From: "H. Peter Anvin" <hpa@zytor.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>,
"Luis R. Rodriguez" <mcgrof@gmail.com>,
linux kernel <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@kernel.org>,
Ivan Seskar <Seskar@winlab.rutgers.edu>,
jfm3 <jfm3@winlab.rutgers.edu>, Sujith <m.sujith@gmail.com>
Subject: Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot
Date: Sat, 26 Jul 2008 14:35:39 -0400 [thread overview]
Message-ID: <488B6E7B.9040908@zytor.com> (raw)
In-Reply-To: <87prp07b0y.fsf@basil.nowhere.org>
Andi Kleen wrote:
>
> This was originally supposed to be handled in the early real mode
> head.S code. That is why I put the CPUID checking code in there
> to error out early when you can still print to the console
> using the BIOS functions.
>
> I suspect this regressed when that code was moved to C, because
> now the C compiler generates CMOV early.
>
> How about always building the real mode C code with -march=i386?
> It is not performance critical so that is ok.
>
The real mode code *is* compiled with -march=i386, and in the CMOV case
it will err out with a legible message.
The issue isn't CMOV at all, it's with long NOPs, which don't have a
CPUID bit -- they're supposed to be supported if family >= 6, but some
VIA chips violate that condition.
-hpa
next prev parent reply other threads:[~2008-07-26 18:36 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-21 13:14 Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot Luis R. Rodriguez
2008-07-21 13:23 ` H. Peter Anvin
2008-07-21 14:01 ` Luis R. Rodriguez
2008-07-21 23:24 ` H. Peter Anvin
2008-07-22 4:47 ` Luis R. Rodriguez
2008-07-22 13:10 ` H. Peter Anvin
2008-07-22 17:10 ` Jeff Garzik
2008-07-22 18:21 ` H. Peter Anvin
2008-07-22 18:33 ` Jeff Garzik
2008-07-22 18:41 ` H. Peter Anvin
2008-07-22 23:28 ` Jeff Garzik
2008-07-23 0:31 ` H. Peter Anvin
2008-07-22 13:14 ` Ingo Molnar
2008-07-22 13:24 ` H. Peter Anvin
2008-07-22 13:46 ` Ingo Molnar
2008-07-22 13:54 ` H. Peter Anvin
2008-07-26 18:31 ` Andi Kleen
2008-07-26 18:35 ` H. Peter Anvin [this message]
2008-07-26 18:44 ` Andi Kleen
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