Jakub's Recommendations for ia32 Support

Wed Feb 4 00:56:16 UTC 2009

On Wednesday, 04 February 2009 at 01:34, Callum Lerwick wrote:
> On Tue, 2009-02-03 at 19:53 +0100, Dominik 'Rathann' Mierzejewski wrote:
> > >  i686 to i686 w/ SSE2 would be a performance win, but that is
> > > clearly not an option for Fedora.
> > 
> > SSE2-optimized libraries can be built and installed into /usr/lib/sse2.
> > Our ld.so already supports that.
> 
> Why does SSE2 get this treatment, and not SSE? I've found SSE much more
> useful, and more common. SSE2 pretty much means P4 only on i386, Athlons
> didn't get SSE2 until the Athlon 64 and those should be running x86-64
> anyway. Whereas there's a lot of Pentium 3s and Athlon XPs with SSE out
> there.

I was wondering about the same thing. There's little to no documentation
on this subject so I had to dig into glibc sources to see how it works.
Apparently, glibc distinguishes some "features" for CPUs and those that
are "major" can have separate directories with optimized libraries.
In Fedora, "major" features are "i686" and "sse2". Whereas in Debian,
it's just "cmov", apparently.

Can anyone shed more light here? Jakub?

Regards,
R.

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