Re: 2.6.22-rc1 does not boot on VIA C3_2 cause of X86_CMPXCHG64

From: Dave Jones
Date: Thu May 17 2007 - 02:19:06 EST


On Wed, May 16, 2007 at 09:51:36PM -0700, H. Peter Anvin wrote:
> Linus Torvalds wrote:
> >
> > On Wed, 16 May 2007, H. Peter Anvin wrote:
> >> It gets turned on by the code in arch/i386/kernel/cpu. It's just that
> >> the new code that Andi added runs during setup, i.e. in real mode, so
> >> *way* earlier than that.
> >
> > Ahh. Do we really need it that early?
>
> The reason to do it early is so that we can still get a message out if
> the CPU doesn't have the necessary features. This is generic code and
> not specific to CX8.
>
> Since I'm rewriting the setup code in C, I have added code to enable
> features on VIA and Transmeta CPUs (there was already code in there to
> enable features on AMD; Intel isn't known to hide any features other
> than PAE on 400 MHz FSB Pentium-M.)
>
> I think the early feature detection makes good sense. It's a heckuva
> lot nicer to get a message on your screen saying that you can't boot
> this kernel on this CPU than a crash, or an early_printk which may never
> actually get to you.

agreed, though we'll still need something for .22 (I'm assuming your rework
isn't intended for .22)

Dave

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http://www.codemonkey.org.uk
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