Cannot build GCC for Cortex-M0

[Andriy Sukhynyuk]

Hi Kai,

>> Well I spent yesterday and could not find how to do it. It all ends up in 
>error
>> trying to compile test file with -march=armv6-m but without -mthumb.


>Please describe 'compile'... Producing the assembly source and even
>the object file should succeed but linking the object with a Thumb-only
>C library of course would lead into troubles. Tests with my similar
>GCC on Linux built by pure curiosity :
When I try to compile C-source file with Code Red LPCXpresso which is shipped 
with GCC 4.3.3 with -mcpu=cortex-m0 but without -mthumb 


arm-none-eabi-gcc  -I"YYYY" -O0 -g3 -Wall -c -fmessage-length=0 -fno-builtin 
-ffunction-sections -mcpu=cortex-m0  -MMD -MP -MF"src/XXXX.d" -MT"src/XXXX.d" 
-o"src/XXXX.o" "../src/XXXX.c"

I get the message:

../src/XXXX.c:1: error: target CPU does not support ARM mode
make: *** [src/XXXX.o] Error 1

I am pretty sure that it is a compile time error. Adding, or rather restoring 
since, option -mthumb results in successful production of object file.

It is also true that when we build toolchain with --with-mode=thumb then 
excluding -mthumb does not make compile process fail.

Returning back to building toolchain with multilib enabled and default mode  
--with-mode=arm, I made the following changes to 
\gcc-4.5.0\gcc\config\arm\t-arm-elf file 


+MULTILIB_OPTIONS      += march=armv6-m mthumb
+MULTILIB_DIRNAMES     += thumb\/armv6-m

+MULTILIB_EXCEPTIONS   += *marm*/*march=armv6-m*

+MULTILIB_OPTIONS    += mno-thumb-interwork/mthumb-interwork
+MULTILIB_DIRNAMES   += normal interwork
+MULTILIB_EXCEPTIONS += *mthumb-interwork*/*march=armv6-m*  

I would like to think that  *marm*/*march=armv6-m* forbids building ARM library 
when -marmv6-m is present but it does not! 


The last lines of the  `config.log' are (sorry for pasting here so much text):
------------------------------------------------------------------------------------------------------------------------------------

configure:3004: $? = 0
configure:2993: /f/asu/Cortex/gcc-4.5.0/build4/./gcc/xgcc 
-B/f/asu/Cortex/gcc-4.5.0/build4/./gcc/ -B/f/cross-gcc/4.5.0/arm-none-eabi/bin/ 
-B/f/cross-gcc/4.5.0/arm-none-eabi/lib/ -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/include -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/sys-include  -march=armv6-m -v >&5
Reading specs from f:/asu/Cortex/gcc-4.5.0/build4/gcc/specs
COLLECT_GCC=f:\asu\Cortex\gcc-4.5.0\build4\gcc\xgcc.exe
COLLECT_LTO_WRAPPER=f:/asu/Cortex/gcc-4.5.0/build4/gcc/lto-wrapper.exe
Target: arm-none-eabi
Configured with: ../gcc-4.5.0/configure --target=arm-none-eabi 
--build=i686-pc-mingw32 --host=i686-pc-mingw32 --prefix=/f/cross-gcc/4.5.0 
--disable-nls --disable-shared --disable-threads --with-gnu-gcc --with-gnu-ld 
--with-gnu-as --with-dwarf2 --enable-languages=c --enable-interwork 
--enable-multilib --with-gmp=/f/cross-gcc/4.5.0 --with-mpfr=/f/cross-gcc/4.5.0 
--with-mpc=/f/cross-gcc/4.5.0 --with-newlib 
--with-headers=../../newlib-1.18.0/newlib-1.18.0/newlib/libc/include 
--disable-libssp --disable-libstdcxx-pch --disable-libmudflap --disable-libgomp 
-v
Thread model: single
gcc version 4.5.0 (GCC) 
configure:3004: $? = 0
configure:2993: /f/asu/Cortex/gcc-4.5.0/build4/./gcc/xgcc 
-B/f/asu/Cortex/gcc-4.5.0/build4/./gcc/ -B/f/cross-gcc/4.5.0/arm-none-eabi/bin/ 
-B/f/cross-gcc/4.5.0/arm-none-eabi/lib/ -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/include -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/sys-include  -march=armv6-m -V >&5
xgcc.exe: '-V' must come at the start of the command line
configure:3004: $? = 1
configure:2993: /f/asu/Cortex/gcc-4.5.0/build4/./gcc/xgcc 
-B/f/asu/Cortex/gcc-4.5.0/build4/./gcc/ -B/f/cross-gcc/4.5.0/arm-none-eabi/bin/ 
-B/f/cross-gcc/4.5.0/arm-none-eabi/lib/ -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/include -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/sys-include  -march=armv6-m -qversion >&5
xgcc.exe: unrecognized option '-qversion'
xgcc.exe: no input files
configure:3004: $? = 1
configure:3020: /f/asu/Cortex/gcc-4.5.0/build4/./gcc/xgcc 
-B/f/asu/Cortex/gcc-4.5.0/build4/./gcc/ -B/f/cross-gcc/4.5.0/arm-none-eabi/bin/ 
-B/f/cross-gcc/4.5.0/arm-none-eabi/lib/ -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/include -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/sys-include  -march=armv6-m -o conftest -g 
-O2   conftest.c  >&5
conftest.c:1:0: error: target CPU does not support ARM mode
configure:3023: $? = 1
configure:3211: checking for suffix of object files
configure:3233: /f/asu/Cortex/gcc-4.5.0/build4/./gcc/xgcc 
-B/f/asu/Cortex/gcc-4.5.0/build4/./gcc/ -B/f/cross-gcc/4.5.0/arm-none-eabi/bin/ 
-B/f/cross-gcc/4.5.0/arm-none-eabi/lib/ -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/include -isystem 
/f/cross-gcc/4.5.0/arm-none-eabi/sys-include  -march=armv6-m -c -g -O2  
conftest.c >&5
conftest.c:1:0: error: target CPU does not support ARM mode
configure:3237: $? = 1
configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME "GNU C Runtime Library"
| #define PACKAGE_TARNAME "libgcc"
| #define PACKAGE_VERSION "1.0"
| #define PACKAGE_STRING "GNU C Runtime Library 1.0"
| #define PACKAGE_BUGREPORT ""
| #define PACKAGE_URL "http://www.gnu.org/software/libgcc/"
| /* end confdefs.h.  */
| 
| int
| main ()
| {
| 
|   ;
|   return 0;
| }
configure:3251: error: in 
`/f/asu/Cortex/gcc-4.5.0/build4/arm-none-eabi/thumb/armv6-m/libgcc':
configure:3254: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details.