[FFmpeg-devel] [PATCH]Remove test for cpuid instruction from cpuid.c

Måns Rullgård mans
Sun Nov 23 17:02:43 CET 2008

Carl Eugen Hoyos <cehoyos at ag.or.at> writes:

> M?ns Rullg?rd <mans <at> mansr.com> writes:
>> Reimar D?ffinger <Reimar.Doeffinger <at> stud.uni-karlsruhe.de> writes:
>> > On Sun, Nov 23, 2008 at 01:45:07PM +0000, Carl Eugen Hoyos wrote:
>> >> I will copy the assembly sources into issue 709: It would be nice
>> >> if somebody who actually understands the code could comment there.
>> >
>> > Please replace pushf/popf by pushfd/popfd.
> /tmp/cc3SAE8s.s: Assembler messages:
> /tmp/cc3SAE8s.s:10: Error: no such instruction: `pushfd'
> /tmp/cc3SAE8s.s:15: Error: no such instruction: `popfd'
> /tmp/cc3SAE8s.s:16: Error: no such instruction: `pushfd'

Huh?  That mnemonic *is* in the manuals.

>> Can someone please explain how the same opcode can behave differently
>> depending on the assembler mnemonic used?
> Unfortunately, I can't.
> But one of you can probably tell me how we can save the stack pointer
> independently of what the compiler does?

That's only half the problem.  The bit we're messing with is in the
upper 16 bits of the flags, so the 16-bit pushf/popf won't notice it.

M?ns Rullg?rd
mans at mansr.com

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