Handling packages with SSE extensions

[Tom 'spot' Callaway]

On Wed, 2005-08-17 at 12:47 -0500, Quentin Spencer wrote:

> ATLAS doesn't do this. It is based on compile-time optimizations (that 
> make for very long compiles). Because the resulting binaries are 
> hardware dependent, I'm using the Debian package as a starting point 
> because it uses a scheme of "recorded builds" from "average" hardware to 
> produce binaries that are repeatable regardless of hardware and perform 
> reasonably well on a range of hardware. Some additional performance 
> improvement can be obtained if a user rebuilds a custom package for 
> their system. The ATLAS sourceforge site distributes separate binaries 
> for all of the different SIMD extensions, and I don't see this changing. 
> I was hoping to put all the separate extensions in separate packages and 
> have the user install the correct one (or find a way for yum to find the 
> correct one), like is done with the different kernels. This is a very 
> tricky packaging problem, and I welcome any suggestions on how best to 
> deal with it.

Well, I'm not that familiar with ATLAS, but you might be able to resolve
it like this:

Assuming that on i386, it can generate multiple binary files for SSE,
SSE2 and 3Dnow optimizations.

Loop through all possible optimizations, and generate sets of binaries
that are named appropriately (e.g. atlas-sse, atlas-sse2, atlas-3dnow)

Generate a program that detects which optimizations the hardware is
capable of using.

In %files, %ghost the expected binary name. Then, in %post, run the
detection program and use the output to symlink the best optimized fit
to the expected binary name.

The downside to this approach is that you end up with a lot of extra
binaries on the system that can't be used (or perform sub-par). :/

~spot
-- 
Tom "spot" Callaway: Red Hat Senior Sales Engineer || GPG ID: 93054260
Fedora Extras Steering Committee Member (RPM Standards and Practices)
Aurora Linux Project Leader: http://auroralinux.org
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