Re: [Xen-devel] [Qemu-devel] [Bug 1257099] [NEW] QEMU fails to build on CentOS 5.10 with relocation R_X86_64_PC32 error

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 12/09/13 08:22, Paolo Bonzini wrote:

Il 09/12/2013 13:47, Don Slutz ha scritto:

On 12/05/13 22:20, Don Slutz wrote:

On 12/05/13 16:24, Richard Henderson wrote:

On 12/06/2013 04:18 AM, Paolo Bonzini wrote:

$ gcc -shared -o f.so f.c -fPIE -fPIC
/usr/bin/ld: /tmp/ccQc9els.o: relocation R_X86_64_PC32 against `f'
can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status


The bug is simply that "-fPIE -fPIC" counts as -fPIE rather than -fPIC:

$ gcc -S -o - f.c -fPIE |grep call
    call    f                      # PC32 relocation
$ gcc -S -o - f.c -fPIC |grep call
    call    f@PLT                  # PLT32 relocation

The easy workaround is to drop -fPIE when we're adding -fPIC.


r~

[snip]

Attached is a much better version.  It drops -fPIE and adds -fPIC for
libtool.

It's not much better, because using position-independent code for shared
libraries is really platform-dependent knowledge of the kind that
libtool is supposed to hide.

For example, on Mac OS X everything is position-independent by default.
 And on some platforms you have -fpic instead of -fPIC.

So I prefer the patch you had that disabled libtool if the platform is
buggy.

Paolo

Well, the detection code is too simple:

FC17 system:

dcs-xen-52:~/tmp/libtool>uname -a
Linux dcs-xen-52 3.8.11-100.fc17.x86_64 #1 SMP Wed May 1 19:31:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
dcs-xen-52:~/tmp/libtool>gcc -shared -fPIE -DPIE f.c  -fPIC -DPIC -o f.so
/usr/bin/ld: /tmp/ccl4By1r.o: relocation R_X86_64_PC32 against symbol `f' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: error: ld returned 1 exit status
dcs-xen-52:~/tmp/libtool>libtool --mode=compile gcc -g -c -fPIE -DPIE f.c
libtool: compile:  gcc -g -c -DPIE f.c  -fPIC -DPIC -o .libs/f.o
libtool: compile:  gcc -g -c -DPIE f.c -fPIE -o f.o >/dev/null 2>&1
dcs-xen-52:~/tmp/libtool>libtool --mode=link gcc -g -o libf.la f.lo -rpath /usr/local/lib
libtool: link: gcc -shared  -fPIC -DPIC  .libs/f.o      -Wl,-soname -Wl,libf.so.0 -o .libs/libf.so.0.0.0
libtool: link: (cd ".libs" && rm -f "libf.so.0" && ln -s "libf.so.0.0.0" "libf.so.0")
libtool: link: (cd ".libs" && rm -f "libf.so" && ln -s "libf.so.0.0.0" "libf.so")
libtool: link: ar cru .libs/libf.a  f.o
libtool: link: ranlib .libs/libf.a
libtool: link: ( cd ".libs" && rm -f "libf.la" && ln -s "../libf.la" "libf.la" )

CentOS 5.10:

dcs-xen-53:~/tmp/libtool>uname -a
Linux dcs-xen-53 2.6.18-371.el5xen #1 SMP Tue Oct 1 09:15:30 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux
dcs-xen-53:~/tmp/libtool>gcc -shared -fPIE -DPIE f.c  -fPIC -DPIC -o f.so
/usr/bin/ld: /tmp/ccAy1vZK.o: relocation R_X86_64_PC32 against `f' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status
dcs-xen-53:~/tmp/libtool>libtool --mode=compile gcc -g -c -fPIE -DPIE f.c
mkdir .libs
 gcc -g -c -fPIE -DPIE f.c  -fPIC -DPIC -o .libs/f.o
 gcc -g -c -fPIE -DPIE f.c -o f.o >/dev/null 2>&1
dcs-xen-53:~/tmp/libtool>libtool --mode=link gcc -g -o libf.la f.lo -rpath /usr/local/lib
gcc -shared  .libs/f.o   -Wl,-soname -Wl,libf.so.0 -o .libs/libf.so.0.0.0
/usr/bin/ld: .libs/f.o: relocation R_X86_64_PC32 against `f' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status

I have attached a patch that uses libtool to determine if gcc & libtool is broken.
     -Don

Attachment: 0001-configure-Disable-libtool-if-fPIE-does-not-work-with.patch
Description: Text Data

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