linux-kernel - Re: [BUG + PATCH/Bugfix] x86/lguest: fix pgdir pmd index calculation

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Message-ID: <20080229195838.GB21494@elte.hu>
Date:	Fri, 29 Feb 2008 20:58:38 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	"Ahmed S. Darwish" <darwish.07@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	LKML <linux-kernel@...r.kernel.org>, lguest@...abs.org,
	akpm <akpm@...ux-foundation.org>,
	Jeremy Fitzhardinge <jeremy@...source.com>
Subject: Re: [BUG + PATCH/Bugfix] x86/lguest: fix pgdir pmd index
	calculation


* Ahmed S. Darwish <darwish.07@...il.com> wrote:

> On the lguest _guest_ side, 'cpu_has_tsc' is _always_ false (due to 
> lguest using his own clocksource ?), thus a guest with a pentium+ cpu 
> always panics with:

does the "RDTSC" instruction work in an lguest guest? If not, then the 
lguest kernel is correct in not exposing it - and then the solution is 
to build a non-TSC guest kernel. Does the patch below help?

but if the RDTSC instruction does work in an lguest guest, then the 
proper approach would be to expose it in the CPU features.

	Ingo
---
 arch/x86/Kconfig.cpu |    1 +
 1 file changed, 1 insertion(+)

Index: linux-x86.q/arch/x86/Kconfig.cpu
===================================================================
--- linux-x86.q.orig/arch/x86/Kconfig.cpu
+++ linux-x86.q/arch/x86/Kconfig.cpu
@@ -393,6 +393,7 @@ config X86_P6_NOP
 config X86_TSC
 	def_bool y
 	depends on ((MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MVIAC7 || MGEODEGX1 || MGEODE_LX || MCORE2) && !X86_NUMAQ) || X86_64
+	depends on !LGUEST_GUEST
 
 # this should be set for all -march=.. options where the compiler
 # generates cmov.
--
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