Re: NetBSD dom0 PVH: hardware interrupts stalls

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.11.2020 10:28, Manuel Bouyer wrote:
> On Wed, Nov 18, 2020 at 10:16:17AM +0100, Jan Beulich wrote:
>> On 17.11.2020 17:40, Manuel Bouyer wrote:
>>> On Tue, Nov 17, 2020 at 04:58:07PM +0100, Roger Pau Monné wrote:
>>>> [...]
>>>>
>>>> I have attached a patch below that will dump the vIO-APIC info as part
>>>> of the 'i' debug key output, can you paste the whole output of the 'i'
>>>> debug key when the system stalls?
>>>
>>> see attached file. Note that the kernel did unstall while 'i' output was
>>> being printed, so it is mixed with some NetBSD kernel output.
>>
>> Could you try to run Xen's serial port without use of any IRQ
>> (i.e. in "polling" mode), in an attempt to avoid this unstalling
>> (which is likely to render the resulting output at least in part
>> meaningless)?
> 
> It there a boot line option for that ?

Yes, com<N>= has a field for this:

### com1
### com2
> `= 
> <baud>[/<base-baud>][,[DPS][,[<io-base>|pci|amt][,[<irq>|msi][,[<port-bdf>][,[<bridge-bdf>]]]]]]`

with

* `<irq>` is the IRQ number to use, or `0` to use the UART in poll
  mode only, or `msi` to set up a Message Signaled Interrupt.

Jan