> > > Why would flags like mmx, mmxext, sse, and sse2 be masked from mplayer
> > > for me?
> > >
> > > /etc/make.profile ->
> > > /usr/portage/profiles/default-linux/amd64/2006.1/desktop
> >
> > I'm not sure why the use flags are masked.
>
> Heh, and then I found it...
>
> http://bugs.gentoo.org/show_bug.cgi?id=104674
>
Several days ago the guys at gentoo-am64 mailing list explained to me
all these flags enable different CFLAGS optimizations which came as the
x86 architecture evolved during the years. When using amd64 the CFLAG
"-march amd64" enables all architecture specific functions in gcc.
Simply gcc knows this CPU supports these instuction sets. Further AMD64
provides sse2 and the latest CPU models even sse3 which are superior to
mmx, 3dnow and the other flags mentioned in this thread. So there is
nothing wrong if these are hard disabled - gcc will take advantage of
the amd64 arch. without these flags beeng enabled.
Also I found this official article in the amd64 project site:
http://www.gentoo.org/doc/en/gentoo-amd64-faq.xml#cflags
"Warning: You should never place -fPIC, -m32 or -m64 in your CFLAGS.
They are automatically added whenever they are needed. Please also note
that the -Os flag is currently not supported."
I'm actually using -march=k8 in accordance with the Gentoo Handbook's
recommendation. Should I be using -march=amd64? I have an AMD
Sempron64 3000+ CPU.
- Grant
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