Re: [Xen-devel] Using debug-key 'o: Dump IOMMU p2m table, locks up machine

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.09.12 at 12:25, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
> Wednesday, September 5, 2012, 12:14:02 PM, you wrote:
>>>>> On 04.09.12 at 18:43, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
>>> ...........................<0>AMD-Vi: IO_PAGE_FAULT: domain = 0, device id 
>>> = 
>>> 0x0a06, fault address = 0xc2c2c2c0
> 
>> Looks like use of uninitialized memory (assuming you're using a
>> debug hypervisor, that's the pattern scrub_one_page() puts
>> there). But it's unclear to me what device should be doing any
>> I/O at that point (and even if one does, how it would get the
>> bad address loaded). What is 0a:00.6?
> 
> since 4.2-rc4 is still unstable it has debug=y for what i know, so yes.
> This particular IO_PAGE_FAULT happened before the kernel loads, so the 
> kernel and pciback shouldn't be causing the issue one would say.
> With pciback i'm hiding 03:06.0, 04:00.*, 05:00.0, 0a:00.* and 07:00.0 at 
> boot.
> 
> Is there any code i could add to get more info where it comes from ?

Hardly, since those accesses are asynchronous to what the CPUs
do. But ...

> 0a:00.6 USB controller: NetMos Technology MCS9990 PCIe to 4ÃPort USB 2.0 Host 
> Controller

... are your keyboard/mouse perhaps connected to this one? In
which case I'd suppose the 1:1 tables set up for Dom0 might not
be complete. Wei?

Jan

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