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

[Don Slutz <dslutz@verizon.com>]

On 12/05/13 10:18, Paolo Bonzini wrote:
> Il 04/12/2013 02:32, Don Slutz ha scritto:
>> Any hints or pointers about the bug in RHEL5 binutils?  I can try and
>> make a patch to auto detect this.
> Actually it's RHEL5 GCC:
>
> $ cat f.c
> void *
> f(unsigned char *buf, int len)
> {
>      return (void*)0L;
> }
>
>
> void *
> g(unsigned char *buf, int len)
> {
>      return f(buf, len);
> }
> $ 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
>
> On RHEL5:
> $ gcc -S -o - f.c -fPIE -fPIC |grep call
> 	call	f
>
> On RHEL6:
> $ gcc -S -o - f.c -fPIE -fPIC |grep call
> 	call	f@PLT
>
> Paolo
RHEL5 also "works" if you add -pie:

dcs-xen-53:~/tmp>gcc -shared -o f.so f.c -fPIE -fPIC
/usr/bin/ld: /tmp/cc6pp1n2.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>gcc -shared -o f.so f.c -fPIE -fPIC -pie
dcs-xen-53:~/tmp>gcc -S -o - f.c -fPIE -pie|grep call
         call    f

I have not figured out a way to take advantage of this.

I just checked and Fedora 17 has the same issue with gcc:
FC17:
dcs-xen-52:~/tmp>gcc -S -o - f.c -fPIE -fPIC |grep call
         call    f
dcs-xen-52:~/tmp>gcc -shared -o f.so f.c -fPIE -fPIC
/usr/bin/ld: /tmp/ccUlVgMP.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

However QEMU builds just fine.  So it is looking like libtool is also 
part of the problem.

    -Don Slutz