Re: [Xen-devel] [PATCH] x86/apic/x2apic: Share IRQ vector between cluster members only when no cpumask is specified

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 08/07/2017 10:52 AM, Jan Beulich wrote:
>>>> Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 08/07/17 4:39 PM >>>
>> On 07/08/17 09:18, Jan Beulich wrote:
>>> Wouldn't it be sufficient for people running into vector shortage due to
>>> sharing to specify "x2apic_phys" on the command line?
>> Had XenServer noticed this change in default earlier, I would have
>> insisted that you make x2apic_phys the default.
> Change in default? About five and a half years ago I did implement cluster
> mode properly, but I wasn't able to spot a commit that changed the
> default from physical to cluster.
>
>> On affected systems, problem manifests as an upgrade where the new
>> hypervisor doesn't boot.  Recovering from this requires human
>> intervention during the server boot.
> This needs some more explanation: Why would the hypervisor not boot?
> Even if you said Dom0 didn't boot, it wouldn't really be clear to me why,
> as running out of vectors would likely occur only after critical devices
> had their drivers loaded.


If your critical device is a networking card with lots of functions? In
my case I had two cards. The first one was plumbed properly but the
second failed. It so happened that only the first one was required to
boot but I can see that in another configuration an init script might
require both to be initialized.


-boris

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