Messages in this thread | | | Date | Mon, 17 Nov 1997 00:33:06 -0700 | From | "M. Patrick Goda" <> | Subject | Re: MSR: some random thoughts (it's saturday, sorry if they feel a , little week-endish...) |
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>>>>> "Rogier" == Rogier Wolff <R.E.Wolff@BitWizard.nl> writes:
Rogier> There is some discussion of what the "interface" should Rogier> be, right?
Rogier> How about this?
Rogier> rmsr is priviliged, and will signal "illegal instruction" Rogier> when run from userspace. If the option in the kernel is Rogier> enabled, the illegal instruction handler finds the Rogier> [r/w]msr instruction at the faulting address, and executes Rogier> the instruction for you and returns.
Well... I think we need to be careful about giving global access to WRMSR. The profiling software (or other MSR-accessing software) should do some checking first. However- RDMSR might be better to allow anyone use- but RDPMC exists for this purpose (for profiling MSRs). RDPMC allows (when CR4 is properly set) users to read the two profiling counters- not all MSR registers, just the profiling regs.
Patrick
-- --------------------------------------------------------------------- M. Patrick Goda W: (505)667-5386 Los Alamos National Laboratory H: (505)989-4506 Theoretical Astrophysics, T-6 MS B288 mpg@nea.lanl.gov Los Alamos, NM 87545 http://qso.lanl.gov/~mpg --------------------------------------------------------------------- Snappy Quote: "abcdefghijklmnopqrstuvwxyz"* *some assembly required ---------------------------------------------------------------------
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