From: Markus Gutschke <markus@google.com>

Gcc reserves %ebx when compiling position-independent-code on i386. This 
means, the _syscallX() macros in include/asm-i386/unistd.h will not 
compile. This patch is against 2.6.15.6 and changes the existing macros 
to take special care to preserve %ebx.

The bug can be tracked at http://bugzilla.kernel.org/show_bug.cgi?id=6204

Signed-off-by: Markus Gutschke <markus@google.com>

---

Andrew Morton wrote:
> Markus Gutschke <markus@google.com> wrote:
>>That is certainly possible. The new macros work in both modes, but they 
>>are slightly less efficient than the old macros, if you have access to 
>>%ebx (i.e. in non-PIC code). If you prefer, we could just remove the old 
>>macros and unconditionally replace them with the new ones. 
> 
> I'd be OK with that - the kernel doesn't (shouldn't) care about the
> performance of __KERNEL_SYSCALLS__ stuff.  I doubt if glibc is borrowing
> the kernel's macros.

Would you like this patch better? It now unconditionally replaces the 
old macros with a fixed version. This will entail a minor performance 
penalty in non-PIC mode. But for the vast majority of applications the 
difference should be entire negligible.

Once this change has made it into the kernel, I will try to get it 
propagated into libc.


Markus