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SubjectRe: [PATCH v13 8/9] Add 32 bit VDSO time support for 32 bit kernel
> EBX is a reserved as the base register when compiling with -fPIC.
> Otherwise it get a "error: can't find a register in class 'BREG' while
> reloading 'asm'".

In this case you have to dwarf annotate the push/pop

>
> > Also I if this calls syscall.S:__kernel_vsyscall it clobbers more registers
> > (ecx at least?) and you need to describe that to gcc with a +
>
> Sine ECX is in use as the second parameter it is still marked as
> clobbered.

No input parameters are not clobbered.

> I think it should word... As i know a system call will preserve all
> register expect the EAX, which is marked as in and out for this asm()
> directive.

Yes the syscall does, but the vsyscall stub does not (for the !0x80 case)

> This is due the -m32 compilation, i will get a log of
> "warning: integer constant is too large for 'unsigned long' type",
> because a unsigned long is only 32 bit.

Don't explain it to me, put it into a comment.

-Andi

--
ak@linux.intel.com -- Speaking for myself only


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