Messages in this thread | | | Date | Thu, 15 Jul 1999 20:50:42 +0200 (MET DST) | From | "Maciej W. Rozycki" <> | Subject | Re: [miniPATCH] about cr4 : SysRq Show Reg |
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On Thu, 15 Jul 1999, Masahiro Adegawa wrote:
> we get cr4 when `SysRq: Show Regs'. > But I do not know the best effective judging conditions of CR4.
You should probably use a bit mask. It seems X86_FEATURE_VME is best for Intel CPUs as all Intels that have CR4 implement this feature while there exist Intel CPUs that do have CR4 but do not support X86_FEATURE_PSE. But I am not sure about other vendors.
To be on the safe side I would test features that have their respective CR4 bits and assume it's present whenever any of them is set. AFAIK, the appropriate mask is: (X86_FEATURE_VME | X86_FEATURE_DE | X86_FEATURE_PSE | X86_FEATURE_TSC | X86_FEATURE_PAE | X86_FEATURE_MCE | X86_FEATURE_PGE | X86_FEATURE_FXSR | X86_FEATURE_25).
X86_FEATURE_25 will probably called X86_FEATURE_XMM one day.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
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