Re: [Xen-devel] Regression, host crash with 4.5rc1

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.11.14 at 21:05, <sflist@xxxxxxxxx> wrote:
> On 11/10/2014 0:51, Jan Beulich wrote:
>> Raising the kernel log level to maximum too would have helped.
> 
> Okay, I've done that and the output is here, let me know if you have any 
> preferred logging flags instead:
> 
> http://pastebin.com/M3yvWNTT 

Hmm, I can't spot any further useful messages there, which may be
due to the log having got partly garbled.

>> Regardless of that, the first device showing anomalies here appears
>> to be the UHCI controller:
>>
>>      [  147.415713] usb 7-1: reset low-speed USB device number 2 using 
> uhci_hcd
>>
>> while booting the guest.
> 
> I assume this is related to the USB device (a keyboard) I'm passing 
> through to the domU.

But not by passing through the HCD I assume, since the log only
shows the VGA card being consumed by pciback?

>> And these
>>
>>      [  199.775209] pcieport 0000:00:03.0: AER: Multiple Corrected error 
> received: id=0018
>>      [  199.775238] pcieport 0000:00:03.0: PCIe Bus Error: 
> severity=Corrected, type=Data Link Layer, id=0018(Transmitter ID)
>>      [  199.775251] pcieport 0000:00:03.0:   device [8086:340a] error 
> status/mask=00001100/00002000
>>      [  199.775255] pcieport 0000:00:03.0:    [ 8] RELAY_NUM Rollover
>>      [  199.775258] pcieport 0000:00:03.0:    [12] Replay Timer Timeout
>>
>> hint at a problem in the system's design. 00:03.0 is the parent bridge
>> of 02:00.0 (and from what I can tell that's the only device behind that
>> bridge), and hence the above messages can only reasonably have
>> their origin at the passed through VGA device.
> 
> You are correct that the VGA card is the only device on 03.0:
> [...]
> What problem in the system's design does this hint at?

It's not the topology that I referred to, but last events reported in
the quoted log lines above. Such should not be happening repeatedly
on a properly functioning system.

>> IOW it may well be that
>> you were just lucky that things worked earlier on.
> 
> Certainly possible but this is a very common machine in the corporate 
> world -- a Lenovo ThinkStation D20 running the X58 chipset. If it's an 
> inherent defect in the machine and somebody else hasn't already tripped 
> over it I would be very surprised.

Except that pass-through, and especially VGA pass-through, aren't
being used by that many people.

Jan


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