[PATCH] fix 32 bit guest freeze on second reboot

[PATCH] fix 32 bit guest freeze on second reboot

[Joerg Roedel]

From: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>

This patch fixes a bug detected with 32 bit Linux guests. There the
second try to reboot hangs the guest machine. It seems to be necessary
to fix all dataseg registers for 32 bit guests.

Signed-off-by: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>

-- 
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG



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[PATCH] fix 32 bit guest freeze on second reboot

[Joerg Roedel]

[-- Attachment #1: Type: text/plain, Size: 432 bytes --]

From: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>

This patch fixes a bug detected with 32 bit Linux guests. There the
second try to reboot hangs the guest machine. It seems to be necessary
to fix all dataseg registers for 32 bit guests. This time with a patch
attached.

Signed-off-by: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>

-- 
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG

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Index: qemu/qemu-kvm.c
===================================================================
--- qemu/qemu-kvm.c	(revision 4384)
+++ qemu/qemu-kvm.c	(working copy)
@@ -195,6 +195,8 @@
 	    if (!(env->cr[0] & CR0_PG_MASK)) {
 		    fix_realmode_dataseg(&sregs.ds);
 		    fix_realmode_dataseg(&sregs.es);
+		    fix_realmode_dataseg(&sregs.fs);
+		    fix_realmode_dataseg(&sregs.gs);
 		    fix_realmode_dataseg(&sregs.ss);
 	    }
     }

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[-- Attachment #4: Type: text/plain, Size: 186 bytes --]

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Re: [PATCH] fix 32 bit guest freeze on second reboot

[Dor Laor]

>From: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
>
>This patch fixes a bug detected with 32 bit Linux guests. There the
>second try to reboot hangs the guest machine. It seems to be necessary
>to fix all dataseg registers for 32 bit guests. This time with a patch
>attached.

Although it seems logical to apply the patch anyway, it does'nt fix the
problem. On 80% of the times I tried rebooting debian 32bit guest, the
second tried the guest did not manage to complete the reboot andwas
stuck.

>
>Signed-off-by: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
>
>--
>Joerg Roedel
>Operating System Research Center
>AMD Saxony LLC & Co. KG

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Re: [PATCH] fix 32 bit guest freeze on second reboot

[Joerg Roedel]

On Mon, Feb 05, 2007 at 06:53:40AM -0800, Dor Laor wrote:
> 
> >From: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
> >
> >This patch fixes a bug detected with 32 bit Linux guests. There the
> >second try to reboot hangs the guest machine. It seems to be necessary
> >to fix all dataseg registers for 32 bit guests. This time with a patch
> >attached.
> 
> Although it seems logical to apply the patch anyway, it does'nt fix the
> problem. On 80% of the times I tried rebooting debian 32bit guest, the
> second tried the guest did not manage to complete the reboot andwas
> stuck.

Ok. Right. Seems I should have did more tests with the patch before
submission. I will further debug it next time.

Joerg

-- 
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG



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Re: [PATCH] fix 32 bit guest freeze on second reboot

[Avi Kivity]

Joerg Roedel wrote:
> From: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
>
> This patch fixes a bug detected with 32 bit Linux guests. There the
> second try to reboot hangs the guest machine. It seems to be necessary
> to fix all dataseg registers for 32 bit guests. This time with a patch
> attached.
>
> Signed-off-by: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
>
>   

Applied, thanks.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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