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Venice U-Boot Bootloader
Gateworks supports the U-Boot Bootloader for the Venice product family.
The purpose of a bootloader is to load the Linux kernel and execute it passing it configuration parameters such as an optional kernel command-line, an optional initial ramdisk filesystem, and a device-tree.
The following items are supported in the Gateworks U-Boot for Venice:
- IMX8M FEC GbE
- IMX8MP EQOS GbE
- USB Host support (USB Mass Storage and USB Networking for ASIX USB 2.0 USB Network device)
- eMMC / microSD
The following items are not currently supported in the Gateworks U-Boot for Venice:
- PCIe support (include PCIe based Gbe)
Additional resources:
see uboot for more info
Editing the environment
If you would like to modify the default environment you can edit the venice/venice.env in the Venice BSP.
Restoring environment defaults
The Venice boot firmware has a copy of the original U-Boot env that was created during build time.
To restore default bootloader environment variables:
- At the "Hit any key to stop autoboot:" prompt press any key.
- Execute the following command:
run restore_env && reset
Boot Devices
The Venice U-Boot Bootloader supports the following devices and partition types:
- eMMC
- microSD
- USB Mass Storage
- NVMe
The U-Boot 'Generic Distro Config' is used for Venice:
- the default bootcmd will ultimately search for boot scripts on a set of bootable devices
- the 'boot_targets' env variable dictates which devices are checked and in what order
- the 'boot_prefixes' env variable dictates what file prefixes are searched for a boot script
- the 'boot_scripts' env variable dictates what bootscript names are searched for
- only partitions that have the 'boot' flag set are looked at for boot scripts
Venice boards are configured via one-time-programable fuses to boot to an on-board eMMC device (it is possible to have Gateworks configure a board to boot to microSD instead for a special or custom build).
If you wish to select a different boot device priority you can adjust boot_targets. For example:
- boot from NVMe (nvme dev 0)
# flash your disk image to the NVMe device u-boot=> pci enum PCIE-0: Link up (Gen1-x1, Bus0) u-boot=> nvme scan u-boot=> nvme info Device 0: Vendor: 0x10ec Rev: 0426-D00 Prod: 60272-0005 Type: Hard Disk Capacity: 57241.8 MB = 55.9 GB (117231408 x 512) u-boot=> tftpboot $loadaddr venice/jammy-venice.img.gz && gzwrite nvme 0 $loadaddr $filesize ... # set boot targets to boot only from nvme setenv boot_targets nvme0 saveenv
- boot from microSD (mmc dev 1)
u-boot=> mmc dev 1 switch to partitions #0, OK mmc1 is current device u-boot=> mmc list FSL_SDHC: 0 FSL_SDHC: 1 (SD) FSL_SDHC: 2 (eMMC) u-boot=> tftpboot $loadaddr venice/jammy-venice.img.gz && gzwrite mmc 1 $loadaddr $filesize ... # set boot targets to boot only from nvme setenv boot_targets mmc1 saveenv
- boot from USB 0 (usb dev 0)
u-boot=> usb start starting USB... Bus usb@38100000: Register 2000140 NbrPorts 2 Starting the controller USB XHCI 1.10 Bus usb@38200000: Register 2000140 NbrPorts 2 Starting the controller USB XHCI 1.10 scanning bus usb@38100000 for devices... cannot reset port 1!? 2 USB Device(s) found scanning bus usb@38200000 for devices... 4 USB Device(s) found scanning usb for storage devices... 1 Storage Device(s) found u-boot=> usb storage Device 0: Vendor: ASolid Rev: Prod: USB Type: Removable Hard Disk Capacity: 60000.0 MB = 58.5 GB (122880001 x 512) u-boot=> tftpboot $loadaddr venice/jammy-venice.img.gz && gzwrite usb 0 $loadaddr $filesize ... # set boot targets to boot only from nvme setenv boot_targets mmc1 saveenv
Memory Mapping
When working with boot firmware you are often dealing with choosing where to load in memory various components. Sometimes this is done by hard-coding addresses into U-Boot commands, using env variables, or hard coding them into the U-Boot build configuration files (ie binman node) or FIT image templates.
Here is what we recommend for memory mapping on the IMX8M{M,N,P} SoC's:
| address | var | Note |
|---|---|---|
| 0x00920000 | ARM Trusted Firmware | |
| 0x40000000 | base of DRAM | |
| 0x40200000 | kernel_comp_addr_r | CONFIG_TEXT_BASE: base of non-secure memory<BR>The ATF configures the first 2M of DRAM as secure for itself |
| 0x40310000 | binman_fip image gets put here | |
| 0x44000000 | CONFIG_SPL_LOAD_FIT_ADDRESS (used for secure boot) | |
| 0x48200000 | loadaddr, kernel_addr_r | CONFIG_SYS_LOAD_ADDR |
| 0x50200000 | fdt_addr_r | area for loading fdt (128M above kernel_addr_r) |
| 0x50300000 | scriptaddr | area for loading script (512K above fdt_addr_r) |
| 0x7e000000 | CFG_TZDRAM_START (secure boot with TEE; for 1GB DRAM boards) | |
| 0x80000000 | 1GB boundary | |
| 0xbe000000 | CFG_TZDRAM_START (secure boot with TEE; for 2GB DRAM boards) | |
| 0xc0000000 | 2GB boundary | |
| 0xfe000000 | CGG_TZDRAM_START (secure boot with TEE; for 4GB DRAM boards) | |
| 0x100000000 | 3GB boundary | |
| 0x140000000 | 4GB boundary |
