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Date: Thu, 05 Dec 2013 16:18:11 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [Bug 1257099] [NEW] QEMU fails to build on CentOS
 5.10 with relocation R_X86_64_PC32 error
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To: Don Slutz <dslutz@verizon.com>
Cc: 1257099@bugs.launchpad.net, Ian Campbell <Ian.Campbell@citrix.com>, xen-devel@lists.xensource.com, qemu-devel@nongnu.org, Stefano Stabellini <stefano.stabellini@eu.citrix.com>

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