[FFmpeg-devel] [PATCH] Fix configure to disable MMX for Pentium Pro

[Alex Converse]

2010/8/26 M?ns Rullg?rd <mans at mansr.com>:
> Alex Converse <alex.converse at gmail.com> writes:
>
>> 2010/8/26 M?ns Rullg?rd <mans at mansr.com>:
>>> Janne Grunau <janne-ffmpeg at jannau.net> writes:
>>>
>>>> On Thu, Aug 26, 2010 at 01:52:22AM -0400, Jason Garrett-Glaser wrote:
>>>>> On Thu, Aug 26, 2010 at 12:44 AM, Eli Friedman <eli.friedman at gmail.com> wrote:
>>>>> > Attached. ?This is essentially fixing an oversight in r21277.
>>>>> >
>>>>> > -Eli
>>>>>
>>>>> This means every distro who uses --cpu=i686 or similar will silently
>>>>> have their ffmpeg crippled the next time they make a build.
>>>>>
>>>>> I would rather roll back r21277 than apply this patch.
>>>>
>>>> What about requriring --enable-runtime-cpudetect for i686 with mmx and
>>>> crippling emms() in that case like attached patch?
>>>
>>> I'm not changing a thing until someone shows me evidence of ffmpeg
>>> actually being used on such CPUs.
>>
>> We shouldn't claim to support something that doesn't work.
>
> But we _do_ support them. ?Disable mmx and it will run on a 486 even.
>

./configure --cpu=prentiumpro says build me an FFmpeg for a
PentiumPro. The result will no longer run on a PentiumPro.

That is broken behavior. It doesn't matter that the chip is old.