Trying to compile gcc 5.2.0 for ARM Cortex-M4

[Kyrill Tkachov]

On 13/11/15 15:13, Simon Wright wrote:
> On 13 Nov 2015, at 13:07, Johannes Bauer <dfnsonfsduifb@gmx.de> wrote:
>> Hi list,
>>
>> I'm trying to compile gcc 5.2.0 for a ARM Cortex-M4 target (on top of
>> binutils-2.25.1). This is the configure command I use to configure gcc:
>>
>> ../configure --prefix=/home/joe/bin/gcc/arm-cm4-bare/ --without-headers
>> --with-gnu-ld --with-gnu-as --with-dwarf2 --disable-werror
>> --disable-threads --disable-nls --disable-shared --disable-libssp
>> --disable-libmudflap --disable-libgomp --target=arm-none-eabi
>> --with-newlib --with-tune=cortex-m4 --disable-interwork
>> --disable-multilib --with-fpu=fpv4-sp-d16 --with-float=hard
>> --with-mode=thumb --enable-languages=c --with-system-zlib
>> --enable-target-optspace
>>
>> Unfortunately, the build fails:
>>
>> checking for suffix of object files... configure: error: in
>> `/home/joe/work/gcc/gcc/gcc-5.2.0/build/arm-none-eabi/libgcc':
>> configure: error: cannot compute suffix of object files: cannot compile
>> See `config.log' for more details.
>> make[1]: *** [configure-target-libgcc] Error 1
>>
>> This message is a bit misleading. config.log has the reason:
>>
>> configure:3464: /home/joe/work/gcc/gcc/gcc-5.2.0/build/./gcc/xgcc
>> -B/home/joe/work/gcc/gcc/gcc-5.2.0/build/./gcc/
>> -B/home/joe/bin/gcc/arm-cm4-bare/arm-none-eabi/bin/
>> -B/home/joe/bin/gcc/arm-cm4-bare/arm-none-eabi/lib/ -isystem
>> /home/joe/bin/gcc/arm-cm4-bare/arm-none-eabi/include -isystem
>> /home/joe/bin/gcc/arm-cm4-bare/arm-none-eabi/sys-include    -o conftest
>> -g -O2 -g -Os   conftest.c  >&5
>> conftest.c: In function 'main':
>> conftest.c:12:1: sorry, unimplemented: Thumb-1 hard-float VFP ABI
>>
>> I only care about Cortex-M4, which exclusively uses Thumb-2. How can I
>> completely disable Thumb-1 so I can successfully build gcc?
> My equivalent for 4.9.1 had —with-cpu=cortex-m4 (and not —with-tune=cortex-m4)

Yes, --with-tune doesn't specify which architecture level you're
trying to get so GCC probably defaults to something really old that
uses Thumb1 when asked to compile for -mthumb.

>