Messages in this thread | | | Date | Fri, 22 May 1998 06:04:33 -0400 (EDT) | From | "C. Scott Ananian" <> | Subject | Re: Cyrix 6x86MX and Centaur C6 CPUs in 2.1.102 |
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On Fri, 22 May 1998 R.E.Wolff@BitWizard.nl (Rogier Wolff) wrote:
> James Mastros wrote: > > Then again, > > if it deviates from the Intel chips on an undefined matter, or goes above > > and beyond the call of duty, then the chip is better then the Intel > > "equivlent" in that respect, and we should take advantage of those features > > as best as we can. > > In this case, I think Cyrix did the right thing. They added a feature, > (powerdown the CPU as much as possible when not doing anything else). > Now they found out that the Intel specs (indirectly) say the TSC needs > to keep running. So... they made their feature an option. If your OS > isn't prepared to take the consequenses of the added feature, don't > turn it on. Simple.
I hate to have to keep bringing this up: the Cyrix problem is not an 'added feature.' They destroy the top 32-bits of the TSC on HLT. We're not talking about "the TSC stops when the processor clock stops" which is entirely valid (although also problematic for the kernel---this is another issue entirely). To their credit, it appears that you can disable this behaviour. But there's no good reason for destroying register contents; I find it very hard to call this a 'feature'. --Scott @ @ =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-oOO-(_)-OOo-=-=-=-=-= C. Scott Ananian: cananian@lcs.mit.edu / Declare the Truth boldly and Laboratory for Computer Science/Crypto / without hindrance. Massachusetts Institute of Technology /META-PARRESIAS AKOLUTOS:Acts 28:31 -.-. .-.. .. ..-. ..-. --- .-. -.. ... -.-. --- - - .- -. .- -. .. .- -. PGP key available via finger and from http://www.pdos.lcs.mit.edu/~cananian
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