macros need to be defined (examples are
1296                from include/configs/lwmon.h):
1297
1298                I2C_INIT
1299
1300                (Optional). Any commands necessary to enable the I2C
1301                controller or configure ports.
1302
1303                eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=  PB_SCL)
1304
1305                I2C_PORT
1306
1307                (Only for MPC8260 CPU). The I/O port to use (the code
1308                assumes both bits are on the same port). Valid values
1309                are 0..3 for ports A..D.
1310
1311                I2C_ACTIVE
1312
1313                The code necessary to make the I2C data line active
1314                (driven).  If the data line is open collector, this
1315                define can be null.
1316
1317                eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1318
1319                I2C_TRISTATE
1320
1321                The code necessary to make the I2C data line tri-stated
1322                (inactive).  If the data line is open collector, this
1323                define can be null.
1324
1325                eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1326
1327                I2C_READ
1328
1329                Code that returns TRUE if the I2C data line is high,
1330                FALSE if it is low.
1331
1332                eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1333
1334                I2C_SDA(bit)
1335
1336                If <bit> is TRUE, sets the I2C data line high. If it
1337                is FALSE, it clears it (low).
1338
1339                eg: #define I2C_SDA(bit) \
1340                        if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1341                        else    immr->im_cpm.cp_pbdat &= ~PB_SDA
1342
1343                I2C_SCL(bit)
1344
1345                If <bit> is TRUE, sets the I2C clock line high. If it
1346                is FALSE, it clears it (low).
1347
1348                eg: #define I2C_SCL(bit) \
1349                        if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1350                        else    immr->im_cpm.cp_pbdat &= ~PB_SCL
1351
1352                I2C_DELAY
1353
1354                This delay is invoked four times per clock cycle so this
1355                controls the rate of data transfer.  The data rate thus
1356                is 1 / (I2C_DELAY * 4). Often defined to be something
1357                like:
1358
1359                #define I2C_DELAY  udelay(2)
1360
1361                CFG_I2C_INIT_BOARD
1362
1363                When a board is reset during an i2c bus transfer
1364                chips might think that the current transfer is still
1365                in progress. On some boards it is possible to access
1366                the i2c SCLK line directly, either by using the
1367                processor pin as a GPIO or by having a second pin
1368                connected to the bus. If this option is defined a
1369                custom i2c_init_board() routine in boards/xxx/board.c
1370                is run early in the boot sequence.
1371
1372                CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1373
1374                This option enables configuration of bi_iic_fast[] flags
1375                in u-boot bd_info structure based on u-boot environment
1376                variable "i2cfast". (see also i2cfast)
1377
1378                CONFIG_I2C_MULTI_BUS
1379
1380                This option allows the use of multiple I2C buses, each of which
1381                must have a controller.  At any point in time, only one bus is
1382                active.  To switch to a different bus, use the 'i2c dev' command.
1383                Note that bus numbering is zero-based.
1384
1385                CFG_I2C_NOPROBES
1386
1387                This option specifies a list of I2C devices that will be skipped
1388                when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1389                command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1390                pairs.  Otherwise, specify a 1D array of device addresses
1391
1392                e.g.
1393                        #undef  CONFIG_I2C_MULTI_BUS
1394                        #define CFG_I2C_NOPROBES        {0x50,0x68}
1395
1396                will skip addresses 0x50 and 0x68 on a board with one I2C bus
1397
1398                        #define CONFIG_I2C_MULTI_BUS
1399                        #define CFG_I2C_MULTI_NOPROBES  {{0,0x50},{0,0x68},{1,0x54}}
1400
1401                will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1402
1403                CFG_SPD_BUS_NUM
1404
1405                If defined, then this indicates the I2C bus number for DDR SPD.
1406                If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1407
1408                CFG_RTC_BUS_NUM
1409
1410                If defined, then this indicates the I2C bus number for the RTC.
1411                If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1412
1413                CFG_DTT_BUS_NUM
1414
1415                If defined, then this indicates the I2C bus number for the DTT.
1416                If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1417
1418                CFG_I2C_DTT_ADDR:
1419
1420                If defined, specifies the I2C address of the DTT device.
1421                If not defined, then U-Boot uses predefined value for
1422                specified DTT device.
1423
1424                CONFIG_FSL_I2C
1425
1426                Define this option if you want to use Freescale's I2C driver in
1427                drivers/i2c/fsl_i2c.c.
1428
1429
1430- SPI Support:  CONFIG_SPI
1431
1432                Enables SPI driver (so far only tested with
1433                SPI EEPROM, also an instance works with Crystal A/D and
1434                D/As on the SACSng board)
1435
1436                CONFIG_SPI_X
1437
1438                Enables extended (16-bit) SPI EEPROM addressing.
1439                (symmetrical to CONFIG_I2C_X)
1440
1441                CONFIG_SOFT_SPI
1442
1443                Enables a software (bit-bang) SPI driver rather than
1444                using hardware support. This is a general purpose
1445                driver that only requires three general I/O port pins
1446                (two outputs, one input) to function. If this is
1447                defined, the board configuration must define several
1448                SPI configuration items (port pins to use, etc). For
1449                an example, see include/configs/sacsng.h.
1450
1451                CONFIG_HARD_SPI
1452
1453                Enables a hardware SPI driver for general-purpose reads
1454                and writes.  As with CONFIG_SOFT_SPI, the board configuration
1455                must define a list of chip-select function pointers.
1456                Currently supported on some MPC8xxx processors.  For an
1457                example, see include/configs/mpc8349emds.h.
1458
1459                CONFIG_MXC_SPI
1460
1461                Enables the driver for the SPI controllers on i.MX and MXC
1462                SoCs. Currently only i.MX31 is supported.
1463
1464- FPGA Support: CONFIG_FPGA
1465
1466                Enables FPGA subsystem.
1467
1468                CONFIG_FPGA_<vendor>
1469
1470                Enables support for specific chip vendors.
1471                (ALTERA, XILINX)
1472
1473                CONFIG_FPGA_<family>
1474
1475                Enables support for FPGA family.
1476                (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1477
1478                CONFIG_FPGA_COUNT
1479
1480                Specify the number of FPGA devices to support.
1481
1482                CFG_FPGA_PROG_FEEDBACK
1483
1484                Enable printing of hash marks during FPGA configuration.
1485
1486                CFG_FPGA_CHECK_BUSY
1487
1488                Enable checks on FPGA configuration interface busy
1489                status by the configuration function. This option
1490                will require a board or device specific function to
1491                be written.
1492
1493                CONFIG_FPGA_DELAY
1494
1495                If defined, a function that provides delays in the FPGA
1496                configuration driver.
1497
1498                CFG_FPGA_CHECK_CTRLC
1499                Allow Control-C to interrupt FPGA configuration
1500
1501                CFG_FPGA_CHECK_ERROR
1502
1503                Check for configuration errors during FPGA bitfile
1504                loading. For example, abort during Virtex II
1505                configuration if the INIT_B line goes low (which
1506                indicated a CRC error).
1507
1508                CFG_FPGA_WAIT_INIT
1509
1510                Maximum time to wait for the INIT_B line to deassert
1511                after PROB_B has been deasserted during a Virtex II
1512                FPGA configuration sequence. The default time is 500
1513                ms.
1514
1515                CFG_FPGA_WAIT_BUSY
1516
1517                Maximum time to wait for BUSY to deassert during
1518                Virtex II FPGA configuration. The default is 5 ms.
1519
1520                CFG_FPGA_WAIT_CONFIG
1521
1522                Time to wait after FPGA configuration. The default is
1523                200 ms.
1524
1525- Configuration Management:
1526                CONFIG_IDENT_STRING
1527
1528                If defined, this string will be added to the U-Boot
1529                version information (U_BOOT_VERSION)
1530
1531- Vendor Parameter Protection:
1532
1533                U-Boot considers the values of the environment
1534                variables "serial#" (Board Serial Number) and
1535                "ethaddr" (Ethernet Address) to be parameters that
1536                are set once by the board vendor / manufacturer, and
1537                protects these variables from casual modification by
1538                the user. Once set, these variables are read-only,
1539                and write or delete attempts are rejected. You can
1540                change this behaviour:
1541
1542                If CONFIG_ENV_OVERWRITE is #defined in your config
1543                file, the write protection for vendor parameters is
1544                completely disabled. Anybody can change or delete
1545                these parameters.
1546
1547                Alternatively, if you #define _both_ CONFIG_ETHADDR
1548                _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1549                Ethernet address is installed in the environment,
1550                which can be changed exactly ONCE by the user. [The
1551                serial# is unaffected by this, i. e. it remains
1552                read-only.]
1553
1554- Protected RAM:
1555                CONFIG_PRAM
1556
1557                Define this variable to enable the reservation of
1558                "protected RAM", i. e. RAM which is not overwritten
1559                by U-Boot. Define CONFIG_PRAM to hold the number of
1560                kB you want to reserve for pRAM. You can overwrite
1561                this default value by defining an environment
1562                variable "pram" to the number of kB you want to
1563                reserve. Note that the board info structure will
1564                still show the full amount of RAM. If pRAM is
1565                reserved, a new environment variable "mem" will
1566                automatically be defined to hold the amount of
1567                remaining RAM in a form that can be passed as boot
1568                argument to Linux, for instance like that:
1569
1570                        setenv bootargs ... mem=\${mem}
1571                        saveenv
1572
1573                This way you can tell Linux not to use this memory,
1574                either, which results in a memory region that will
1575                not be affected by reboots.
1576
1577                *WARNING* If your board configuration uses automatic
1578                detection of the RAM size, you must make sure that
1579                this memory test is non-destructive. So far, the
1580                following board configurations are known to be
1581                "pRAM-clean":
1582
1583                        ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1584                        HERMES, IP860, RPXlite, LWMON, LANTEC,
1585                        PCU_E, FLAGADM, TQM8260
1586
1587- Error Recovery:
1588                CONFIG_PANIC_HANG
1589
1590                Define this variable to stop the system in case of a
1591                fatal error, so that you have to reset it manually.
1592                This is probably NOT a good idea for an embedded
1593                system where you want the system to reboot
1594                automatically as fast as possible, but it may be
1595                useful during development since you can try to debug
1596                the conditions that lead to the situation.
1597
1598                CONFIG_NET_RETRY_COUNT
1599
1600                This variable defines the number of retries for
1601                network operations like ARP, RARP, TFTP, or BOOTP
1602                before giving up the operation. If not defined, a
1603                default value of 5 is used.
1604
1605                CONFIG_ARP_TIMEOUT
1606
1607                Timeout waiting for an ARP reply in milliseconds.
1608
1609- Command Interpreter:
1610                CONFIG_AUTO_COMPLETE
1611
1612                Enable auto completion of commands using TAB.
1613
1614                Note that this feature has NOT been implemented yet
1615                for the "hush" shell.
1616
1617
1618                CFG_HUSH_PARSER
1619
1620                Define this variable to enable the "hush" shell (from
1621                Busybox) as command line interpreter, thus enabling
1622                powerful command line syntax like
1623                if...then...else...fi conditionals or `&&' and '||'
1624                constructs ("shell scripts").
1625
1626                If undefined, you get the old, much simpler behaviour
1627                with a somewhat smaller memory footprint.
1628
1629
1630                CFG_PROMPT_HUSH_PS2
1631
1632                This defines the secondary prompt string, which is
1633                printed when the command interpreter needs more input
1634                to complete a command. Usually "> ".
1635
1636        Note:
1637
1638                In the current implementation, the local variables
1639                space and global environment variables space are
1640                separated. Local variables are those you define by
1641                simply typing `name=value'. To access a local
1642                variable later on, you have write `$name' or
1643                `${name}'; to execute the contents of a variable
1644                directly type `$name' at the command prompt.
1645
1646                Global environment variables are those you use
1647                setenv/printenv to work with. To run a command stored
1648                in such a variable, you need to use the run command,
1649                and you must not use the '$' sign to access them.
1650
1651                To store commands and special characters in a
1652                variable, please use double quotation marks
1653                surrounding the whole text of the variable, instead
1654                of the backslashes before semicolons and special
1655                symbols.
1656
1657- Commandline Editing and History:
1658                CONFIG_CMDLINE_EDITING
1659
1660                Enable editing and History functions for interactive
1661                commandline input operations
1662
1663- Default Environment:
1664                CONFIG_EXTRA_ENV_SETTINGS
1665
1666                Define this to contain any number of null terminated
1667                strings (variable = value pairs) that will be part of
1668                the default environment compiled into the boot image.
1669
1670                For example, place something like this in your
1671                board's config file:
1672
1673                #define CONFIG_EXTRA_ENV_SETTINGS \
1674                        "myvar1=value1\0" \
1675                        "myvar2=value2\0"
1676
1677                Warning: This method is based on knowledge about the
1678                internal format how the environment is stored by the
1679                U-Boot code. This is NOT an official, exported
1680                interface! Although it is unlikely that this format
1681                will change soon, there is no guarantee either.
1682                You better know what you are doing here.
1683
1684                Note: overly (ab)use of the default environment is
1685                discouraged. Make sure to check other ways to preset
1686                the environment like the autoscript function or the
1687                boot command first.
1688
1689- DataFlash Support:
1690                CONFIG_HAS_DATAFLASH
1691
1692                Defining this option enables DataFlash features and
1693                allows to read/write in Dataflash via the standard
1694                commands cp, md...
1695
1696- SystemACE Support:
1697                CONFIG_SYSTEMACE
1698
1699                Adding this option adds support for Xilinx SystemACE
1700                chips attached via some sort of local bus. The address
1701                of the chip must also be defined in the
1702                CFG_SYSTEMACE_BASE macro. For example:
1703
1704                #define CONFIG_SYSTEMACE
1705                #define CFG_SYSTEMACE_BASE 0xf0000000
1706
1707                When SystemACE support is added, the "ace" device type
1708                becomes available to the fat commands, i.e. fatls.
1709
1710- TFTP Fixed UDP Port:
1711                CONFIG_TFTP_PORT
1712
1713                If this is defined, the environment variable tftpsrcp
1714                is used to supply the TFTP UDP source port value.
1715                If tftpsrcp isn't defined, the normal pseudo-random port
1716                number generator is used.
1717
1718                Also, the environment variable tftpdstp is used to supply
1719                the TFTP UDP destination port value.  If tftpdstp isn't
1720                defined, the normal port 69 is used.
1721
1722                The purpose for tftpsrcp is to allow a TFTP server to
1723                blindly start the TFTP transfer using the pre-configured
1724                target IP address and UDP port. This has the effect of
1725                "punching through" the (Windows XP) firewall, allowing
1726                the remainder of the TFTP transfer to proceed normally.
1727                A better solution is to properly configure the firewall,
1728                but sometimes that is not allowed.
1729
1730- Show boot progress:
1731                CONFIG_SHOW_BOOT_PROGRESS
1732
1733                Defining this option allows to add some board-
1734                specific code (calling a user-provided function
1735                "show_boot_progress(int)") that enables you to show
1736                the system's boot progress on some display (for
1737                example, some LED's) on your board. At the moment,
1738                the following checkpoints are implemented:
1739
1740Legacy uImage format:
1741
1742  Arg   Where                   When
1743    1   common/cmd_bootm.c      before attempting to boot an image
1744   -1   common/cmd_bootm.c      Image header has bad     magic number
1745    2   common/cmd_bootm.c      Image header has correct magic number
1746   -2   common/cmd_bootm.c      Image header has bad     checksum
1747    3   common/cmd_bootm.c      Image header has correct checksum
1748   -3   common/cmd_bootm.c      Image data   has bad     checksum
1749    4   common/cmd_bootm.c      Image data   has correct checksum
1750   -4   common/cmd_bootm.c      Image is for unsupported architecture
1751    5   common/cmd_bootm.c      Architecture check OK
1752   -5   common/cmd_bootm.c      Wrong Image Type (not kernel, multi)
1753    6   common/cmd_bootm.c      Image Type check OK
1754   -6   common/cmd_bootm.c      gunzip uncompression error
1755   -7   common/cmd_bootm.c      Unimplemented compression type
1756    7   common/cmd_bootm.c      Uncompression OK
1757    8   common/cmd_bootm.c      No uncompress/copy overwrite error
1758   -9   common/cmd_bootm.c      Unsupported OS (not Linux, BSD, VxWorks, QNX)
1759
1760    9   common/image.c          Start initial ramdisk verification
1761  -10   common/image.c          Ramdisk header has bad     magic number
1762  -11   common/image.c          Ramdisk header has bad     checksum
1763   10   common/image.c          Ramdisk header is OK
1764  -12   common/image.c          Ramdisk data   has bad     checksum
1765   11   common/image.c          Ramdisk data   has correct checksum
1766   12   common/image.c          Ramdisk verification complete, start loading
1767  -13   common/image.c          Wrong Image Type (not PPC Linux ramdisk)
1768   13   common/image.c          Start multifile image verification
1769   14   common/image.c          No initial ramdisk, no multifile, continue.
1770
1771   15   lib_<arch>/bootm.c      All preparation done, transferring control to OS
1772
1773  -30   lib_ppc/board.c         Fatal error, hang the system
1774  -31   post/post.c             POST test failed, detected by post_output_backlog()
1775  -32   post/post.c             POST test failed, detected by post_run_single()
1776
1777   34   common/cmd_doc.c        before loading a Image from a DOC device
1778  -35   common/cmd_doc.c        Bad usage of "doc" command
1779   35   common/cmd_doc.c        correct usage of "doc" command
1780  -36   common/cmd_doc.c        No boot device
1781   36   common/cmd_doc.c        correct boot device
1782  -37   common/cmd_doc.c        Unknown Chip ID on boot device
1783   37   common/cmd_doc.c        correct chip ID found, device available
1784  -38   common/cmd_doc.c        Read Error on boot device
1785   38   common/cmd_doc.c        reading Image header from DOC device OK
1786  -39   common/cmd_doc.c        Image header has bad magic number
1787   39   common/cmd_doc.c        Image header has correct magic number
1788  -40   common/cmd_doc.c        Error reading Image from DOC device
1789   40   common/cmd_doc.c        Image header has correct magic number
1790   41   common/cmd_ide.c        before loading a Image from a IDE device
1791  -42   common/cmd_ide.c        Bad usage of "ide" command
1792   42   common/cmd_ide.c        correct usage of "ide" command
1793  -43   common/cmd_ide.c        No boot device
1794   43   common/cmd_ide.c        boot device found
1795  -44   common/cmd_ide.c        Device not available
1796   44   common/cmd_ide.c        Device available
1797  -45   common/cmd_ide.c        wrong partition selected
1798   45   common/cmd_ide.c        partition selected
1799  -46   common/cmd_ide.c        Unknown partition table
1800   46   common/cmd_ide.c        valid partition table found
1801  -47   common/cmd_ide.c        Invalid partition type
1802   47   common/cmd_ide.c        correct partition type
1803  -48   common/cmd_ide.c        Error reading Image Header on boot device
1804   48   common/cmd_ide.c        reading Image Header from IDE device OK
1805  -49   common/cmd_ide.c        Image header has bad magic number
1806   49   common/cmd_ide.c        Image header has correct magic number
1807  -50   common/cmd_ide.c        Image header has bad     checksum
1808   50   common/cmd_ide.c        Image header has correct checksum
1809  -51   common/cmd_ide.c        Error reading Image from IDE device
1810   51   common/cmd_ide.c        reading Image from IDE device OK
1811   52   common/cmd_nand.c       before loading a Image from a NAND device
1812  -53   common/cmd_nand.c       Bad usage of "nand" command
1813   53   common/cmd_nand.c       correct usage of "nand" command
1814  -54   common/cmd_nand.c       No boot device
1815   54   common/cmd_nand.c       boot device found
1816  -55   common/cmd_nand.c       Unknown Chip ID on boot device
1817   55   common/cmd_nand.c       correct chip ID found, device available
1818  -56   common/cmd_nand.c       Error reading Image Header on boot device
1819   56   common/cmd_nand.c       reading Image Header from NAND device OK
1820  -57   common/cmd_nand.c       Image header has bad magic number
1821   57   common/cmd_nand.c       Image header has correct magic number
1822  -58   common/cmd_nand.c       Error reading Image from NAND device
1823   58   common/cmd_nand.c       reading Image from NAND device OK
1824
1825  -60   common/env_common.c     Environment has a bad CRC, using default
1826
1827   64   net/eth.c               starting with Ethernet configuration.
1828  -64   net/eth.c               no Ethernet found.
1829   65   net/eth.c               Ethernet found.
1830
1831  -80   common/cmd_net.c        usage wrong
1832   80   common/cmd_net.c        before calling NetLoop()
1833  -81   common/cmd_net.c        some error in NetLoop() occurred
1834   81   common/cmd_net.c        NetLoop() back without error
1835  -82   common/cmd_net.c        size == 0 (File with size 0 loaded)
1836   82   common/cmd_net.c        trying automatic boot
1837   83   common/cmd_net.c        running autoscript
1838  -83   common/cmd_net.c        some error in automatic boot or autoscript
1839   84   common/cmd_net.c        end without errors
1840
1841FIT uImage format:
1842
1843  Arg   Where                   When
1844  100   common/cmd_bootm.c      Kernel FIT Image has correct format
1845 -100   common/cmd_bootm.c      Kernel FIT Image has incorrect format
1846  101   common/cmd_bootm.c      No Kernel subimage unit name, using configuration
1847 -101   common/cmd_bootm.c      Can't get configuration for kernel subimage
1848  102   common/cmd_bootm.c      Kernel unit name specified
1849 -103   common/cmd_bootm.c      Can't get kernel subimage node offset
1850  103   common/cmd_bootm.c      Found configuration node
1851  104   common/cmd_bootm.c      Got kernel subimage node offset
1852 -104   common/cmd_bootm.c      Kernel subimage hash verification failed
1853  105   common/cmd_bootm.c      Kernel subimage hash verification OK
1854 -105   common/cmd_bootm.c      Kernel subimage is for unsupported architecture
1855  106   common/cmd_bootm.c      Architecture check OK
1856 -106   common/cmd_bootm.c      Kernel subimage has wrong type
1857  107   common/cmd_bootm.c      Kernel subimage type OK
1858 -107   common/cmd_bootm.c      Can't get kernel subimage data/size
1859  108   common/cmd_bootm.c      Got kernel subimage data/size
1860 -108   common/cmd_bootm.c      Wrong image type (not legacy, FIT)
1861 -109   common/cmd_bootm.c      Can't get kernel subimage type
1862 -110   common/cmd_bootm.c      Can't get kernel subimage comp
1863 -111   common/cmd_bootm.c      Can't get kernel subimage os
1864 -112   common/cmd_bootm.c      Can't get kernel subimage load address
1865 -113   common/cmd_bootm.c      Image uncompress/copy overwrite error
1866
1867  120   common/image.c          Start initial ramdisk verification
1868 -120   common/image.c          Ramdisk FIT image has incorrect format
1869  121   common/image.c          Ramdisk FIT image has correct format
1870  122   common/image.c          No ramdisk subimage unit name, using configuration
1871 -122   common/image.c          Can't get configuration for ramdisk subimage
1872  123   common/image.c          Ramdisk unit name specified
1873 -124   common/image.c          Can't get ramdisk subimage node offset
1874  125   common/image.c          Got ramdisk subimage node offset
1875 -125   common/image.c          Ramdisk subimage hash verification failed
1876  126   common/image.c          Ramdisk subimage hash verification OK
1877 -126   common/image.c          Ramdisk subimage for unsupported architecture
1878  127   common/image.c          Architecture check OK
1879 -127   common/image.c          Can't get ramdisk subimage data/size
1880  128   common/image.c          Got ramdisk subimage data/size
1881  129   common/image.c          Can't get ramdisk load address
1882 -129   common/image.c          Got ramdisk load address
1883
1884 -130   common/cmd_doc.c        Incorrect FIT image format
1885  131   common/cmd_doc.c        FIT image format OK
1886
1887 -140   common/cmd_ide.c        Incorrect FIT image format
1888  141   common/cmd_ide.c        FIT image format OK
1889
1890 -150   common/cmd_nand.c       Incorrect FIT image format
1891  151   common/cmd_nand.c       FIT image format OK
1892
1893
1894Modem Support:
1895--------------
1896
1897[so far only for SMDK2400 and TRAB boards]
1898
1899- Modem support enable:
1900                CONFIG_MODEM_SUPPORT
1901
1902- RTS/CTS Flow control enable:
1903                CONFIG_HWFLOW
1904
1905- Modem debug support:
1906                CONFIG_MODEM_SUPPORT_DEBUG
1907
1908                Enables debugging stuff (char screen[1024], dbg())
1909                for modem support. Useful only with BDI2000.
1910
1911- Interrupt support (PPC):
1912
1913                There are common interrupt_init() and timer_interrupt()
1914                for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1915                for CPU specific initialization. interrupt_init_cpu()
1916                should set decrementer_count to appropriate value. If
1917                CPU resets decrementer automatically after interrupt
1918                (ppc4xx) it should set decrementer_count to zero.
1919                timer_interrupt() calls timer_interrupt_cpu() for CPU
1920                specific handling. If board has watchdog / status_led
1921                / other_activity_monitor it works automatically from
1922                general timer_interrupt().
1923
1924- General:
1925
1926                In the target system modem support is enabled when a
1927                specific key (key combination) is pressed during
1928                power-on. Otherwise U-Boot will boot normally
1929                (autoboot). The key_pressed() function is called from
1930                board_init(). Currently key_pressed() is a dummy
1931                function, returning 1 and thus enabling modem
1932                initialization.
1933
1934                If there are no modem init strings in the
1935                environment, U-Boot proceed to autoboot; the
1936                previous output (banner, info printfs) will be
1937                suppressed, though.
1938
1939                See also: doc/README.Modem
1940
1941
1942Configuration Settings:
1943-----------------------
1944
1945- CFG_LONGHELP: Defined when you want long help messages included;
1946                undefine this when you're short of memory.
1947
1948- CFG_PROMPT:   This is what U-Boot prints on the console to
1949                prompt for user input.
1950
1951- CFG_CBSIZE:   Buffer size for input from the Console
1952
1953- CFG_PBSIZE:   Buffer size for Console output
1954
1955- CFG_MAXARGS:  max. Number of arguments accepted for monitor commands
1956
1957- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1958                the application (usually a Linux kernel) when it is
1959                booted
1960
1961- CFG_BAUDRATE_TABLE:
1962                List of legal baudrate settings for this board.
1963
1964- CFG_CONSOLE_INFO_QUIET
1965                Suppress display of console information at boot.
1966
1967- CFG_CONSOLE_IS_IN_ENV
1968                If the board specific function
1969                        extern int overwrite_console (void);
1970                returns 1, the stdin, stderr and stdout are switched to the
1971                serial port, else the settings in the environment are used.
1972
1973- CFG_CONSOLE_OVERWRITE_ROUTINE
1974                Enable the call to overwrite_console().
1975
1976- CFG_CONSOLE_ENV_OVERWRITE
1977                Enable overwrite of previous console environment settings.
1978
1979- CFG_MEMTEST_START, CFG_MEMTEST_END:
1980                Begin and End addresses of the area used by the
1981                simple memory test.
1982
1983- CFG_ALT_MEMTEST:
1984                Enable an alternate, more extensive memory test.
1985
1986- CFG_MEMTEST_SCRATCH:
1987                Scratch address used by the alternate memory test
1988                You only need to set this if address zero isn't writeable
1989
1990- CFG_MEM_TOP_HIDE (PPC only):
1991                If CFG_MEM_TOP_HIDE is defined in the board config header,
1992                this specified memory area will get subtracted from the top
1993                (end) of RAM and won't get "touched" at all by U-Boot. By
1994                fixing up gd->ram_size the Linux kernel should gets passed
1995                the now "corrected" memory size and won't touch it either.
1996                This should work for arch/ppc and arch/powerpc. Only Linux
1997                board ports in arch/powerpc with bootwrapper support that
1998                recalculate the memory size from the SDRAM controller setup
1999                will have to get fixed in Linux additionally.
2000
2001                This option can be used as a workaround for the 440EPx/GRx
2002                CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2003                be touched.
2004
2005                WARNING: Please make sure that this value is a multiple of
2006                the Linux page size (normally 4k). If this is not the case,
2007                then the end address of the Linux memory will be located at a
2008                non page size aligned address and this could cause major
2009                problems.
2010
2011- CFG_TFTP_LOADADDR:
2012                Default load address for network file downloads
2013
2014- CFG_LOADS_BAUD_CHANGE:
2015                Enable temporary baudrate change while serial download
2016
2017- CFG_SDRAM_BASE:
2018                Physical start address of SDRAM. _Must_ be 0 here.
2019
2020- CFG_MBIO_BASE:
2021                Physical start address of Motherboard I/O (if using a
2022                Cogent motherboard)
2023
2024- CFG_FLASH_BASE:
2025                Physical start address of Flash memory.
2026
2027- CFG_MONITOR_BASE:
2028                Physical start address of boot monitor code (set by
2029                make config files to be same as the text base address
2030                (TEXT_BASE) used when linking) - same as
2031                CFG_FLASH_BASE when booting from flash.
2032
2033- CFG_MONITOR_LEN:
2034                Size of memory reserved for monitor code, used to
2035                determine _at_compile_time_ (!) if the environment is
2036                embedded within the U-Boot image, or in a separate
2037                flash sector.
2038
2039- CFG_MALLOC_LEN:
2040                Size of DRAM reserved for malloc() use.
2041
2042- CFG_BOOTM_LEN:
2043                Normally compressed uImages are limited to an
2044                uncompressed size of 8 MBytes. If this is not enough,
2045                you can define CFG_BOOTM_LEN in your board config file
2046                to adjust this setting to your needs.
2047
2048- CFG_BOOTMAPSZ:
2049                Maximum size of memory mapped by the startup code of
2050                the Linux kernel; all data that must be processed by
2051                the Linux kernel (bd_info, boot arguments, FDT blob if
2052                used) must be put below this limit, unless "bootm_low"
2053                enviroment variable is defined and non-zero. In such case
2054                all data for the Linux kernel must be between "bootm_low"
2055                and "bootm_low" + CFG_BOOTMAPSZ.
2056
2057- CFG_MAX_FLASH_BANKS:
2058                Max number of Flash memory banks
2059
2060- CFG_MAX_FLASH_SECT:
2061                Max number of sectors on a Flash chip
2062
2063- CFG_FLASH_ERASE_TOUT:
2064                Timeout for Flash erase operations (in ms)
2065
2066- CFG_FLASH_WRITE_TOUT:
2067                Timeout for Flash write operations (in ms)
2068
2069- CFG_FLASH_LOCK_TOUT
2070                Timeout for Flash set sector lock bit operation (in ms)
2071
2072- CFG_FLASH_UNLOCK_TOUT
2073                Timeout for Flash clear lock bits operation (in ms)
2074
2075- CFG_FLASH_PROTECTION
2076                If defined, hardware flash sectors protection is used
2077                instead of U-Boot software protection.
2078
2079- CFG_DIRECT_FLASH_TFTP:
2080
2081                Enable TFTP transfers directly to flash memory;
2082                without this option such a download has to be
2083                performed in two steps: (1) download to RAM, and (2)
2084                copy from RAM to flash.
2085
2086                The two-step approach is usually more reliable, since
2087                you can check if the download worked before you erase
2088                the flash, but in some situations (when system RAM is
2089                too limited to allow for a temporary copy of the
2090                downloaded image) this option may be very useful.
2091
2092- CFG_FLASH_CFI:
2093                Define if the flash driver uses extra elements in the
2094                common flash structure for storing flash geometry.
2095
2096- CONFIG_FLASH_CFI_DRIVER
2097                This option also enables the building of the cfi_flash driver
2098                in the drivers directory
2099
2100- CFG_FLASH_USE_BUFFER_WRITE
2101                Use buffered writes to flash.
2102
2103- CONFIG_FLASH_SPANSION_S29WS_N
2104                s29ws-n MirrorBit flash has non-standard addresses for buffered
2105                write commands.
2106
2107- CFG_FLASH_QUIET_TEST
2108                If this option is defined, the common CFI flash doesn't
2109                print it's warning upon not recognized FLASH banks. This
2110                is useful, if some of the configured banks are only
2111                optionally available.
2112
2113- CONFIG_FLASH_SHOW_PROGRESS
2114                If defined (must be an integer), print out countdown
2115                digits and dots.  Recommended value: 45 (9..1) for 80
2116                column displays, 15 (3..1) for 40 column displays.
2117
2118- CFG_RX_ETH_BUFFER:
2119                Defines the number of Ethernet receive buffers. On some
2120                Ethernet controllers it is recommended to set this value
2121                to 8 or even higher (EEPRO100 or 405 EMAC), since all
2122                buffers can be full shortly after enabling the interface
2123                on high Ethernet traffic.
2124                Defaults to 4 if not defined.
2125
2126The following definitions that deal with the placement and management
2127of environment data (variable area); in general, we support the
2128following configurations:
2129
2130- CONFIG_ENV_IS_IN_FLASH:
2131
2132        Define this if the environment is in flash memory.
2133
2134        a) The environment occupies one whole flash sector, which is
2135           "embedded" in the text segment with the U-Boot code. This
2136           happens usually with "bottom boot sector" or "top boot
2137           sector" type flash chips, which have several smaller
2138           sectors at the start or the end. For instance, such a
2139           layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2140           such a case you would place the environment in one of the
2141           4 kB sectors - with U-Boot code before and after it. With
2142           "top boot sector" type flash chips, you would put the
2143           environment in one of the last sectors, leaving a gap
2144           between U-Boot and the environment.
2145
2146        - CONFIG_ENV_OFFSET:
2147
2148           Offset of environment data (variable area) to the
2149           beginning of flash memory; for instance, with bottom boot
2150           type flash chips the second sector can be used: the offset
2151           for this sector is given here.
2152
2153           CONFIG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
2154
2155        - CONFIG_ENV_ADDR:
2156
2157           This is just another way to specify the start address of
2158           the flash sector containing the environment (instead of
2159           CONFIG_ENV_OFFSET).
2160
2161        - CONFIG_ENV_SECT_SIZE:
2162
2163           Size of the sector containing the environment.
2164
2165
2166        b) Sometimes flash chips have few, equal sized, BIG sectors.
2167           In such a case you don't want to spend a whole sector for
2168           the environment.
2169
2170        - CONFIG_ENV_SIZE:
2171
2172           If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2173           and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2174           of this flash sector for the environment. This saves
2175           memory for the RAM copy of the environment.
2176
2177           It may also save flash memory if you decide to use this
2178           when your environment is "embedded" within U-Boot code,
2179           since then the remainder of the flash sector could be used
2180           for U-Boot code. It should be pointed out that this is
2181           STRONGLY DISCOURAGED from a robustness point of view:
2182           updating the environment in flash makes it always
2183           necessary to erase the WHOLE sector. If something goes
2184           wrong before the contents has been restored from a copy in
2185           RAM, your target system will be dead.
2186
2187        - CONFIG_ENV_ADDR_REDUND
2188          CONFIG_ENV_SIZE_REDUND
2189
2190           These settings describe a second storage area used to hold
2191           a redundant copy of the environment data, so that there is
2192           a valid backup copy in case there is a power failure during
2193           a "saveenv" operation.
2194
2195BE CAREFUL! Any changes to the flash layout, and some changes to the
2196source code will make it necessary to adapt <board>/u-boot.lds*
2197accordingly!
2198
2199
2200- CONFIG_ENV_IS_IN_NVRAM:
2201
2202        Define this if you have some non-volatile memory device
2203        (NVRAM, battery buffered SRAM) which you want to use for the
2204        environment.
2205
2206        - CONFIG_ENV_ADDR:
2207        - CONFIG_ENV_SIZE:
2208
2209          These two #defines are used to determine the memory area you
2210          want to use for environment. It is assumed that this memory
2211          can just be read and written to, without any special
2212          provision.
2213
2214BE CAREFUL! The first access to the environment happens quite early
2215in U-Boot initalization (when we try to get the setting of for the
2216console baudrate). You *MUST* have mapped your NVRAM area then, or
2217U-Boot will hang.
2218
2219Please note that even with NVRAM we still use a copy of the
2220environment in RAM: we could work on NVRAM directly, but we want to
2221keep settings there always unmodified except somebody uses "saveenv"
2222to save the current settings.
2223
2224
2225- CONFIG_ENV_IS_IN_EEPROM:
2226
2227        Use this if you have an EEPROM or similar serial access
2228        device and a driver for it.
2229
2230        - CONFIG_ENV_OFFSET:
2231        - CONFIG_ENV_SIZE:
2232
2233          These two #defines specify the offset and size of the
2234          environment area within the total memory of your EEPROM.
2235
2236        - CFG_I2C_EEPROM_ADDR:
2237          If defined, specified the chip address of the EEPROM device.
2238          The default address is zero.
2239
2240        - CFG_EEPROM_PAGE_WRITE_BITS:
2241          If defined, the number of bits used to address bytes in a
2242          single page in the EEPROM device.  A 64 byte page, for example
2243          would require six bits.
2244
2245        - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2246          If defined, the number of milliseconds to delay between
2247          page writes.  The default is zero milliseconds.
2248
2249        - CFG_I2C_EEPROM_ADDR_LEN:
2250          The length in bytes of the EEPROM memory array address.  Note
2251          that this is NOT the chip address length!
2252
2253        - CFG_I2C_EEPROM_ADDR_OVERFLOW:
2254          EEPROM chips that implement "address overflow" are ones
2255          like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2256          address and the extra bits end up in the "chip address" bit
2257          slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2258          byte chips.
2259
2260          Note that we consider the length of the address field to
2261          still be one byte because the extra address bits are hidden
2262          in the chip address.
2263
2264        - CFG_EEPROM_SIZE:
2265          The size in bytes of the EEPROM device.
2266
2267
2268- CONFIG_ENV_IS_IN_DATAFLASH:
2269
2270        Define this if you have a DataFlash memory device which you
2271        want to use for the environment.
2272
2273        - CONFIG_ENV_OFFSET:
2274        - CONFIG_ENV_ADDR:
2275        - CONFIG_ENV_SIZE:
2276
2277          These three #defines specify the offset and size of the
2278          environment area within the total memory of your DataFlash placed
2279          at the specified address.
2280
2281- CONFIG_ENV_IS_IN_NAND:
2282
2283        Define this if you have a NAND device which you want to use
2284        for the environment.
2285
2286        - CONFIG_ENV_OFFSET:
2287        - CONFIG_ENV_SIZE:
2288
2289          These two #defines specify the offset and size of the environment
2290          area within the first NAND device.
2291
2292        - CONFIG_ENV_OFFSET_REDUND
2293
2294          This setting describes a second storage area of CONFIG_ENV_SIZE
2295          size used to hold a redundant copy of the environment data,
2296          so that there is a valid backup copy in case there is a
2297          power failure during a "saveenv" operation.
2298
2299        Note: CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND must be aligned
2300        to a block boundary, and CONFIG_ENV_SIZE must be a multiple of
2301        the NAND devices block size.
2302
2303- CFG_SPI_INIT_OFFSET
2304
2305        Defines offset to the initial SPI buffer area in DPRAM. The
2306        area is used at an early stage (ROM part) if the environment
2307        is configured to reside in the SPI EEPROM: We need a 520 byte
2308        scratch DPRAM area. It is used between the two initialization
2309        calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2310        to be a good choice since it makes it far enough from the
2311        start of the data area as well as from the stack pointer.
2312
2313Please note that the environment is read-only until the monitor
2314has been relocated to RAM and a RAM copy of the environment has been
2315created; also, when using EEPROM you will have to use getenv_r()
2316until then to read environment variables.
2317
2318The environment is protected by a CRC32 checksum. Before the monitor
2319is relocated into RAM, as a result of a bad CRC you will be working
2320with the compiled-in default environment - *silently*!!! [This is
2321necessary, because the first environment variable we need is the
2322"baudrate" setting for the console - if we have a bad CRC, we don't
2323have any device yet where we could complain.]
2324
2325Note: once the monitor has been relocated, then it will complain if
2326the default environment is used; a new CRC is computed as soon as you
2327use the "saveenv" command to store a valid environment.
2328
2329- CFG_FAULT_ECHO_LINK_DOWN:
2330                Echo the inverted Ethernet link state to the fault LED.
2331
2332                Note: If this option is active, then CFG_FAULT_MII_ADDR
2333                      also needs to be defined.
2334
2335- CFG_FAULT_MII_ADDR:
2336                MII address of the PHY to check for the Ethernet link state.
2337
2338- CFG_64BIT_VSPRINTF:
2339                Makes vsprintf (and all *printf functions) support printing
2340                of 64bit values by using the L quantifier
2341
2342- CFG_64BIT_STRTOUL:
2343                Adds simple_strtoull that returns a 64bit value
2344
2345Low Level (hardware related) configuration options:
2346---------------------------------------------------
2347
2348- CFG_CACHELINE_SIZE:
2349                Cache Line Size of the CPU.
2350
2351- CFG_DEFAULT_IMMR:
2352                Default address of the IMMR after system reset.
2353
2354                Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2355                and RPXsuper) to be able to adjust the position of
2356                the IMMR register after a reset.
2357
2358- Floppy Disk Support:
2359                CFG_FDC_DRIVE_NUMBER
2360
2361                the default drive number (default value 0)
2362
2363                CFG_ISA_IO_STRIDE
2364
2365                defines the spacing between FDC chipset registers
2366                (default value 1)
2367
2368                CFG_ISA_IO_OFFSET
2369
2370                defines the offset of register from address. It
2371                depends on which part of the data bus is connected to
2372                the FDC chipset. (default value 0)
2373
2374                If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2375                CFG_FDC_DRIVE_NUMBER are undefined, they take their
2376                default value.
2377
2378                if CFG_FDC_HW_INIT is defined, then the function
2379                fdc_hw_init() is called at the beginning of the FDC
2380                setup. fdc_hw_init() must be provided by the board
2381                source code. It is used to make hardware dependant
2382                initializations.
2383
2384- CFG_IMMR:     Physical address of the Internal Memory.
2385                DO NOT CHANGE unless you know exactly what you're
2386                doing! (11-4) [MPC8xx/82xx systems only]
2387
2388- CFG_INIT_RAM_ADDR:
2389
2390                Start address of memory area that can be used for
2391                initial data and stack; please note that this must be
2392                writable memory that is working WITHOUT special
2393                initialization, i. e. you CANNOT use normal RAM which
2394                will become available only after programming the
2395                memory controller and running certain initialization
2396                sequences.
2397
2398                U-Boot uses the following memory types:
2399                - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2400                - MPC824X: data cache
2401                - PPC4xx:  data cache
2402
2403- CFG_GBL_DATA_OFFSET:
2404
2405                Offset of the initial data structure in the memory
2406                area defined by CFG_INIT_RAM_ADDR. Usually
2407                CFG_GBL_DATA_OFFSET is chosen such that the initial
2408                data is located at the end of the available space
2409                (sometimes written as (CFG_INIT_RAM_END -
2410                CFG_INIT_DATA_SIZE), and the initial stack is just
2411                below that area (growing from (CFG_INIT_RAM_ADDR +
2412                CFG_GBL_DATA_OFFSET) downward.
2413
2414        Note:
2415                On the MPC824X (or other systems that use the data
2416                cache for initial memory) the address chosen for
2417                CFG_INIT_RAM_ADDR is basically arbitrary - it must
2418                point to an otherwise UNUSED address space between
2419                the top of RAM and the start of the PCI space.
2420
2421- CFG_SIUMCR:   SIU Module Configuration (11-6)
2422
2423- CFG_SYPCR:    System Protection Control (11-9)
2424
2425- CFG_TBSCR:    Time Base Status and Control (11-26)
2426
2427- CFG_PISCR:    Periodic Interrupt Status and Control (11-31)
2428
2429- CFG_PLPRCR:   PLL, Low-Power, and Reset Control Register (15-30)
2430
2431- CFG_SCCR:     System Clock and reset Control Register (15-27)
2432
2433- CFG_OR_TIMING_SDRAM:
2434                SDRAM timing
2435
2436- CFG_MAMR_PTA:
2437                periodic timer for refresh
2438
2439- CFG_DER:      Debug Event Register (37-47)
2440
2441- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2442  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2443  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2444  CFG_BR1_PRELIM:
2445                Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2446
2447- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2448  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2449  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2450                Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2451
2452- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2453  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2454                Machine Mode Register and Memory Periodic Timer
2455                Prescaler definitions (SDRAM timing)
2456
2457- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2458                enable I2C microcode relocation patch (MPC8xx);
2459                define relocation offset in DPRAM [DSP2]
2460
2461- CFG_SMC_UCODE_PATCH, CFG_SMC_DPMEM_OFFSET [0x1FC0]:
2462                enable SMC microcode relocation patch (MPC8xx);
2463                define relocation offset in DPRAM [SMC1]
2464
2465- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2466                enable SPI microcode relocation patch (MPC8xx);
2467                define relocation offset in DPRAM [SCC4]
2468
2469- CFG_USE_OSCCLK:
2470                Use OSCM clock mode on MBX8xx board. Be careful,
2471                wrong setting might damage your board. Read
2472                doc/README.MBX before setting this variable!
2473
2474- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2475                Offset of the bootmode word in DPRAM used by post
2476                (Power On Self Tests). This definition overrides
2477                #define'd default value in commproc.h resp.
2478                cpm_8260.h.
2479
2480- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2481  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2482  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2483  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2484  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2485  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2486  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2487  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2488                Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2489
2490- CONFIG_SPD_EEPROM
2491                Get DDR timing information from an I2C EEPROM. Common
2492                with pluggable memory modules such as SODIMMs
2493
2494  SPD_EEPROM_ADDRESS
2495                I2C address of the SPD EEPROM
2496
2497- CFG_SPD_BUS_NUM
2498                If SPD EEPROM is on an I2C bus other than the first
2499                one, specify here. Note that the value must resolve
2500                to something your driver can deal with.
2501
2502- CFG_83XX_DDR_USES_CS0
2503                Only for 83xx systems. If specified, then DDR should
2504                be configured using CS0 and CS1 instead of CS2 and CS3.
2505
2506- CFG_83XX_DDR_USES_CS0
2507                Only for 83xx systems. If specified, then DDR should
2508                be configured using CS0 and CS1 instead of CS2 and CS3.
2509
2510- CONFIG_ETHER_ON_FEC[12]
2511                Define to enable FEC[12] on a 8xx series processor.
2512
2513- CONFIG_FEC[12]_PHY
2514                Define to the hardcoded PHY address which corresponds
2515                to the given FEC; i. e.
2516                        #define CONFIG_FEC1_PHY 4
2517                means that the PHY with address 4 is connected to FEC1
2518
2519                When set to -1, means to probe for first available.
2520
2521- CONFIG_FEC[12]_PHY_NORXERR
2522                The PHY does not have a RXERR line (RMII only).
2523                (so program the FEC to ignore it).
2524
2525- CONFIG_RMII
2526                Enable RMII mode for all FECs.
2527                Note that this is a global option, we can't
2528                have one FEC in standard MII mode and another in RMII mode.
2529
2530- CONFIG_CRC32_VERIFY
2531                Add a verify option to the crc32 command.
2532                The syntax is:
2533
2534                => crc32 -v <address> <count> <crc32>
2535
2536                Where address/count indicate a memory area
2537                and crc32 is the correct crc32 which the
2538                area should have.
2539
2540- CONFIG_LOOPW
2541                Add the "loopw" memory command. This only takes effect if
2542                the memory commands are activated globally (CONFIG_CMD_MEM).
2543
2544- CONFIG_MX_CYCLIC
2545                Add the "mdc" and "mwc" memory commands. These are cyclic
2546                "md/mw" commands.
2547                Examples:
2548
2549                => mdc.b 10 4 500
2550                This command will print 4 bytes (10,11,12,13) each 500 ms.
2551
2552                => mwc.l 100 12345678 10
2553                This command will write 12345678 to address 100 all 10 ms.
2554
2555                This only takes effect if the memory commands are activated
2556                globally (CONFIG_CMD_MEM).
2557
2558- CONFIG_SKIP_LOWLEVEL_INIT
2559- CONFIG_SKIP_RELOCATE_UBOOT
2560
2561                [ARM only] If these variables are defined, then
2562                certain low level initializations (like setting up
2563                the memory controller) are omitted and/or U-Boot does
2564                not relocate itself into RAM.
2565                Normally these variables MUST NOT be defined. The
2566                only exception is when U-Boot is loaded (to RAM) by
2567                some other boot loader or by a debugger which
2568                performs these initializations itself.
2569
2570
2571Building the Software:
2572======================
2573
2574Building U-Boot has been tested in several native build environments
2575and in many different cross environments. Of course we cannot support
2576all possibly existing versions of cross development tools in all
2577(potentially obsolete) versions. In case of tool chain problems we
2578recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2579which is extensively used to build and test U-Boot.
2580
2581If you are not using a native environment, it is assumed that you
2582have GNU cross compiling tools available in your path. In this case,
2583you must set the environment variable CROSS_COMPILE in your shell.
2584Note that no changes to the Makefile or any other source files are
2585necessary. For example using the ELDK on a 4xx CPU, please enter:
2586
2587        $ CROSS_COMPILE=ppc_4xx-
2588        $ export CROSS_COMPILE
2589
2590U-Boot is intended to be simple to build. After installing the
2591sources you must configure U-Boot for one specific board type. This
2592is done by typing:
2593
2594        make NAME_config
2595
2596where "NAME_config" is the name of one of the existing configu-
2597rations; see the main Makefile for supported names.
2598
2599Note: for some board special configuration names may exist; check if
2600      additional information is available from the board vendor; for
2601      instance, the TQM823L systems are available without (standard)
2602      or with LCD support. You can select such additional "features"
2603      when choosing the configuration, i. e.
2604
2605      make TQM823L_config
2606        - will configure for a plain TQM823L, i. e. no LCD support
2607
2608      make TQM823L_LCD_config
2609        - will configure for a TQM823L with U-Boot console on LCD
2610
2611      etc.
2612
2613
2614Finally, type "make all", and you should get some working U-Boot
2615images ready for download to / installation on your system:
2616
2617- "u-boot.bin" is a raw binary image
2618- "u-boot" is an image in ELF binary format
2619- "u-boot.srec" is in Motorola S-Record format
2620
2621By default the build is performed locally and the objects are saved
2622in the source directory. One of the two methods can be used to change
2623this behavior and build U-Boot to some external directory:
2624
26251. Add O= to the make command line invocations:
2626
2627        make O=/tmp/build distclean
2628        make O=/tmp/build NAME_config
2629        make O=/tmp/build all
2630
26312. Set environment variable BUILD_DIR to point to the desired location:
2632
2633        export BUILD_DIR=/tmp/build
2634        make distclean
2635        make NAME_config
2636        make all
2637
2638Note that the command line "O=" setting overrides the BUILD_DIR environment
2639variable.
2640
2641
2642Please be aware that the Makefiles assume you are using GNU make, so
2643for instance on NetBSD you might need to use "gmake" instead of
2644native "make".
2645
2646
2647If the system board that you have is not listed, then you will need
2648to port U-Boot to your hardware platform. To do this, follow these
2649steps:
2650
26511.  Add a new configuration option for your board to the toplevel
2652    "Makefile" and to the "MAKEALL" script, using the existing
2653    entries as examples. Note that here and at many other places
2654    boards and other names are listed in alphabetical sort order. Please
2655    keep this order.
26562.  Create a new directory to hold your board specific code. Add any
2657    files you need. In your board directory, you will need at least
2658    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
26593.  Create a new configuration file "include/configs/<board>.h" for
2660    your board
26613.  If you're porting U-Boot to a new CPU, then also create a new
2662    directory to hold your CPU specific code. Add any files you need.
26634.  Run "make <board>_config" with your new name.
26645.  Type "make", and you should get a working "u-boot.srec" file
2665    to be installed on your target system.
26666.  Debug and solve any problems that might arise.
2667    [Of course, this last step is much harder than it sounds.]
2668
2669
2670Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2671==============================================================
2672
2673If you have modified U-Boot sources (for instance added a new board
2674or support for new devices, a new CPU, etc.) you are expected to
2675provide feedback to the other developers. The feedback normally takes
2676the form of a "patch", i. e. a context diff against a certain (latest
2677official or latest in the git repository) version of U-Boot sources.
2678
2679But before you submit such a patch, please verify that your modifi-
2680cation did not break existing code. At least make sure that *ALL* of
2681the supported boards compile WITHOUT ANY compiler warnings. To do so,
2682just run the "MAKEALL" script, which will configure and build U-Boot
2683for ALL supported system. Be warned, this will take a while. You can
2684select which (cross) compiler to use by passing a `CROSS_COMPILE'
2685environment variable to the script, i. e. to use the ELDK cross tools
2686you can type
2687
2688        CROSS_COMPILE=ppc_8xx- MAKEALL
2689
2690or to build on a native PowerPC system you can type
2691
2692        CROSS_COMPILE=' ' MAKEALL
2693
2694When using the MAKEALL script, the default behaviour is to build
2695U-Boot in the source directory. This location can be changed by
2696setting the BUILD_DIR environment variable. Also, for each target
2697built, the MAKEALL script saves two log files (<target>.ERR and
2698<target>.MAKEALL) in the <source dir>/LOG directory. This default
2699location can be changed by setting the MAKEALL_LOGDIR environment
2700variable. For example:
2701
2702        export BUILD_DIR=/tmp/build
2703        export MAKEALL_LOGDIR=/tmp/log
2704        CROSS_COMPILE=ppc_8xx- MAKEALL
2705
2706With the above settings build objects are saved in the /tmp/build,
2707log files are saved in the /tmp/log and the source tree remains clean
2708during the whole build process.
2709
2710
2711See also "U-Boot Porting Guide" below.
2712
2713
2714Monitor Commands - Overview:
2715============================
2716
2717go      - start application at address 'addr'
2718run     - run commands in an environment variable
2719bootm   - boot application image from memory
2720bootp   - boot image via network using BootP/TFTP protocol
2721tftpboot- boot image via network using TFTP protocol
2722               and env variables "ipaddr" and "serverip"
2723               (and eventually "gatewayip")
2724rarpboot- boot image via network using RARP/TFTP protocol
2725diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2726loads   - load S-Record file over serial line
2727loadb   - load binary file over serial line (kermit mode)
2728md      - memory display
2729mm      - memory modify (auto-incrementing)
2730nm      - memory modify (constant address)
2731mw      - memory write (fill)
2732cp      - memory copy
2733cmp     - memory compare
2734crc32   - checksum calculation
2735imd     - i2c memory display
2736imm     - i2c memory modify (auto-incrementing)
2737inm     - i2c memory modify (constant address)
2738imw     - i2c memory write (fill)
2739icrc32  - i2c checksum calculation
2740iprobe  - probe to discover valid I2C chip addresses
2741iloop   - infinite loop on address range
2742isdram  - print SDRAM configuration information
2743sspi    - SPI utility commands
2744base    - print or set address offset
2745printenv- print environment variables
2746setenv  - set environment variables
2747saveenv - save environment variables to persistent storage
2748protect - enable or disable FLASH write protection
2749erase   - erase FLASH memory
2750flinfo  - print FLASH memory information
2751bdinfo  - print Board Info structure
2752iminfo  - print header information for application image
2753coninfo - print console devices and informations
2754ide     - IDE sub-system
2755loop    - infinite loop on address range
2756loopw   - infinite write loop on address range
2757mtest   - simple RAM test
2758icache  - enable or disable instruction cache
2759dcache  - enable or disable data cache
2760reset   - Perform RESET of the CPU
2761echo    - echo args to console
2762version - print monitor version
2763help    - print online help
2764?       - alias for 'help'
2765
2766
2767Monitor Commands - Detailed Description:
2768========================================
2769
2770TODO.
2771
2772For now: just type "help <command>".
2773
2774
2775Environment Variables:
2776======================
2777
2778U-Boot supports user configuration using Environment Variables which
2779can be made persistent by saving to Flash memory.
2780
2781Environment Variables are set using "setenv", printed using
2782"printenv", and saved to Flash using "saveenv". Using "setenv"
2783without a value can be used to delete a variable from the
2784environment. As long as you don't save the environment you are
2785working with an in-memory copy. In case the Flash area containing the
2786environment is erased by accident, a default environment is provided.
2787
2788Some configuration options can be set using Environment Variables:
2789
2790  baudrate      - see CONFIG_BAUDRATE
2791
2792  bootdelay     - see CONFIG_BOOTDELAY
2793
2794  bootcmd       - see CONFIG_BOOTCOMMAND
2795
2796  bootargs      - Boot arguments when booting an RTOS image
2797
2798  bootfile      - Name of the image to load with TFTP
2799
2800  bootm_low     - Memory range available for image processing in the bootm
2801                  command can be restricted. This variable is given as
2802                  a hexadecimal number and defines lowest address allowed
2803                  for use by the bootm command. See also "bootm_size"
2804                  environment variable. Address defined by "bootm_low" is
2805                  also the base of the initial memory mapping for the Linux
2806                  kernel -- see the description of CFG_BOOTMAPSZ.
2807
2808  bootm_size    - Memory range available for image processing in the bootm
2809                  command can be restricted. This variable is given as
2810                  a hexadecimal number and defines the size of the region
2811                  allowed for use by the bootm command. See also "bootm_low"
2812                  environment variable.
2813
2814  autoload      - if set to "no" (any string beginning with 'n'),
2815                  "bootp" will just load perform a lookup of the
2816                  configuration from the BOOTP server, but not try to
2817                  load any image using TFTP
2818
2819  autoscript    - if set to "yes" commands like "loadb", "loady",
2820                  "bootp", "tftpb", "rarpboot" and "nfs" will attempt
2821                  to automatically run script images (by internally
2822                  calling "autoscript").
2823
2824  autoscript_uname - if script image is in a format (FIT) this
2825                     variable is used to get script subimage unit name.
2826
2827  autostart     - if set to "yes", an image loaded using the "bootp",
2828                  "rarpboot", "tftpboot" or "diskboot" commands will
2829                  be automatically started (by internally calling
2830                  "bootm")
2831
2832                  If set to "no", a standalone image passed to the
2833                  "bootm" command will be copied to the load address
2834                  (and eventually uncompressed), but NOT be started.
2835                  This can be used to load and uncompress arbitrary
2836                  data.
2837
2838  i2cfast       - (PPC405GP|PPC405EP only)
2839                  if set to 'y' configures Linux I2C driver for fast
2840                  mode (400kHZ). This environment variable is used in
2841                  initialization code. So, for changes to be effective
2842                  it must be saved and board must be reset.
2843
2844  initrd_high   - restrict positioning of initrd images:
2845                  If this variable is not set, initrd images will be
2846                  copied to the highest possible address in RAM; this
2847                  is usually what you want since it allows for
2848                  maximum initrd size. If for some reason you want to
2849                  make sure that the initrd image is loaded below the
2850                  CFG_BOOTMAPSZ limit, you can set this environment
2851                  variable to a value of "no" or "off" or "0".
2852                  Alternatively, you can set it to a maximum upper
2853                  address to use (U-Boot will still check that it
2854                  does not overwrite the U-Boot stack and data).
2855
2856                  For instance, when you have a system with 16 MB
2857                  RAM, and want to reserve 4 MB from use by Linux,
2858                  you can do this by adding "mem=12M" to the value of
2859                  the "bootargs" variable. However, now you must make
2860                  sure that the initrd image is placed in the first
2861                  12 MB as well - this can be done with
2862
2863                  setenv initrd_high 00c00000
2864
2865                  If you set initrd_high to 0xFFFFFFFF, this is an
2866                  indication to U-Boot that all addresses are legal
2867                  for the Linux kernel, including addresses in flash
2868                  memory. In this case U-Boot will NOT COPY the
2869                  ramdisk at all. This may be useful to reduce the
2870                  boot time on your system, but requires that this
2871                  feature is supported by your Linux kernel.
2872
2873  ipaddr        - IP address; needed for tftpboot command
2874
2875  loadaddr      - Default load address for commands like "bootp",
2876                  "rarpboot", "tftpboot", "loadb" or "diskboot"
2877
2878  loads_echo    - see CONFIG_LOADS_ECHO
2879
2880  serverip      - TFTP server IP address; needed for tftpboot command
2881
2882  bootretry     - see CONFIG_BOOT_RETRY_TIME
2883
2884  bootdelaykey  - see CONFIG_AUTOBOOT_DELAY_STR
2885
2886  bootstopkey   - see CONFIG_AUTOBOOT_STOP_STR
2887
2888  ethprime      - When CONFIG_NET_MULTI is enabled controls which
2889                  interface is used first.
2890
2891  ethact        - When CONFIG_NET_MULTI is enabled controls which
2892                  interface is currently active. For example you
2893                  can do the following
2894
2895                  => setenv ethact FEC ETHERNET
2896                  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2897                  => setenv ethact SCC ETHERNET
2898                  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2899
2900  ethrotate     - When set to "no" U-Boot does not go through all
2901                  available network interfaces.
2902                  It just stays at the currently selected interface.
2903
2904   netretry     - When set to "no" each network operation will
2905                  either succeed or fail without retrying.
2906                  When set to "once" the network operation will
2907                  fail when all the available network interfaces
2908                  are tried once without success.
2909                  Useful on scripts which control the retry operation
2910                  themselves.
2911
2912  npe_ucode     - see CONFIG_IXP4XX_NPE_EXT_UCOD
2913                  if set load address for the NPE microcode
2914
2915  tftpsrcport   - If this is set, the value is used for TFTP's
2916                  UDP source port.
2917
2918  tftpdstport   - If this is set, the value is used for TFTP's UDP
2919                  destination port instead of the Well Know Port 69.
2920
2921   vlan         - When set to a value < 4095 the traffic over
2922                  Ethernet is encapsulated/received over 802.1q
2923                  VLAN tagged frames.
2924
2925The following environment variables may be used and automatically
2926updated by the network boot commands ("bootp" and "rarpboot"),
2927depending the information provided by your boot server:
2928
2929  bootfile      - see above
2930  dnsip         - IP address of your Domain Name Server
2931  dnsip2        - IP address of your secondary Domain Name Server
2932  gatewayip     - IP address of the Gateway (Router) to use
2933  hostname      - Target hostname
2934  ipaddr        - see above
2935  netmask       - Subnet Mask
2936  rootpath      - Pathname of the root filesystem on the NFS server
2937  serverip      - see above
2938
2939
2940There are two special Environment Variables:
2941
2942  serial#       - contains hardware identification information such
2943                  as type string and/or serial number
2944  ethaddr       - Ethernet address
2945
2946These variables can be set only once (usually during manufacturing of
2947the board). U-Boot refuses to delete or overwrite these variables
2948once they have been set once.
2949
2950
2951Further special Environment Variables:
2952
2953  ver           - Contains the U-Boot version string as printed
2954                  with the "version" command. This variable is
2955                  readonly (see CONFIG_VERSION_VARIABLE).
2956
2957
2958Please note that changes to some configuration parameters may take
2959only effect after the next boot (yes, that's just like Windoze :-).
2960
2961
2962Command Line Parsing:
2963=====================
2964
2965There are two different command line parsers available with U-Boot:
2966the old "simple" one, and the much more powerful "hush" shell:
2967
2968Old, simple command line parser:
2969--------------------------------
2970
2971- supports environment variables (through setenv / saveenv commands)
2972- several commands on one line, separated by ';'
2973- variable substitution using "... ${name} ..." syntax
2974- special characters ('$', ';') can be escaped by prefixing with '\',
2975  for example:
2976        setenv bootcmd bootm \${address}
2977- You can also escape text by enclosing in single apostrophes, for example:
2978        setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2979
2980Hush shell:
2981-----------
2982
2983- similar to Bourne shell, with control structures like
2984  if...then...else...fi, for...do...done; while...do...done,
2985  until...do...done, ...
2986- supports environment ("global") variables (through setenv / saveenv
2987  commands) and local shell variables (through standard shell syntax
2988  "name=value"); only environment variables can be used with "run"
2989  command
2990
2991General rules:
2992--------------
2993
2994(1) If a command line (or an environment variable executed by a "run"
2995    command) contains several commands separated by semicolon, and
2996    one of these commands fails, then the remaining commands will be
2997    executed anyway.
2998
2999(2) If you execute several variables with one call to run (i. e.
3000    calling run with a list of variables as arguments), any failing
3001    command will cause "run" to terminate, i. e. the remaining
3002    variables are not executed.
3003
3004Note for Redundant Ethernet Interfaces:
3005=======================================
3006
3007Some boards come with redundant Ethernet interfaces; U-Boot supports
3008such configurations and is capable of automatic selection of a
3009"working" interface when needed. MAC assignment works as follows:
3010
3011Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3012MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3013"eth1addr" (=>eth1), "eth2addr", ...
3014
3015If the network interface stores some valid MAC address (for instance
3016in SROM), this is used as default address if there is NO correspon-
3017ding setting in the environment; if the corresponding environment
3018variable is set, this overrides the settings in the card; that means:
3019
3020o If the SROM has a valid MAC address, and there is no address in the
3021  environment, the SROM's address is used.
3022
3023o If there is no valid address in the SROM, and a definition in the
3024  environment exists, then the value from the environment variable is
3025  used.
3026
3027o If both the SROM and the environment contain a MAC address, and
3028  both addresses are the same, this MAC address is used.
3029
3030o If both the SROM and the environment contain a MAC address, and the
3031  addresses differ, the value from the environment is used and a
3032  warning is printed.
3033
3034o If neither SROM nor the environment contain a MAC address, an error
3035  is raised.
3036
3037
3038Image Formats:
3039==============
3040
3041U-Boot is capable of booting (and performing other auxiliary operations on)
3042images in two formats:
3043
3044New uImage format (FIT)
3045-----------------------
3046
3047Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3048to Flattened Device Tree). It allows the use of images with multiple
3049components (several kernels, ramdisks, etc.), with contents protected by
3050SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3051
3052
3053Old uImage format
3054-----------------
3055
3056Old image format is based on binary files which can be basically anything,
3057preceded by a special header; see the definitions in include/image.h for
3058details; basically, the header defines the following image properties:
3059
3060* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3061  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3062  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3063  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3064  INTEGRITY).
3065* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3066  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3067  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3068* Compression Type (uncompressed, gzip, bzip2)
3069* Load Address
3070* Entry Point
3071* Image Name
3072* Image Timestamp
3073
3074The header is marked by a special Magic Number, and both the header
3075and the data portions of the image are secured against corruption by
3076CRC32 checksums.
3077
3078
3079Linux Support:
3080==============
3081
3082Although U-Boot should support any OS or standalone application
3083easily, the main focus has always been on Linux during the design of
3084U-Boot.
3085
3086U-Boot includes many features that so far have been part of some
3087special "boot loader" code within the Linux kernel. Also, any
3088"initrd" images to be used are no longer part of one big Linux image;
3089instead, kernel and "initrd" are separate images. This implementation
3090serves several purposes:
3091
3092- the same features can be used for other OS or standalone
3093  applications (for instance: using compressed images to reduce the
3094  Flash memory footprint)
3095
3096- it becomes much easier to port new Linux kernel versions because
3097  lots of low-level, hardware dependent stuff are done by U-Boot
3098
3099- the same Linux kernel image can now be used with different "initrd"
3100  images; of course this also means that different kernel images can
3101  be run with the same "initrd". This makes testing easier (you don't
3102  have to build a new "zImage.initrd" Linux image when you just
3103  change a file in your "initrd"). Also, a field-upgrade of the
3104  software is easier now.
3105
3106
3107Linux HOWTO:
3108============
3109
3110Porting Linux to U-Boot based systems:
3111---------------------------------------
3112
3113U-Boot cannot save you from doing all the necessary modifications to
3114configure the Linux device drivers for use with your target hardware
3115(no, we don't intend to provide a full virtual machine interface to
3116Linux :-).
3117
3118But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3119
3120Just make sure your machine specific header file (for instance
3121include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3122Information structure as we define in include/asm-<arch>/u-boot.h,
3123and make sure that your definition of IMAP_ADDR uses the same value
3124as your U-Boot configuration in CFG_IMMR.
3125
3126
3127Configuring the Linux kernel:
3128-----------------------------
3129
3130No specific requirements for U-Boot. Make sure you have some root
3131device (initial ramdisk, NFS) for your target system.
3132
3133
3134Building a Linux Image:
3135-----------------------
3136
3137With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3138not used. If you use recent kernel source, a new build target
3139"uImage" will exist which automatically builds an image usable by
3140U-Boot. Most older kernels also have support for a "pImage" target,
3141which was introduced for our predecessor project PPCBoot and uses a
3142100% compatible format.
3143
3144Example:
3145
3146        make TQM850L_config
3147        make oldconfig
3148        make dep
3149        make uImage
3150
3151The "uImage" build target uses a special tool (in 'tools/mkimage') to
3152encapsulate a compressed Linux kernel image with header  information,
3153CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3154
3155* build a standard "vmlinux" kernel image (in ELF binary format):
3156
3157* convert the kernel into a raw binary image:
3158
3159        ${CROSS_COMPILE}-objcopy -O binary \
3160                                 -R .note -R .comment \
3161                                 -S vmlinux linux.bin
3162
3163* compress the binary image:
3164
3165        gzip -9 linux.bin
3166
3167* package compressed binary image for U-Boot:
3168
3169        mkimage -A ppc -O linux -T kernel -C gzip \
3170                -a 0 -e 0 -n "Linux Kernel Image" \
3171                -d linux.bin.gz uImage
3172
3173
3174The "mkimage" tool can also be used to create ramdisk images for use
3175with U-Boot, either separated from the Linux kernel image, or
3176combined into one file. "mkimage" encapsulates the images with a 64
3177byte header containing information about target architecture,
3178operating system, image type, compression method, entry points, time
3179stamp, CRC32 checksums, etc.
3180
3181"mkimage" can be called in two ways: to verify existing images and
3182print the header information, or to build new images.
3183
3184In the first form (with "-l" option) mkimage lists the information
3185contained in the header of an existing U-Boot image; this includes
3186checksum verification:
3187
3188        tools/mkimage -l image
3189          -l ==> list image header information
3190
3191The second form (with "-d" option) is used to build a U-Boot image
3192from a "data file" which is used as image payload:
3193
3194        tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3195                      -n name -d data_file image
3196          -A ==> set architecture to 'arch'
3197          -O ==> set operating system to 'os'
3198          -T ==> set image type to 'type'
3199          -C ==> set compression type 'comp'
3200          -a ==> set load address to 'addr' (hex)
3201          -e ==> set entry point to 'ep' (hex)
3202          -n ==> set image name to 'name'
3203          -d ==> use image data from 'datafile'
3204
3205Right now, all Linux kernels for PowerPC systems use the same load
3206address (0x00000000), but the entry point address depends on the
3207kernel version:
3208
3209- 2.2.x kernels have the entry point at 0x0000000C,
3210- 2.3.x and later kernels have the entry point at 0x00000000.
3211
3212So a typical call to build a U-Boot image would read:
3213
3214        -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3215        > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3216        > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3217        > examples/uImage.TQM850L
3218        Image Name:   2.4.4 kernel for TQM850L
3219        Created:      Wed Jul 19 02:34:59 2000
3220        Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3221        Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3222        Load Address: 0x00000000
3223        Entry Point:  0x00000000
3224
3225To verify the contents of the image (or check for corruption):
3226
3227        -> tools/mkimage -l examples/uImage.TQM850L
3228        Image Name:   2.4.4 kernel for TQM850L
3229        Created:      Wed Jul 19 02:34:59 2000
3230        Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3231        Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3232        Load Address: 0x00000000
3233        Entry Point:  0x00000000
3234
3235NOTE: for embedded systems where boot time is critical you can trade
3236speed for memory and install an UNCOMPRESSED image instead: this
3237needs more space in Flash, but boots much faster since it does not
3238need to be uncompressed:
3239
3240        -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3241        -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3242        > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3243        > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3244        > examples/uImage.TQM850L-uncompressed
3245        Image Name:   2.4.4 kernel for TQM850L
3246        Created:      Wed Jul 19 02:34:59 2000
3247        Image Type:   PowerPC Linux Kernel Image (uncompressed)
3248        Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3249        Load Address: 0x00000000
3250        Entry Point:  0x00000000
3251
3252
3253Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3254when your kernel is intended to use an initial ramdisk:
3255
3256        -> tools/mkimage -n 'Simple Ramdisk Image' \
3257        > -A ppc -O linux -T ramdisk -C gzip \
3258        > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3259        Image Name:   Simple Ramdisk Image
3260        Created:      Wed Jan 12 14:01:50 2000
3261        Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3262        Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3263        Load Address: 0x00000000
3264        Entry Point:  0x00000000
3265
3266
3267Installing a Linux Image:
3268-------------------------
3269
3270To downloading a U-Boot image over the serial (console) interface,
3271you must convert the image to S-Record format:
3272
3273        objcopy -I binary -O srec examples/image examples/image.srec
3274
3275The 'objcopy' does not understand the information in the U-Boot
3276image header, so the resulting S-Record file will be relative to
3277address 0x00000000. To load it to a given address, you need to
3278specify the target address as 'offset' parameter with the 'loads'
3279command.
3280
3281Example: install the image to address 0x40100000 (which on the
3282TQM8xxL is in the first Flash bank):
3283
3284        => erase 40100000 401FFFFF
3285
3286        .......... done
3287        Erased 8 sectors
3288
3289        => loads 40100000
3290        ## Ready for S-Record download ...
3291        ~>examples/image.srec
3292        1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3293        ...
3294        15989 15990 15991 15992
3295        [file transfer complete]
3296        [connected]
3297        ## Start Addr = 0x00000000
3298
3299
3300You can check the success of the download using the 'iminfo' command;
3301this includes a checksum verification so you can be sure no data
3302corruption happened:
3303
3304        => imi 40100000
3305
3306        ## Checking Image at 40100000 ...
3307           Image Name:   2.2.13 for initrd on TQM850L
3308           Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3309           Data Size:    335725 Bytes = 327 kB = 0 MB
3310           Load Address: 00000000
3311           Entry Point:  0000000c
3312           Verifying Checksum ... OK
3313
3314
3315Boot Linux:
3316-----------
3317
3318The "bootm" command is used to boot an application that is stored in
3319memory (RAM or Flash). In case of a Linux kernel image, the contents
3320of the "bootargs" environment variable is passed to the kernel as
3321parameters. You can check and modify this variable using the
3322"printenv" and "setenv" commands:
3323
3324
3325        => printenv bootargs
3326        bootargs=root=/dev/ram
3327
3328        => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3329
3330        => printenv bootargs
3331        bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3332
3333        => bootm 40020000
3334        ## Booting Linux kernel at 40020000 ...
3335           Image Name:   2.2.13 for NFS on TQM850L
3336           Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3337           Data Size:    381681 Bytes = 372 kB = 0 MB
3338           Load Address: 00000000
3339           Entry Point:  0000000c
3340           Verifying Checksum ... OK
3341           Uncompressing Kernel Image ... OK
3342        Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
3343        Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3344        time_init: decrementer frequency = 187500000/60
3345        Calibrating delay loop... 49.77 BogoMIPS
3346        Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3347        ...
3348
3349If you want to boot a Linux kernel with initial RAM disk, you pass
3350the memory addresses of both the kernel and the initrd image (PPBCOOT
3351format!) to the "bootm" command:
3352
3353        => imi 40100000 40200000
3354
3355        ## Checking Image at 40100000 ...
3356           Image Name:   2.2.13 for initrd on TQM850L
3357           Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3358           Data Size:    335725 Bytes = 327 kB = 0 MB
3359           Load Address: 00000000
3360           Entry Point:  0000000c
3361           Verifying Checksum ... OK
3362
3363        ## Checking Image at 40200000 ...
3364           Image Name:   Simple Ramdisk Image
3365           Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3366           Data Size:    566530 Bytes = 553 kB = 0 MB
3367           Load Address: 00000000
3368           Entry Point:  00000000
3369           Verifying Checksum ... OK
3370
3371        => bootm 40100000 40200000
3372        ## Booting Linux kernel at 40100000 ...
3373           Image Name:   2.2.13 for initrd on TQM850L
3374           Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3375           Data Size:    335725 Bytes = 327 kB = 0 MB
3376           Load Address: 00000000
3377           Entry Point:  0000000c
3378           Verifying Checksum ... OK
3379           Uncompressing Kernel Image ... OK
3380        ## Loading RAMDisk Image at 40200000 ...
3381           Image Name:   Simple Ramdisk Image
3382           Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3383           Data Size:    566530 Bytes = 553 kB = 0 MB
3384           Load Address: 00000000
3385           Entry Point:  00000000
3386           Verifying Checksum ... OK
3387           Loading Ramdisk ... OK
3388        Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
3389        Boot arguments: root=/dev/ram
3390        time_init: decrementer frequency = 187500000/60
3391        Calibrating delay loop... 49.77 BogoMIPS
3392        ...
3393        RAMDISK: Compressed image found at block 0
3394        VFS: Mounted root (ext2 filesystem).
3395
3396        bash#
3397
3398Boot Linux and pass a flat device tree:
3399-----------
3400
3401First, U-Boot must be compiled with the appropriate defines. See the section
3402titled "Linux Kernel Interface" above for a more in depth explanation. The
3403following is an example of how to start a kernel and pass an updated
3404flat device tree:
3405
3406=> print oftaddr
3407oftaddr=0x300000
3408=> print oft
3409oft=oftrees/mpc8540ads.dtb
3410=> tftp $oftaddr $oft
3411Speed: 1000, full duplex
3412Using TSEC0 device
3413TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3414Filename 'oftrees/mpc8540ads.dtb'.
3415Load address: 0x300000
3416Loading: #
3417done
3418Bytes transferred = 4106 (100a hex)
3419=> tftp $loadaddr $bootfile
3420Speed: 1000, full duplex
3421Using TSEC0 device
3422TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3423Filename 'uImage'.
3424Load address: 0x200000
3425Loading:############
3426done
3427Bytes transferred = 1029407 (fb51f hex)
3428=> print loadaddr
3429loadaddr=200000
3430=> print oftaddr
3431oftaddr=0x300000
3432=> bootm $loadaddr - $oftaddr
3433## Booting image at 00200000 ...
3434   Image Name:   Linux-2.6.17-dirty
3435   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3436   Data Size:    1029343 Bytes = 1005.2 kB
3437   Load Address: 00000000
3438   Entry Point:  00000000
3439   Verifying Checksum ... OK
3440   Uncompressing Kernel Image ... OK
3441Booting using flat device tree at 0x300000
3442Using MPC85xx ADS machine description
3443Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3444[snip]
3445
3446
3447More About U-Boot Image Types:
3448------------------------------
3449
3450U-Boot supports the following image types:
3451
3452   "Standalone Programs" are directly runnable in the environment
3453        provided by U-Boot; it is expected that (if they behave
3454        well) you can continue to work in U-Boot after return from
3455        the Standalone Program.
3456   "OS Kernel Images" are usually images of some Embedded OS which
3457        will take over control completely. Usually these programs
3458        will install their own set of exception handlers, device
3459        drivers, set up the MMU, etc. - this means, that you cannot
3460        expect to re-enter U-Boot except by resetting the CPU.
3461   "RAMDisk Images" are more or less just data blocks, and their
3462        parameters (address, size) are passed to an OS kernel that is
3463        being started.
3464   "Multi-File Images" contain several images, typically an OS
3465        (Linux) kernel image and one or more data images like
3466        RAMDisks. This construct is useful for instance when you want
3467        to boot over the network using BOOTP etc., where the boot
3468        server provides just a single image file, but you want to get
3469        for instance an OS kernel and a RAMDisk image.
3470
3471        "Multi-File Images" start with a list of image sizes, each
3472        image size (in bytes) specified by an "uint32_t" in network
3473        byte order. This list is terminated by an "(uint32_t)0".
3474        Immediately after the terminating 0 follow the images, one by
3475        one, all aligned on "uint32_t" boundaries (size rounded up to
3476        a multiple of 4 bytes).
3477
3478   "Firmware Images" are binary images containing firmware (like
3479        U-Boot or FPGA images) which usually will be programmed to
3480        flash memory.
3481
3482   "Script files" are command sequences that will be executed by
3483        U-Boot's command interpreter; this feature is especially
3484        useful when you configure U-Boot to use a real shell (hush)
3485        as command interpreter.
3486
3487
3488Standalone HOWTO:
3489=================
3490
3491One of the features of U-Boot is that you can dynamically load and
3492run "standalone" applications, which can use some resources of
3493U-Boot like console I/O functions or interrupt services.
3494
3495Two simple examples are included with the sources:
3496
3497"Hello World" Demo:
3498-------------------
3499
3500'examples/hello_world.c' contains a small "Hello World" Demo
3501application; it is automatically compiled when you build U-Boot.
3502It's configured to run at address 0x00040004, so you can play with it
3503like that:
3504
3505        => loads
3506        ## Ready for S-Record download ...
3507        ~>examples/hello_world.srec
3508        1 2 3 4 5 6 7 8 9 10 11 ...
3509        [file transfer complete]
3510        [connected]
3511        ## Start Addr = 0x00040004
3512
3513        => go 40004 Hello World! This is a test.
3514        ## Starting application at 0x00040004 ...
3515        Hello World
3516        argc = 7
3517        argv[0] = "40004"
3518        argv[1] = "Hello"
3519        argv[2] = "World!"
3520        argv[3] = "This"
3521        argv[4] = "is"
3522        argv[5] = "a"
3523        argv[6] = "test."
3524        argv[7] = "<NULL>"
3525        Hit any key to exit ...
3526
3527        ## Application terminated, rc = 0x0
3528
3529Another example, which demonstrates how to register a CPM interrupt
3530handler with the U-Boot code, can be found in 'examples/timer.c'.
3531Here, a CPM timer is set up to generate an interrupt every second.
3532The interrupt service routine is trivial, just printing a '.'
3533character, but this is just a demo program. The application can be
3534controlled by the following keys:
3535
3536        ? - print current values og the CPM Timer registers
3537        b - enable interrupts and start timer
3538        e - stop timer and disable interrupts
3539        q - quit application
3540
3541        => loads
3542        ## Ready for S-Record download ...
3543        ~>examples/timer.srec
3544        1 2 3 4 5 6 7 8 9 10 11 ...
3545        [file transfer complete]
3546        [connected]
3547        ## Start Addr = 0x00040004
3548
3549        => go 40004
3550        ## Starting application at 0x00040004 ...
3551        TIMERS=0xfff00980
3552        Using timer 1
3553          tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3554
3555Hit 'b':
3556        [q, b, e, ?] Set interval 1000000 us
3557        Enabling timer
3558Hit '?':
3559        [q, b, e, ?] ........
3560        tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3561Hit '?':
3562        [q, b, e, ?] .
3563        tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3564Hit '?':
3565        [q, b, e, ?] .
3566        tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3567Hit '?':
3568        [q, b, e, ?] .
3569        tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3570Hit 'e':
3571        [q, b, e, ?] ...Stopping timer
3572Hit 'q':
3573        [q, b, e, ?] ## Application terminated, rc = 0x0
3574
3575
3576Minicom warning:
3577================
3578
3579Over time, many people have reported problems when trying to use the
3580"minicom" terminal emulation program for serial download. I (wd)
3581consider minicom to be broken, and recommend not to use it. Under
3582Unix, I recommend to use C-Kermit for general purpose use (and
3583especially for kermit binary protocol download ("loadb" command), and
3584use "cu" for S-Record download ("loads" command).
3585
3586Nevertheless, if you absolutely want to use it try adding this
3587configuration to your "File transfer protocols" section:
3588
3589           Name    Program                      Name U/D FullScr IO-Red. Multi
3590        X  kermit  /usr/bin/kermit -i -l %l -s   Y    U    Y       N      N
3591        Y  kermit  /usr/bin/kermit -i -l %l -r   N    D    Y       N      N
3592
3593
3594NetBSD Notes:
3595=============
3596
3597Starting at version 0.9.2, U-Boot supports NetBSD both as host
3598(build U-Boot) and target system (boots NetBSD/mpc8xx).
3599
3600Building requires a cross environment; it is known to work on
3601NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3602need gmake since the Makefiles are not compatible with BSD make).
3603Note that the cross-powerpc package does not install include files;
3604attempting to build U-Boot will fail because <machine/ansi.h> is
3605missing.  This file has to be installed and patched manually:
3606
3607        # cd /usr/pkg/cross/powerpc-netbsd/include
3608        # mkdir powerpc
3609        # ln -s powerpc machine
3610        # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3611        # ${EDIT} powerpc/ansi.h        ## must remove __va_list, _BSD_VA_LIST
3612
3613Native builds *don't* work due to incompatibilities between native
3614and U-Boot include files.
3615
3616Booting assumes that (the first part of) the image booted is a
3617stage-2 loader which in turn loads and then invokes the kernel
3618proper. Loader sources will eventually appear in the NetBSD source
3619tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3620meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3621
3622
3623Implementation Internals:
3624=========================
3625
3626The following is not intended to be a complete description of every
3627implementation detail. However, it should help to understand the
3628inner workings of U-Boot and make it easier to port it to custom
3629hardware.
3630
3631
3632Initial Stack, Global Data:
3633---------------------------
3634
3635The implementation of U-Boot is complicated by the fact that U-Boot
3636starts running out of ROM (flash memory), usually without access to
3637system RAM (because the memory controller is not initialized yet).
3638This means that we don't have writable Data or BSS segments, and BSS
3639is not initialized as zero. To be able to get a C environment working
3640at all, we have to allocate at least a minimal stack. Implementation
3641options for this are defined and restricted by the CPU used: Some CPU
3642models provide on-chip memory (like the IMMR area on MPC8xx and
3643MPC826x processors), on others (parts of) the data cache can be
3644locked as (mis-) used as memory, etc.
3645
3646        Chris Hallinan posted a good summary of these issues to the
3647        u-boot-users mailing list:
3648
3649        Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3650        From: "Chris Hallinan" <clh@net1plus.com>
3651        Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3652        ...
3653
3654        Correct me if I'm wrong, folks, but the way I understand it
3655        is this: Using DCACHE as initial RAM for Stack, etc, does not
3656        require any physical RAM backing up the cache. The cleverness
3657        is that the cache is being used as a temporary supply of
3658        necessary storage before the SDRAM controller is setup. It's
3659        beyond the scope of this list to explain the details, but you
3660        can see how this works by studying the cache architecture and
3661        operation in the architecture and processor-specific manuals.
3662
3663        OCM is On Chip Memory, which I believe the 405GP has 4K. It
3664        is another option for the system designer to use as an
3665        initial stack/RAM area prior to SDRAM being available. Either
3666        option should work for you. Using CS 4 should be fine if your
3667        board designers haven't used it for something that would
3668        cause you grief during the initial boot! It is frequently not
3669        used.
3670
3671        CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3672        with your processor/board/system design. The default value
3673        you will find in any recent u-boot distribution in
3674        walnut.h should work for you. I'd set it to a value larger
3675        than your SDRAM module. If you have a 64MB SDRAM module, set
3676        it above 400_0000. Just make sure your board has no resources
3677        that are supposed to respond to that address! That code in
3678        start.S has been around a while and should work as is when
3679        you get the config right.
3680
3681        -Chris Hallinan
3682        DS4.COM, Inc.
3683
3684It is essential to remember this, since it has some impact on the C
3685code for the initialization procedures:
3686
3687* Initialized global data (data segment) is read-only. Do not attempt
3688  to write it.
3689
3690* Do not use any uninitialized global data (or implicitely initialized
3691  as zero data - BSS segment) at all - this is undefined, initiali-
3692  zation is performed later (when relocating to RAM).
3693
3694* Stack space is very limited. Avoid big data buffers or things like
3695  that.
3696
3697Having only the stack as writable memory limits means we cannot use
3698normal global data to share information beween the code. But it
3699turned out that the implementation of U-Boot can be greatly
3700simplified by making a global data structure (gd_t) available to all
3701functions. We could pass a pointer to this data as argument to _all_
3702functions, but this would bloat the code. Instead we use a feature of
3703the GCC compiler (Global Register Variables) to share the data: we
3704place a pointer (gd) to the global data into a register which we
3705reserve for this purpose.
3706
3707When choosing a register for such a purpose we are restricted by the
3708relevant  (E)ABI  specifications for the current architecture, and by
3709GCC's implementation.
3710
3711For PowerPC, the following registers have specific use:
3712        R1:     stack pointer
3713        R2:     reserved for system use
3714        R3-R4:  parameter passing and return values
3715        R5-R10: parameter passing
3716        R13:    small data area pointer
3717        R30:    GOT pointer
3718        R31:    frame pointer
3719
3720        (U-Boot also uses R14 as internal GOT pointer.)
3721
3722    ==> U-Boot will use R2 to hold a pointer to the global data
3723
3724    Note: on PPC, we could use a static initializer (since the
3725    address of the global data structure is known at compile time),
3726    but it turned out that reserving a register results in somewhat
3727    smaller code - although the code savings are not that big (on
3728    average for all boards 752 bytes for the whole U-Boot image,
3729    624 text + 127 data).
3730
3731On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3732        http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3733
3734    ==> U-Boot will use P5 to hold a pointer to the global data
3735
3736On ARM, the following registers are used:
3737
3738        R0:     function argument word/integer result
3739        R1-R3:  function argument word
3740        R9:     GOT pointer
3741        R10:    stack limit (used only if stack checking if enabled)
3742        R11:    argument (frame) pointer
3743        R12:    temporary workspace
3744        R13:    stack pointer
3745        R14:    link register
3746        R15:    program counter
3747
3748    ==> U-Boot will use R8 to hold a pointer to the global data
3749
3750NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3751or current versions of GCC may "optimize" the code too much.
3752
3753Memory Management:
3754------------------
3755
3756U-Boot runs in system state and uses physical addresses, i.e. the
3757MMU is not used either for address mapping nor for memory protection.
3758
3759The available memory is mapped to fixed addresses using the memory
3760controller. In this process, a contiguous block is formed for each
3761memory type (Flash, SDRAM, SRAM), even when it consists of several
3762physical memory banks.
3763
3764U-Boot is installed in the first 128 kB of the first Flash bank (on
3765TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3766booting and sizing and initializing DRAM, the code relocates itself
3767to the upper end of DRAM. Immediately below the U-Boot code some
3768memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3769configuration setting]. Below that, a structure with global Board
3770Info data is placed, followed by the stack (growing downward).
3771
3772Additionally, some exception handler code is copied to the low 8 kB
3773of DRAM (0x00000000 ... 0x00001FFF).
3774
3775So a typical memory configuration with 16 MB of DRAM could look like
3776this:
3777
3778        0x0000 0000     Exception Vector code
3779              :
3780        0x0000 1FFF
3781        0x0000 2000     Free for Application Use
3782              :
3783              :
3784
3785              :
3786              :
3787        0x00FB FF20     Monitor Stack (Growing downward)
3788        0x00FB FFAC     Board Info Data and permanent copy of global data
3789        0x00FC 0000     Malloc Arena
3790              :
3791        0x00FD FFFF
3792        0x00FE 0000     RAM Copy of Monitor Code
3793        ...             eventually: LCD or video framebuffer
3794        ...             eventually: pRAM (Protected RAM - unchanged by reset)
3795        0x00FF FFFF     [End of RAM]
3796
3797
3798System Initialization:
3799----------------------
3800
3801In the reset configuration, U-Boot starts at the reset entry point
3802(on most PowerPC systems at address 0x00000100). Because of the reset
3803configuration for CS0# this is a mirror of the onboard Flash memory.
3804To be able to re-map memory U-Boot then jumps to its link address.
3805To be able to implement the initialization code in C, a (small!)
3806initial stack is set up in the internal Dual Ported RAM (in case CPUs
3807which provide such a feature like MPC8xx or MPC8260), or in a locked
3808part of the data cache. After that, U-Boot initializes the CPU core,
3809the caches and the SIU.
3810
3811Next, all (potentially) available memory banks are mapped using a
3812preliminary mapping. For example, we put them on 512 MB boundaries
3813(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3814on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3815programmed for SDRAM access. Using the temporary configuration, a
3816simple memory test is run that determines the size of the SDRAM
3817banks.
3818
3819When there is more than one SDRAM bank, and the banks are of
3820different size, the largest is mapped first. For equal size, the first
3821bank (CS2#) is mapped first. The first mapping is always for address
38220x00000000, with any additional banks following immediately to create
3823contiguous memory starting from 0.
3824
3825Then, the monitor installs itself at the upper end of the SDRAM area
3826and allocates memory for use by malloc() and for the global Board
3827Info data; also, the exception vector code is copied to the low RAM
3828pages, and the final stack is set up.
3829
3830Only after this relocation will you have a "normal" C environment;
3831until that you are restricted in several ways, mostly because you are
3832running from ROM, and because the code will have to be relocated to a
3833new address in RAM.
3834
3835
3836U-Boot Porting Guide:
3837----------------------
3838
3839[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3840list, October 2002]
3841
3842
3843int main (int argc, char *argv[])
3844{
3845        sighandler_t no_more_time;
3846
3847        signal (SIGALRM, no_more_time);
3848        alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3849
3850        if (available_money > available_manpower) {
3851                pay consultant to port U-Boot;
3852                return 0;
3853        }
3854
3855        Download latest U-Boot source;
3856
3857        Subscribe to u-boot-users mailing list;
3858
3859        if (clueless) {
3860                email ("Hi, I am new to U-Boot, how do I get started?");
3861        }
3862
3863        while (learning) {
3864                Read the README file in the top level directory;
3865                Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3866                Read the source, Luke;
3867        }
3868
3869        if (available_money > toLocalCurrency ($2500)) {
3870                Buy a BDI2000;
3871        } else {
3872                Add a lot of aggravation and time;
3873        }
3874
3875        Create your own board support subdirectory;
3876
3877        Create your own board config file;
3878
3879        while (!running) {
3880                do {
3881                        Add / modify source code;
3882                } until (compiles);
3883                Debug;
3884                if (clueless)
3885                        email ("Hi, I am having problems...");
3886        }
3887        Send patch file to Wolfgang;
3888
3889        return 0;
3890}
3891
3892void no_more_time (int sig)
3893{
3894      hire_a_guru();
3895}
3896
3897
3898Coding Standards:
3899-----------------
3900
3901All contributions to U-Boot should conform to the Linux kernel
3902coding style; see the file "Documentation/CodingStyle" and the script
3903"scripts/Lindent" in your Linux kernel source directory.  In sources
3904originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3905spaces before parameters to function calls) is actually used.
3906
3907Source files originating from a different project (for example the
3908MTD subsystem) are generally exempt from these guidelines and are not
3909reformated to ease subsequent migration to newer versions of those
3910sources.
3911
3912Please note that U-Boot is implemented in C (and to some small parts in
3913Assembler); no C++ is used, so please do not use C++ style comments (//)
3914in your code.
3915
3916Please also stick to the following formatting rules:
3917- remove any trailing white space
3918- use TAB characters for indentation, not spaces
3919- make sure NOT to use DOS '\r\n' line feeds
3920- do not add more than 2 empty lines to source files
3921- do not add trailing empty lines to source files
3922
3923Submissions which do not conform to the standards may be returned
3924with a request to reformat the changes.
3925
3926
3927Submitting Patches:
3928-------------------
3929
3930Since the number of patches for U-Boot is growing, we need to
3931establish some rules. Submissions which do not conform to these rules
3932may be rejected, even when they contain important and valuable stuff.
3933
3934Patches shall be sent to the u-boot-users mailing list.
3935
3936Please see http://www.denx.de/wiki/U-Boot/Patches for details.
3937
3938When you send a patch, please include the following information with
3939it:
3940
3941* For bug fixes: a description of the bug and how your patch fixes
3942  this bug. Please try to include a way of demonstrating that the
3943  patch actually fixes something.
3944
3945* For new features: a description of the feature and your
3946  implementation.
3947
3948* A CHANGELOG entry as plaintext (separate from the patch)
3949
3950* For major contributions, your entry to the CREDITS file
3951
3952* When you add support for a new board, don't forget to add this
3953  board to the MAKEALL script, too.
3954
3955* If your patch adds new configuration options, don't forget to
3956  document these in the README file.
3957
3958* The patch itself. If you are using git (which is *strongly*
3959  recommended) you can easily generate the patch using the
3960  "git-format-patch". If you then use "git-send-email" to send it to
3961  the U-Boot mailing list, you will avoid most of the common problems
3962  with some other mail clients.
3963
3964  If you cannot use git, use "diff -purN OLD NEW". If your version of
3965  diff does not support these options, then get the latest version of
3966  GNU diff.
3967
3968  The current directory when running this command shall be the parent
3969  directory of the U-Boot source tree (i. e. please make sure that
3970  your patch includes sufficient directory information for the
3971  affected files).
3972
3973  We prefer patches as plain text. MIME attachments are discouraged,
3974  and compressed attachments must not be used.
3975
3976* If one logical set of modifications affects or creates several
3977  files, all these changes shall be submitted in a SINGLE patch file.
3978
3979* Changesets that contain different, unrelated modifications shall be
3980  submitted as SEPARATE patches, one patch per changeset.
3981
3982
3983Notes:
3984
3985* Before sending the patch, run the MAKEALL script on your patched
3986  source tree and make sure that no errors or warnings are reported
3987  for any of the boards.
3988
3989* Keep your modifications to the necessary minimum: A patch
3990  containing several unrelated changes or arbitrary reformats will be
3991  returned with a request to re-formatting / split it.
3992
3993* If you modify existing code, make sure that your new code does not
3994  add to the memory footprint of the code ;-) Small is beautiful!
3995  When adding new features, these should compile conditionally only
3996  (using #ifdef), and the resulting code with the new feature
3997  disabled must not need more memory than the old code without your
3998  modification.
3999
4000* Remember that there is a size limit of 40 kB per message on the
4001  u-boot-users mailing list. Bigger patches will be moderated. If
4002  they are reasonable and not bigger than 100 kB, they will be
4003  acknowledged. Even bigger patches should be avoided.
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