On Thu, 18 Jan 2001, Tuukka Toivonen wrote:

> I suppose that if the CPU has MMX, then it's ok to write 1 in PCE
> bit. This should be valid for Intel CPUs, but it's certainly possible that
> there are non-Intel CPUs that have MMX but not RDPMC. However, I'd guess
> that writing 1 to PCE bit doesn't do any harm.

 It's not completely OK to write 1 to cr4.pce as you get a GP fault if a
CPU does not support it.  However, you may handle the exception yourself
and enable rdpmc unconditionally, i.e. with no feature test (Intel states
cr4.pce is model-specific anyway) -- hopefully no vendor overloads the
cr4.pce bit.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +

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