[FFmpeg-devel] Fix Altivec detection on Linux.

Reimar Döffinger Reimar.Doeffinger
Thu Mar 20 13:08:06 CET 2008

On Thu, Mar 20, 2008 at 11:52:26AM +0000, David Woodhouse wrote:
> On Thu, 2008-03-20 at 12:24 +0100, Reimar D?ffinger wrote:
> > In my personal opinion the "right" solution is to choose one single way
> > of detecting AltiVec, and tell anyone where it does not work to fix
> > their OS. 
> That's what we've done, isn't it? We've put it in the AT_HWCAP field of
> the ELF auxiliary vector, which is passed to every program as it's
> started up and contains all kinds of interesting information about the
> system such as cache line sizes, etc. That's the _right_ place for it.
> However, glibc makes it hard for a library to get at the auxvec, so the
> easiest way to get it is to open /proc/$$/auxv and read it. I'm really
> not feeling quixotic enough this week to argue with Uli about that.

Well, then it should be even easier to implement support for this for
other OSes, and then remove the other methods if we have any (e.g. at least
MPlayer currently uses an ioctl on OSX)?

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