[flac-dev] Lets do a 1.3.2 release

Dave Yeo dave.r.yeo at gmail.com
Tue Jan 19 14:33:35 PST 2016


On 01/19/16 01:04 PM, lvqcl wrote:
> Dave Yeo wrote:
>
>>> I cannot find information what version of binutils supports AVX/AVX2/FMA
>>> instructions, but IIRC OS/2 doesn't support AVX instructions anyway,
>>> so it doesn't matter much.
>>
>> Surprisingly, I've yet to have a report of an AVX related crash or trap
>> (used in FFmpeg and projects based on it, Mozilla, probably others).
>> As I understand it, support is a matter of saving the extended registers
>> during a context switch and perhaps our kernel had some future proofing
>> added towards the end.
>
> WinXP/Vista also don't support AVX but ffmpeg doesn't crash there.
>
> IIRC, OS must explicitely enable AVX support, and an application must check
> whether the OS supports AVX or not.

OK, that makes sense and after looking quickly at Agners 
optimizing_assembly.pdf I can see how FFmpeg does it though I still find 
it hard to follow the code in flac.
The second version of the patch is to be preferred.
I'll have to ask the Russians about their alternative kernel (OS/4)
Dave


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