[coreboot] [v2] r4745 - in trunk/coreboot-v2/src/cpu/intel: socket_PGA370 socket_mPGA479M socket_mPGA604

Peter Stuge peter at stuge.se
Fri Oct 9 06:45:36 CEST 2009

ron minnich wrote:
> > Isn't MMX or SSE something attached to a given CPU rather than a
> > socket?
> The current design sets the choice of mmx/sse in the *mainboard* by
> the inclusion of .inc files.
> Moving it to the socket is a bit better than that.

Very much!

> If a socket includes multiple CPU types, is there ever a case where
> different CPUs for that socket have different settings for MMX and
> SSE?

Yes. It's true for all Pentium {,II,III} sockets.

> It gets worse! For a given socket, you have to use the *least* set
> of capabilities.
> I hope this makes sense, I'm tired.

It does. I acked specifically because of this situation with sockets
that can have CPUs with differing features. You added the selects
only to the sockets one notch "above", so that the feature is
guaranteed to be available. That's the good way.

> Bottom line, however: the socket determines usage of SSE and MMX,
> not the CPU, because at the socket level you know which CPU types
> to support, but at the CPU level you don't.

At the CPU level there is just one CPU to support. But unless
mainboards specify a CPU rather than a socket that doesn't matter.

However, if boards usually specify sockets (makes more sense, right)
then the register option really must be controlled by sockets.

Stefan got me thinking that maybe a particular board would be limited
to a single CPU - but that's not how it works, right?


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