FP save/restore code in ppc32/ppc64 kernels

Peter Bergner bergner at borg.umn.edu
Tue Aug 13 00:34:30 EST 2002


Paul Mackerras wrote:
:> It might be a good idea to clear the fpscr after saving it out to
:> the thread struct though...
:
: Exactly.  We don't.  If we did then we could do as you say and it
: would work on SMP.  We could do that as long as we are sure we won't
: ever want to do a UP kernel on ppc64...

Or we could force the UP kernel to act like the SMP kernel and not
use lazy save.  How big of a "win" is lazy save on UP kernels?
I will also note that UP kernels haven't worked for nearly 2 years
on PPC64.

Peter

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