Re: fpu IO port reservation (arch/i386)

From: Maciej W. Rozycki
Date: Mon Sep 24 2007 - 07:42:37 EST

On Fri, 21 Sep 2007, Andi Kleen wrote:

> > For the curious the details of all the hassle are reasonably well
> > described in the Intel's AP-578 application note.
> Thanks. Ok it has to stay for for i386 then; although it would be in theory
> possible to only reserve when the CPU is a real 386. For x86-64 it's
> gone now.

For anything newer the latch is still there in the chipset; most likely
in the south bridge and probably actively decoded (irrespective of the
architecture of the bit behind the north bridge) though it may be possible
to disable it in a chip-specific manner. If there is no south bridge in a
given system, then it is probably safe not to claim the port.

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