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Bug 523942 - media-video/ffmpeg - remove CFLAGS override for -march=native
Summary: media-video/ffmpeg - remove CFLAGS override for -march=native
Status: RESOLVED WONTFIX
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Media-video project
URL:
Whiteboard:
Keywords: PATCH
Depends on:
Blocks:
 
Reported: 2014-09-28 13:15 UTC by Sebastian
Modified: 2014-10-05 10:42 UTC (History)
0 users

See Also:
Package list:
Runtime testing required: ---


Attachments
ffmpeg-no-cflags-override.patch (ffmpeg-no-cflags-override.patch,8.11 KB, patch)
2014-09-28 13:16 UTC, Sebastian
Details | Diff

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Description Sebastian 2014-09-28 13:15:28 UTC
Hello,

Please consider removing the lines from the ebuilds that replace "native" with "host". They stem from bugs 172723 and 273421, from the year 2007 and 2009 respectively.

Now - many years later - ffmpeg compiles fine with -march=native. I don't see why these lines would still be warranted.

I had requested the same for libav earlier, and it was committed, see bug 458768.

Reproducible: Always
Comment 1 Sebastian 2014-09-28 13:16:30 UTC
Created attachment 385672 [details, diff]
ffmpeg-no-cflags-override.patch

Patch to remove the override from the current ebuilds.
Comment 2 Alexis Ballier gentoo-dev 2014-10-05 06:24:23 UTC
this patch is just as wrong for libav as it is for ffmpeg

ffmpeg uses the cpu fed at configure to determine which hand written asm is better to use: have a look at configure. you should really diff the output of configure with and without this on x86; for example, here is disables 'fast_cmov'.

plus, it helps for cross-compile optimizations.
Comment 3 Sebastian 2014-10-05 10:42:11 UTC
Hello Alexis,

Thanks for pointing this out. I reopened the old bug to get the change reverted.

Kind regards,
Sebastian