[MPlayer-users] Mplayer-vaapi fails to compile.

[dE .]

On 10/02/12 18:48, Tom Evans wrote:
> On Tue, Oct 2, 2012 at 1:17 PM, dE .<de.techno at gmail.com>  wrote:
>> As you might have know, Gentoo is a source based distro, and each of it's
>> install (on various PCs) is not designed to be generic; so in Gentoo when we
>> compile source tarballs (portage does this automatically, and that's how I
>> get ffmpeg and mplayer from git), we use non generic flags (-march=native)
>> since the binaries are not intended to be used on a different CPU; for this
>> reason, no use adding AMD specific instructions (3dnow*) with an Intel CPU,
>> or adding newer ssse* instructions for an older CPU.
>>
>> Also, things becomes more complicated when you cross compile (e.g. for ARM
>> boards on an fast x64 processor), which's commonly done by Gentoo users. So
>> it's a good idea to force instructions, cause mplayer auto detects it by
>> default (right?).
> It is almost always wrong to use --enable-foo in mplayer's configure
> script, since this will unconditionally turn on options that normally
> would be tested to see if the feature is supported by your currently
> installed libraries and so on. Simply having a library is not enough,
> you must have the right version, and that is what configure tests.

Yes, and it the version information is included as dependencies in the 
right package. Since it's a source based distro, it makes sense to 
dynamically link with system libraries.

> More specifically on processor flags, if you omitted all of the
> --disable-3dnow --enable-sse flags, mplayer would test itself to see
> what your processor supports and turn on the right flags for your
> processor.

But that results in complications if you're cross compiling.

> This problem comes from Gentoo's build system; each one of those
> options will correspond to a USE flag in Gentoo, and the only thing
> Gentoo can do with a USE flag is to turn on or turn off a configure
> option. Most of them are unnecessary unless you are trying to produce
> a packaged binary for many machines, which is the opposite of what
> Gentoo is trying to do.
>
> Gentoo isn't doing it "right" as far as mplayer is concerned - and you
> will always get a little grief on here debugging with so many non
> standard configure options -  but it is right from Gentoo's point of
> view!

The real problem resides with the fact that if you've not set an USE to 
yes, portage will automatically pass --disable-foo.