From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: dom0 crash with unstable
Date: Tue, 06 Oct 2009 11:56:05 -0700
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To: "Bryan D. Payne" <bryan@thepaynes.cc>
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On 10/06/09 11:25, Bryan D. Payne wrote:
> (gdb) x/i 0xffffffff8100930a
> 0xffffffff8100930a <hypercall_page+778>:	add    %al,(%rax)
>   
778/32 = hypercall 24 = vcpuop.  Probably idling.
> (gdb) x/i 0xffffffff811fea48
> 0xffffffff811fea48 <delay_tsc+62>:	
>     cmpq   $0x0,0x632538(%rip)        # 0xffffffff81830f88 <pv_cpu_ops+264>
>   

That's almost certainly a kernel panic of some kind.  Working out where
it came from will be rather tedious: you need to look through the stack
dump to find code-ish looking addresses then x/i them (they'll be the
same basic format as 0xffffffff8xxxxxxx).

(I really need to work out why they tend not to get printed.)

>> What happens if you boot dom0 with fewer cpus?
>>     
> I tried adding "maxcpus=1" to the linux kernel line in grub.  I used
> this in conjunction with the "dom0_mem=2G" option for xen.  Dom0 still
> crashes the same as without the maxcpus option.
>
> Just for kicks, I tried a few other options...
>
> * setting mem=4G with dom0_mem=2G seemed still resulted in random dom0 crashing
> * setting noapic resulted in a consistent crash within Xen:
>
> (XEN) ----[ Xen-3.5-unstable  x86_64  debug=y  Not tainted ]----
> (XEN) CPU:    0
> (XEN) RIP:    e008:[<ffff82c48014fe29>] add_pin_to_irq+0x24/0xcc
> (XEN) RFLAGS: 0000000000010296   CONTEXT: hypervisor
>   

That shouldn't happen.  Sounds like it might be fall-out from the recent
interrupt changes in Xen.  Did you supply "noapic" to Xen, dom0 or both?

    J