Changes between Version 6 and Version 7 of venice/bsp

Timestamp:

09/10/2021 10:35:54 PM (3 years ago)

Author:

Tim Harvey

Comment:

add toolchain details and cross-compile examples

venice/bsp

@@ -116 +116 @@
 make ubuntu-image
 }}}
+
+
+[=#toolchain]
+== Toolchain
+
+=== Buildroot based toolchain
+The Venice BSP uses buildroot to build the toolchain used to build the kernel and bootloader firmware.
+
+The buidlroot config is [https://github.com/Gateworks/bsp-venice/blob/master/buildroot-imx8mm_venice_defconfig venice/buildroot-imx8mm_venice_defconfig] which is copied to buildroot/configs/imx8mm_venice_defconfig.
+
+The bsp [https://github.com/Gateworks/bsp-venice/blob/master/Makefile Makefile] has a 'toolchain' target which is built as a pre-requisite for building the bootloader and kernel.
+
+The buildroot version is 2020.05.3 and builds a toolchain with the following details (which are all defaults for buildroot):
+ - Linux 5.6.x kernel headers
+ - uClibc libc
+ - binutils 2.32
+ - gcc 8.x
+ - C++ support (default is to disable this; we enable it)
+
+The specific details can be shown by running 'gcc -v' for example:
+{{{#!bash
+user@host:/usr/src/venice/bsp$ . ./setup-environment # configure PATH and CROSS_COMPILER env vars
+user@host:/usr/src/venice/bsp$ ${CROSS_COMPILE}gcc -v
+Using built-in specs.
+COLLECT_GCC=/usr/src/venice/bsp/buildroot/output/host/bin/aarch64-linux-gcc.br_real
+COLLECT_LTO_WRAPPER=/usr/src/venice/bsp/buildroot/output/host/libexec/gcc/aarch64-buildroot-linux-uclibc/8.4.0/lto-wrapper
+Target: aarch64-buildroot-linux-uclibc
+Configured with: ./configure --prefix=/usr/src/venice/bsp/buildroot/output/host --sysconfdir=/usr/src/venice/bsp/buildroot/output/host/etc --enable-static --target=aarch64-buildroot-linux-uclibc --with-sysroot=/usr/src/venice/bsp/buildroot/output/host/aarch64-buildroot-linux-uclibc/sysroot --enable-__cxa_atexit --with-gnu-ld --disable-libssp --disable-multilib --disable-decimal-float --with-gmp=/usr/src/venice/bsp/buildroot/output/host --with-mpc=/usr/src/venice/bsp/buildroot/output/host --with-mpfr=/usr/src/venice/bsp/buildroot/output/host --with-pkgversion='Buildroot 2020.05.3' --with-bugurl=http://bugs.buildroot.net/ --disable-libquadmath --disable-libsanitizer --enable-tls --enable-threads --without-isl --without-cloog --with-abi=lp64 --with-cpu=cortex-a53 --enable-languages=c,c++ --with-build-time-tools=/usr/src/venice/bsp/buildroot/output/host/aarch64-buildroot-linux-uclibc/bin --enable-shared --disable-libgomp
+Thread model: posix
+gcc version 8.4.0 (Buildroot 2020.05.3)
+}}}
+
+
+Note there are other options you may want to change for your needs such as using a different libc, different compiler version, or enable WCHAR support or additional threading support. To do so you can:
+{{{#!bash
+cd buildroot
+make menuconfig # select options desired under Toolchain
+make clean
+make 
+}}}
+ * make sure you clean and rebuild when changing toolchain options
+
+The buildroot based toolchain is used by virtue of sourcing the [https://github.com/Gateworks/bsp-venice/blob/master/setup-environment setup-environment] file which adds to your PATH and sets the CROSS_COMPILE variable.
+
+=== External toolchain
+The Venice BSP uses buildroot to build the toolchain used to build the kernel and bootloader firmware.
+
+While the BSP makefile will always build the buildroot toolchain (unless you comment that out in the Makefile) you can easily use a toolchain of your liking by modifying the environment like 'setup-environment' does. Simply make sure to set CROSS_COMPILE to the prefix of your toolchains 'gcc' compiler and other tools, and make sure your external toolchain shows up first in your PATH.
+
+
+=== Cross compile examples
+
+Examples of cross-compiling:
+ * ANSI-C hello world:
+{{{#!bash
+cat << EOF > helloworld.c
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv)
+{
+        printf("hello world!\n");
+
+        return 0;
+}
+EOF
+. ./setup-environment # setup environment for buildroot toolchain
+${CROSS_COMPILE}gcc helloworld.c -o helloworld
+}}}
+ * C++ hello world:
+{{{#!bash
+cat << EOF > helloworld.cpp
+#include <iostream>
+
+using namespace std;
+
+int main() {
+        cout << "Hello World!";
+        return 0;
+}
+EOF
+. ./setup-environment # setup environment for buildroot toolchain
+${CROSS_COMPILE}gcc helloworld.cpp -lstdc++ -o helloworld
+}}}
+ * kernel module:
+{{{#!bash
+. ./setup-environment # setup environment for buildroot toolchain
+make kernel_image # first build the kernel
+make -C linux M=$PWD/my-module modules
+}}}
+  - Note that some out-of-tree kernel modules do not follow the suggested Makefile standards and may need to be modified to use the CROSS_COMPILE prefix and/or specify the kernel directory (as opposed to the above example where you do a make in the linux dir and set M to the path of your module)
+
+
 = SSH using Ubuntu