Re: [gentoo-user] USE="mmx mmxext sse sse2 ssse3 3dnow 3dnowext"

[Volker Armin Hemmann <volkerarmin@googlemail.com>]

On Dienstag 26 Mai 2009, Stroller wrote:
> On 26 May 2009, at 06:10, Volker Armin Hemmann wrote:
> >> ...
> >> The mplayer ebuild is stated to be "intelligent" about ignoring these
> >> flags if necessary, so I'm not sure that "if mplayer works, so will
> >> everything else" is a safe conclusion. My question was exactly if it
> >> was so - are other ebuilds also as "intelligent" as mplayer?
> >>
> >> ...
> >> I'd disagree. If it were really simple, Portage would take care of it
> >> automagically for me. It (apparently?) doesn't.
> >
> > portage does not take care. mplayers build has a cpu feature
> > autodection.
> >
> > Different stuff. Really.
>
> Right, that was the question. Thank you for answering it. Sorry if I
> was unclear.
>
> >> Looks like `echo media-video/mplayer mmx mmxext sse sse2 ssse3 3dnow
> >> 3dnowext >> /etc/portage/package.use` unless someone else is able to
> >> be more informative.
> >
> > yeah, except that is bullshit
>
> So? It doesn't matter. Uh, I mean - that's what you just told me.


see a bit below

>
> > no pentium can do 3dnow.
>
> I did think that. But with other instructions adopted by the other
> manufacturer (eg. Intel adopted the amd64 architecture, I think?) it
> seemed odd that a set of instructions would be ignored so long.

because 3dnow is/was very unimportant for intel- but Intel couldn't compete 
without AMD64. So they had to licence it. 3dnow and SSE have a lot of commands 
in common/similar commands anyway so it doesn't really matter from Intels POV.

The thing is - autodetection is a useflag too - and you are trusting a feature 
that might break any time. Better to know what your cpu can and can't do and 
set it by yourself. Also there are a lot more packages that do benefit from 
mmx, 3dnow, sse...

>
> > Or was there a 3dnow flag in /proc/mtrr? No? Then
> > don't even touch it. Same for ssse3. This has nothing to do with
> > sse3. It is
> > something completly different. And p4 never had this.
>
> That's cool. I'll just keep minimal hardware USE flags in make.conf;
> in /etc/portage/package.use I'll tell mplayer to USE everything
> (including 3dnow) that it can.

sorry that I was harsh. I shouldn't have been awake when I wrote the mail - 
freaking heat...