Re: [Xen-devel] [BUG] panic: "IO-APIC + timer doesn't work" - several people have reproduced

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.02.2020 22:45, Andrew Cooper wrote:
> On 18/02/2020 18:43, Jason Andryuk wrote:
>> On Mon, Feb 17, 2020, 8:22 PM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 
>> wrote:
>>> On 17/02/2020 20:41, Jason Andryuk wrote:
>>>> On Mon, Feb 17, 2020 at 2:46 PM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 
>>>> wrote:
>>>>> On 17/02/2020 19:19, Jason Andryuk wrote:
>>>>>> enabling vecOn Tue, Dec 31, 2019 at 5:43 AM Aaron Janse 
>>>>>> <aaron@xxxxxxxxx> wrote:
>>>>>>> On Tue, Dec 31, 2019, at 12:27 AM, Andrew Cooper wrote:
>>>>>>>> Is there any full boot log in the bad case?  Debugging via divination
>>>>>>>> isn't an effective way to get things done.
>>>>>>> Agreed. I included some more verbose logs towards the end of the email 
>>>>>>> (typed up by hand).
>>>>>>>
>>>>>>> Attached are pictures from a slow-motion video of my laptop booting. 
>>>>>>> Note that I also included a picture of a stack trace that happens 
>>>>>>> immediately before reboot. It doesn't look related, but I wanted to 
>>>>>>> include it anyway.
>>>>>>>
>>>>>>> I think the original email should have said "4.8.5" instead of "4.0.5." 
>>>>>>> Regardless, everyone on this mailing list can now see all the boot logs 
>>>>>>> that I've seen.
>>>>>>>
>>>>>>> Attaching a serial console seems like it would be difficult to do on 
>>>>>>> this laptop, otherwise I would have sent the logs as a txt file.
>>>>>> I'm seeing Xen panic: "IO-APIC + timer doesn't work" on a Dell
>>>>>> Latitude 7200 2-in-1.  Fedora 31 Live USB image boots successfully.
>>>>>> No way to get serial output.  I manually recreated the output before
>>>>>> from the vga display.
>>>>> We have multiple bugs.
>>>>>
>>>>> First and foremost, Xen seems totally broken when running in ExtINT
>>>>> mode.  This needs addressing, and ought to be sufficient to let Xen
>>>>> boot, at which point we can try to figure out why it is trying to fall
>>>>> back into 486(ish) compatibility mode.
>> Xen has "enabled ExtINT on CPU#0" while linux has "masked ExtINT on
>> CPU#0" so linux isn't using ExtINT?
> 
> It would appear not.  Even more concerningly, on my Kabylake box,
> 
> # xl dmesg | grep ExtINT
> (XEN) enabled ExtINT on CPU#0
> (XEN) masked ExtINT on CPU#1
> (XEN) masked ExtINT on CPU#2
> (XEN) masked ExtINT on CPU#3
> (XEN) masked ExtINT on CPU#4
> (XEN) masked ExtINT on CPU#5
> (XEN) masked ExtINT on CPU#6
> (XEN) masked ExtINT on CPU#7
> 
> which at first glance suggests that we have something asymmetric being
> set up.

That's perfectly normal - ExtINT may be enabled on just one CPU,
and that's CPU0 in our case (until such time that we would want
to be able to offline CPU0).

Jan

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