Messages in this thread | | | Date | Sat, 02 Jan 1999 19:48:50 -0500 | From | Brian Gerst <> | Subject | Re: Patch for K6 sep flag |
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Brian Gerst wrote: > > This patch fixes /proc/cpuinfo for the K6 model 6. On this version of > the K6, bit 10 of the extended flags register denotes the SYSCALL/SYSRET > capability. On later models, bit 11 (the same as the PPro/PII) is used.
Digging a bit deeper into AMD's documentation, I found that this is only true for the stepping A of the model 6. Beginning with the B step model 6, bit 11 is used for SYSCALL/SYSRET. Bit 10 is now marked as "reserved", and probably should be ignored. I've been experimenting with implementing a SYSCALL handler, but the MSR that controls it seems to be unimplemented on my chip (K6-233, model 6, C step). I've wanted to upgrade anyways, so this is more incentive...
In short, my previous patch doesn't really work as advertised. Bit 10 now is either advertising a feature AMD isn't telling anybody about, or it is erroneous.
PS. A while back (a year ago?) somebody had posted a patch that started to implement SYSCALL. Does anybody remember who posted it or where I can find it?
--
Brian Gerst
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