cross compiling gcc for i686 target

[vijay nag]

I tried to build with host,build = amd64-pc-linux-gnu and
target=i686-pc-linux-gnu.  Binutils compile successfully for
i686-pc-linux-gnu target , but when native compiler tries to invoke
"i686-pc-linux-gn-as" which by default emits 32 bit code i see the
following errors.

gcc -c   -g -O2 -DIN_GCC -DCROSS_DIRECTORY_STRUCTURE  -W -Wall
-Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes
-Wmissing-format-attribute -Wold-style-definition -Wc++-compat
-DHAVE_CONFIG_H -DGENERATOR_FILE -I. -Ibuild -I../../../gcc/gcc
-I../../../gcc/gcc/build -I../../../gcc/gcc/../include
-I../../../gcc/gcc/../libcpp/include
-I/localdisk/vinag/tmp/sbtools.tmp.201302221200/sbtools/systemsw/tools/src/objdir_201302221200_linux-x86/gcc_stage1/./gmp
-I/localdisk/vinag/tmp/sbtools.tmp.201302221200/sbtools/systemsw/tools/src/gcc/gmp
-I/localdisk/vinag/tmp/sbtools.tmp.201302221200/sbtools/systemsw/tools/src/objdir_201302221200_linux-x86/gcc_stage1/./mpfr
-I/localdiskvinag/tmp/sbtools.tmp.201302221200/sbtools/systemsw/tools/src/gcc/mpfr
-I/localdisk/vinag/tmp/sbtools.tmp.201302221200/sbtools/systemsw/tools/src/gcc/mpc/src
 -I../../../gcc/gcc/../libdecnumber
-I../../../gcc/gcc/../libdecnumber/bid -I../libdecnumber    \
                -DBASEVER="\"4.7.2\"" -DDATESTAMP="\"\"" \
                -DREVISION="\"\"" \
                -DDEVPHASE="\"\"" -DPKGVERSION="\"(GCC) \"" \
                -DBUGURL="\"<http://gcc.gnu.org/bugs.html>\"" -o
build/version.o ../../../gcc/gcc/version.c
/tmp/ccAlfevC.s: Assembler messages:
/tmp/ccAlfevC.s:37: Error: cannot represent relocation type BFD_RELOC_64
/tmp/ccAlfevC.s:38: Error: cannot represent relocation type BFD_RELOC_64
/tmp/ccAlfevC.s:66: Error: cannot represent relocation type BFD_RELOC_64
/tmp/ccAlfevC.s:84: Error: cannot represent relocation type BFD_RELOC_64
/tmp/ccAlfevC.s:102: Error: cannot represent relocation type BFD_RELOC_64
make[2]: *** [build/version.o] Error 1
make[2]: *** Waiting for unfinished jobs....
/bin/sh ../../../gcc/gcc/../move-if-change tmp-optionlist optionlist
echo timestamp > s-options
make[2]: *** wait: No child processes.  Stop.
make[1]: *** [all-gcc] Error 2

exporting CFLAGS='-m64'  I could go past this point. It bails out in
the next stage of compilation when the target compiler is used with
-m64 option with the error "cc1plus: sorry, unimplemented: 64-bit mode
not compiled in"

On Fri, Mar 1, 2013 at 11:58 PM, Ian Lance Taylor <iant@google.com> wrote:
> On Fri, Mar 1, 2013 at 9:39 AM, vijay nag <vijunag@gmail.com> wrote:
>>
>> Is it possible to do a cross compile of gcc-4.7.2 on AMD x86_64 to
>> produce i686 target ?
>>
>> My build, host and target parameters are amd64-pc-linux-gnu,
>> amd64-pc-linux-gnu and i686-pc-linux-gnu. My native compiler again is
>> a 64 bit compiler emitting default 64 bit object code.
>
> Yes, it is possible.
>
> It is also usually unnecessary.  A typical x86_64 compiler
> installation will produce 32-bit x86 code with the -m32 option.
>
> Ian