Re: Aw: Re: [help] Xen 4.14.5 on Devuan 4.0 Chimaera, regression from Xen 4.0.1

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.03.2023 20:09, Denis wrote:
> On 14.03.2023 17:59, Jan Beulich wrote:
>> On 14.03.2023 17:45, Denis wrote:
>>> On 14.03.2023 16:37, Jan Beulich wrote:
>>>> On 14.03.2023 15:53, Denis wrote:
>>>>> What tests could I do or what info should I provide to help?
>>>>
>>>> Boot plain Linux (no Xen underneath) and collect the full set of kernel
>>>> boot messages (some distros store this at /var/log/boot.msg); "full"
>>>> meaning we want to be able to see all output regardless of log-level.
>>>
>>> I'll attach some files from /var/log.
>>
>> Thanks, and there we go:
>>
>> [    0.121463] AMD-Vi: [Firmware Bug]: : No southbridge IOAPIC found
>> [    0.121495] AMD-Vi: Disabling interrupt remapping
>>
>> It's 5.10, so somewhat old already, but from looking at the code I wouldn't
>> expect anything else with a newer kernel.
> 
> So older versions (be it Kerenel or Xen) didn't look for a secondary 
> Southbridge IOAPIC?
> If so, was that a change made due to the vulnerabilities in Xen due to 
> passed-through
> devices?

No, both Xen's and Linux'es commits clearly say that one of the things
observed non-working in such cases was the timer interrupt (which in
turn would prevent Xen [or Linux] from booting successfully).

> Just asking because age-old distros worked as it seems...

Except on certain systems.

Jan