Re: [BUG] x86 kenel won't boot under Virtual PC

From: Linus Torvalds
Date: Mon Sep 08 2008 - 11:10:43 EST

On Sun, 7 Sep 2008, H. Peter Anvin wrote:
> Under that logic we shouldn't even have CPU configurables, since you want it
> to "just work" whatever crap you're running on. That is EXACTLY what

I dunno.. Event he help-text doesn't actually agree with that:

config X86_GENERIC
bool "Generic x86 support"
depends on X86_32
Instead of just including optimizations for the selected
x86 variant (e.g. PII, Crusoe or Athlon), include some more
generic optimizations as well. This will make the kernel
perform better on x86 CPUs other than that selected.

This is really intended for distributors who need more
generic optimizations.

Also, quite frankly, while the CPU processor type message says

The kernel will not necessarily run on earlier architectures than
the one you have chosen, e.g. a Pentium optimized kernel will run on
a PPro, but not necessarily on a i486.

I thought you agreed that CPU virtualization can be a problem? That was
the whole excuse for why the dynamic code was changed. Why would it not be
true for the static code?

The fact is, if you want to run on a Core2 or other modern CPU, then
"Virtual PC" is apparently buggy in this respect. You worked around it for
the dynamic choice - but that's totally _pointless_ if you then don't want
to work around it for the static one.

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