Ttyjfyk

I'm trying to build an older version of GCC toolchain for ARM under x86 because there is a bug with GCC > v5 for Cortex-M0. I'm following the combination of the following instructions:

• https://stackoverflow.com/a/10662297/1952991


• https://stackoverflow.com/q/24559878/1952991

So my overall procedure is as follows:

# Download GCC-5.5.0 from https://gcc.gnu.org/releases.html
VERSION="5.5.0"
tar xzf gcc-$VERSION.tar.gz
cd gcc-$VERSION
./contrib/download_prerequisites
cd ..
mkdir objdir
cd objdir
../gcc-5.5.0/configure --prefix=$HOME/embedded/gcc-arm-none-eabi-5.5.0 --disable-multilib --enable-languages=c,c++ --target=arm-none-eabi
make -j$(nproc) # use all cores
make install

Then the following files are created under ~/embedded/arm-none-eabi-5.5.0/bin/:

arm-none-eabi-c++ arm-none-eabi-gcc-5.5.0 arm-none-eabi-gcov
arm-none-eabi-cpp arm-none-eabi-gcc-ar arm-none-eabi-gcov-dump
arm-none-eabi-g++ arm-none-eabi-gcc-nm arm-none-eabi-gcov-tool
arm-none-eabi-gcc arm-none-eabi-gcc-ranlib

However, the following command fails:

arm-none-eabi-gcc -c -mcpu=cortex-m0 -O0 -ggdb (......)

Compiling crt0_v6m.S
as: unrecognized option '-mcpu=cortex-m0'
make: *** [/home/ceremcem/ChibiOS/os/common/startup/ARMCMx/compilers/GCC/rules.mk:253: build/obj/crt0_v6m.o] Error 1

I can verify that the command uses newly produced binaries:

$ which arm-none-eabi-gcc
/home/ceremcem/embedded/arm-none-eabi-5.5.0/bin//arm-none-eabi-gcc

This means that the newly compiled GCC toolchain does not accept the mcpu option. What could be wrong with building the GCC toolchain phase that causes -mcpu=cortex-m0 option to fail?

Your GCC doesn’t appear to be using the right as, and probably wouldn’t use the right ld either; you need to add

--with-as=/usr/bin/arm-none-eabi-as --with-ld=/usr/bin/arm-none-eabi-ld

to your ./configure line.

You’re also likely to run into issues related to Debian’s multi-arch approach, which GCC 5 doesn’t support directly. Your best bet is to download the last Debian package of GCC 5.5 in source form, and use that (with patches) to build your cross-compiler. Then it will use the ARM C library which was installed as a dependency of the cross-GCC package you installed.

dget https://snapshot.debian.org/archive/debian-debug/20180412T094604Z/pool/main/g/gcc-5/gcc-5_5.5.0-12.dsc
cd gcc-5-5.5.0
debian/rules patch

then configure and build as before. (Ignore the cross-building documentation in debian/README.cross.)