Re: [LTP] Building LTP in a 64-bit machine for 32-bit target

[<sha...@gm...>]

Sedat Dilek <sedat.dilek@...> writes:

> 
> On Thu, Mar 7, 2013 at 9:51 AM, Shashi <shashi859@...> wrote:
> > Pedro Fonseca <pfonseca@...> writes:
> >
> >>
> >> Hi,
> >>
> >> I've been trying to cross compile LTP on a 64-bit x86 machine to produce
> >> tests for a 32-bit x86 machines. Unfortunately, so far I haven't found a
> >> clean way of achieving this.
> >>
> >> I've tried configuring with "./configure --host=i386" but this still
> >> produces x86-64 binaries.
> >>
> >> I've also tried configuring with "CFLAGS=-m32 ./configure CFLAGS=-m32"
> >> but it gives compilation errors on some tests (e.g.
> >> testcases/kernel/syscalls/chown01_16). I can get past some of the errors
> >> by disabling the "/../utils/compat_16.mk" lines in the individual test
> >> Makefiles. But is there a better way to compile LTP for 32-bit on a 64-bit?
> >>
> >> Thanks,
> >> Pedro
> >>
> >> ------------------------------------------------------------------------------
> >> Everyone hates slow websites. So do we.
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> >>
> >
> > Hello Pedra Fonseca,
> >
> > ./configure --build=i686-pc-linux-gnu --target=i686-pc-linux-gnu "CFLAGS=-m32"
> > "CPPFLAGS=-m32" "LDFLAGS=-m32"
> >
> > I use the above command to build ltp for 32-bit architecture on 64-bit machine.
> > Once you do run this, you can check the CFLAGS, CPPFLAGS, LDFALGS being set in
> > config.status file. --target flag is to set target environment if it is
> > different from build environment.
> >
http://stackoverflow.com/questions/5139403/whats-the-difference-of-configure-option-build-host-and-target
> >
> > In fedora-64 bit, to build a 32-bit binary you need following packages
> > sudo yum install glibc-devel.i686 libgcc.i686
> >
> > May be in Ubuntu, you may need these packages or similar kind. If not installed
> > gcc will throw some error. Let me know if you still find problem.
> >
> > Regards,
> > ShashiKiran
> >
> 
> [ CC Pedro ]
> 
> AFAICS "-m32" is available on gcc, dunno if for example clang supports
> that, too.
> 
> Can't say if "-m32" as LDFLAGS makes any sense or to say IOW "-m32"
> for CC is sufficient.
> Maybe you can explain that, Shashi?
> 
> To support "-m32" CFLAGS for gcc on Debian/Ubuntu you need to install
> 'gcc-multilib' (gcc with biarch-support) package.
> This installs 'libc6-i386' and 'libc6-i386-dev' packages automatically.
> 
>      $ sudo apt-get update
>      $ sudo apt-get install gcc-multilib
> 
> Another way could be to install multiarch-support if not available
> (binutils-mutiarch and multiarch-support packages).
> But I should check Debian's/Ubuntu's wiki pages, again... how to build
> on amd64 for i386...
> 
> Hope this helps people reading this ML.
> 
> Regards,
> - Sedat -
> 
> >
> >
> >
> > ------------------------------------------------------------------------------
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> > _______________________________________________
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> > Ltp-list@...
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> 
> ------------------------------------------------------------------------------
> Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester  
> Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the  
> endpoint security space. For insight on selecting the right partner to 
> tackle endpoint security challenges, access the full report. 
> http://p.sf.net/sfu/symantec-dev2dev
> 

Hi Sedat Dilek,

If LDFLAGS=-m32 is not set, then following error is observed while building ltp-pan,

      gcc -m32 -g -O2 -fno-strict-aliasing -pipe -Wall -m32 -Wno-error -I/home/user/ltp/ltp-full-20120903/pan -I../include -I../include -c -o ltp-bump.o ltp-bump.c
      gcc -m32 -g -O2 -fno-strict-aliasing -pipe -Wall -m32 -Wno-error -I/home/user/ltp/ltp-full-20120903/pan -I../include -I../include  -c -o zoolib.o zoolib.c
      gcc -L../lib  ltp-bump.o zoolib.o   -lm  -o ltp-bump 
 
     /usr/bin/ld: i386 architecture of input file `ltp-bump.o' is incompatible with i386:x86-64 output
      /usr/bin/ld: i386 architecture of input file `zoolib.o' is incompatible with i386:x86-64 output
      collect2: ld returned 1 exit status
      make: *** [ltp-bump] Error 1

I feel that, as per rules set by makefile, gcc trying to build 64bit binary using 32bit objects. So When LDFLAGS is set to "-m32", gcc will create create 32bit binary by linking to 32bit object files.

      gcc -m32  -L../lib  ltp-bump.o zoolib.o   -lm  -o ltp-bump 
      gcc -m32 -g -O2 -fno-strict-aliasing -pipe -Wall -m32 -Wno-error -I/home/user/ltp/ltp-full-20120903/pan -I../include -I../include -c -o ltp-pan.o ltp-pan.c
      gcc -m32 -g -O2 -fno-strict-aliasing -pipe -Wall -m32 -Wno-error -I/home<br/><br/><div style='width:300px;border-top:1px solid #d2d2d2;'></div><br/><a href='http://www.way2sms.com' style='color:#7b7b7b;text-decoration: none;'>Mail sent via way2sms.</a>