linux-kernel - Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87ljzo7aeo.fsf@basil.nowhere.org>
Date:	Sat, 26 Jul 2008 20:44:31 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	"Luis R. Rodriguez" <mcgrof@...il.com>,
	linux kernel <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...nel.org>,
	Ivan Seskar <Seskar@...lab.rutgers.edu>,
	jfm3 <jfm3@...lab.rutgers.edu>, Sujith <m.sujith@...il.com>
Subject: Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot

"H. Peter Anvin" <hpa@...or.com> writes:
>
> 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.

Ah yes I realized that about 1 minute after sending the original mail %)
Sorry for the noise. The only way to handle this is probably to add
special quirks. Should check with Centaur for the exact CPUID signatures
of these CPUs.

Or perhaps just stop using the special nops. It was always unclear
if optimizing nops was really worth it.

-Andi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/