linux-kernel - Re: 2.6.32-rc not booting with Xen-3.2 (bisected)

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Date:	Tue, 27 Oct 2009 19:10:30 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Christian Kujau <lists@...dbynature.de>
CC:	LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
	torvalds@...ux-foundation.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: 2.6.32-rc not booting with Xen-3.2 (bisected)

On 10/27/09 12:01, Christian Kujau wrote:
> On Tue, 27 Oct 2009 at 11:18, Jeremy Fitzhardinge wrote:
>   
>> $ gdb vmlinux
>> (gdb) x/i 0xffffffff812c50ad
>>     
> The value is always ffffffff812c50ad, gdb says:
>
> (gdb) x/i 0xffffffff812c50ad
> 0xffffffff812c50ad <xen_load_gdt_boot+252>:     ud2a  
>   

Please try the patch below.

>> Hm, sounds like a xenstored bug, or something is just pounding on it. 
>> Are there any other domains running, or other busy processes?
>>     
> Yes, there's another domU running. But the high load and xenstored 
> spinning is only happening when I try to start the domain with this 
> 2.6.32-rc kernel.
>   

That seems unlikely to be related (or a secondary effect of having a
domain crash).

    J

Subject: [PATCH] xen: set up mmu_ops before trying to set any ptes

xen_setup_stackprotector() ends up trying to set page protections,
so we need to have vm_mmu_ops set up before trying to do so.
Failing to do so causes an early boot crash.

[ Impact: Fix early crash under Xen. ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 3439616..23a4d80 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1075,6 +1075,8 @@ asmlinkage void __init xen_start_kernel(void)
 	 * Set up some pagetable state before starting to set any ptes.
 	 */
 
+	xen_init_mmu_ops();
+
 	/* Prevent unwanted bits from being set in PTEs. */
 	__supported_pte_mask &= ~_PAGE_GLOBAL;
 	if (!xen_initial_domain())
@@ -1099,7 +1101,6 @@ asmlinkage void __init xen_start_kernel(void)
 	 */
 	xen_setup_stackprotector();
 
-	xen_init_mmu_ops();
 	xen_init_irq_ops();
 	xen_init_cpuid_mask();
 


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