Subject: Re: new sysctl: hw.cpu_isa
To: Simon Burge <firstname.lastname@example.org>
From: Bill Sommerfeld <email@example.com>
Date: 11/13/2000 10:00:55
> Note that this is not designed for fine-grained feature selection, like
> the alpha amask or x86 CPUID.
This is not architecturally correct for x86.
intel's processor documentation is *very* explicit that, in
architectures which support the CPUID feature mask, it is never
correct to assume that a feature is present because the processor type
is greater than some threshhold.
- Certain features have been removed from the architecture entirely
(e.g., processor serial number)
- certain features can be disabled by the BIOS before boot.
- given the multiple parallel tracks of development even within
Intel, features don't appear in a linear order. If you add in AMD and
Cyrix and the like, life gets even more nonlinear..