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

["H. Peter Anvin" <hpa@zytor.com>]

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.

	-hpa