From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
linux@sandersweb.net, linux-kernel@vger.kernel.org,
the arch/x86 maintainers <x86@kernel.org>,
Andi Kleen <andi-suse@firstfloor.org>
Subject: Re: [BUG] x86 kenel won't boot under Virtual PC
Date: Mon, 8 Sep 2008 17:23:30 +0200 [thread overview]
Message-ID: <20080908152330.GA9784@elte.hu> (raw)
In-Reply-To: <alpine.LFD.1.10.0809080805240.3117@nehalem.linux-foundation.org>
* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 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
> > CONFIG_X86_GENERIC means
>
> I dunno.. Event he help-text doesn't actually agree with that:
>
> config X86_GENERIC
> bool "Generic x86 support"
> depends on X86_32
> help
> 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.
yes. X86_P6_NOPS is a totally insignificant optimization and if it makes
_any_ CPU not boot (be that virtual or real), then it's frankly not
worth it.
David, exactly how does the kernel fail to boot with latest -git?
(v2.6.27-rc5-313-g64f996f or later) Does detect_nopl() run? It really
should, and it should detect the non-working instructions.
Ingo
next prev parent reply other threads:[~2008-09-08 15:24 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-31 18:22 [BUG] x86 kenel won't boot under Virtual PC David Sanders
2008-08-31 18:47 ` Linus Torvalds
2008-08-31 19:27 ` Arjan van de Ven
2008-08-31 19:39 ` Linus Torvalds
2008-09-05 15:38 ` David Sanders
2008-09-05 16:15 ` Jan Beulich
2008-09-05 16:39 ` Linus Torvalds
2008-09-05 18:43 ` Ingo Molnar
2008-09-05 20:06 ` H. Peter Anvin
2008-09-05 19:08 ` Jeremy Fitzhardinge
2008-09-05 20:12 ` H. Peter Anvin
2008-09-05 16:30 ` Linus Torvalds
2008-09-05 17:55 ` Andi Kleen
2008-08-31 20:03 ` David Sanders
2008-09-01 20:23 ` David Sanders
2008-09-01 22:22 ` Linus Torvalds
2008-09-02 12:08 ` David Sanders
2008-09-02 18:12 ` Linus Torvalds
2008-09-02 18:44 ` David Sanders
2008-09-03 11:09 ` Peter Zijlstra
2008-09-03 11:20 ` David Sanders
[not found] ` <48C1C156.9080003@zytor.com>
2008-09-07 20:07 ` David Sanders
2008-09-07 23:22 ` David Sanders
2008-09-08 1:48 ` H. Peter Anvin
2008-09-08 2:49 ` David Sanders
2008-09-08 4:04 ` H. Peter Anvin
2008-09-08 9:42 ` Andi Kleen
2008-09-08 13:25 ` David Sanders
2008-09-08 15:09 ` Linus Torvalds
2008-09-08 15:23 ` Ingo Molnar [this message]
2008-09-08 15:36 ` H. Peter Anvin
2008-09-08 15:38 ` David Sanders
2008-09-08 15:38 ` H. Peter Anvin
2008-09-08 15:45 ` Andi Kleen
2008-09-08 15:43 ` H. Peter Anvin
2008-09-08 15:50 ` H. Peter Anvin
2008-09-08 15:50 ` Andi Kleen
2008-09-08 15:50 ` H. Peter Anvin
2008-09-08 15:57 ` Andi Kleen
2008-09-08 15:54 ` H. Peter Anvin
2008-09-08 16:07 ` Linus Torvalds
2008-09-08 16:13 ` H. Peter Anvin
2008-09-08 16:15 ` H. Peter Anvin
2008-09-08 16:26 ` David Sanders
2008-09-08 16:20 ` Linus Torvalds
2008-09-08 16:32 ` H. Peter Anvin
2008-09-08 17:02 ` Ingo Molnar
2008-09-08 16:34 ` david
2008-09-08 16:42 ` H. Peter Anvin
2008-09-08 18:51 ` david
2008-09-08 16:59 ` Linus Torvalds
2008-09-08 17:00 ` Andi Kleen
2008-09-08 17:04 ` Linus Torvalds
2008-09-08 17:08 ` H. Peter Anvin
2008-09-08 17:12 ` H. Peter Anvin
2008-09-08 17:41 ` Linus Torvalds
2008-09-08 17:38 ` Linus Torvalds
2008-09-08 17:59 ` H. Peter Anvin
2008-09-08 19:09 ` H. Peter Anvin
2008-09-08 22:42 ` Linus Torvalds
2008-09-08 17:18 ` Andi Kleen
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