Re: [Xen-devel] IO-APIC interrupts getting stuck

[Roger Pau Monnà <roger.pau@xxxxxxxxxx>]

El 02/01/15 a les 17.20, Jan Beulich ha escrit:
>>>> Roger Pau MonnÃ<roger.pau@xxxxxxxxxx> 12/22/14 7:44 PM >>>
>> No, the same box I have with Linux doesn't use the IO-APIC re-route
>> quirk. I've also tested this on different hardware and when using
>> FreeBSD with the new IO APIC Ack method I always end up in this stuck
>> state, so I don't think it's a hardware errata/issue.
> 
> Understood. I'm afraid there's not much we can do here without you gathering
> more data - one particularly useful thing would be kind of a trace of states 
> for
> the first respective IRQ delivery inside Xen, allowing to then compare the
> progress with PVH Linux and FreeBSD. There must be a difference after all.

What I said above was not completely true, the other box I've used for
testing was also a Nehalem with two IO-APICs. Now I've tested on a
Nehalem (X3450) with a single IO-APIC and it works fine. I'm still not
sure if this issue is limited to the Nehalem family with two IO-APICs,
or if newer families also have the same issue if more than one IO-APIC
is present. Switching to the "old" IO-APIC ack mode seems to solve the
problem (or at least mitigate it).

This is quite bad on those systems because as soon as one of the IO-APIC
IRQs gets stuck everything starts falling apart and MSI interrupts also
get stuck.

Roger.

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