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

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Wednesday, September 5, 2012, 12:40:31 PM, you wrote:

>>>> 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?

Nope this machine is running without any keyboard/mouse, the USB controller at 
present has only one device connected to it:
in the pv guest lsusb:
Bus 007 Device 002: ID 10cf:5500 Velleman Components, Inc. 8055 Experiment 
Interface Board (address=0)

And as i said, the hardware didn't change between my switch from xen-4.1.3 to 
xen-4.2.

But i will revert to 4.1 and see if i can spot any difference in xl dmesg 
between the two.


> Jan



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