Re: [mpeg2-dev] mmxext acceleration

[Michel L. <wa...@zo...>]

On Sat, Nov 28, 2009 at 03:58:00PM +0100, Gour wrote:
> The solution to this particular problem is to fix the following bug in
> libmpeg2:
> 
> >#if defined(ARCH_X86) || defined(ARCH_X86_64)
> >static inline uint32_t arch_accel (uint32_t accel)
> >{  
> [...]
> >    if (accel & (MPEG2_ACCEL_X86_SSE2 | MPEG2_ACCEL_X86_SSE3))
> >	accel |= MPEG2_ACCEL_X86_MMXEXT;  
> 
> "MMXEXT" should be changed to "MMX" here (or the clause should be deleted
> entirely if the MMX flag is not needed in SSE environments).
> </quote>

* Does your crash go away if you clear the MPEG2_ACCEL_X86_MMXEXT flag ?
* Do you know what CPU instruction the crash happens on ?

In libmpeg2, MMXEXT indicates the availability of pshufw and
pavgb instructions. My understanding is that CPUs advertising the
SSE capability must support these instructions.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.