RE: [Xen-devel] domains not shutting down properly -theproblemisbackagain

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> 
> On 02/01/2009 13:27, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
wrote:
> 
> > I added some debugging to the send_guest_global_virq code path too,
but
> > as soon as the DomU I created for testing shut down, my Dom0 became
> > unresponsive so I suspect I have botched my debug statements. It's
> > nearly 12:30am here and the server is at work so I'm done for the
day.
> >
> > The most frustrating thing is that I just know it's going to be some
> > stupid little configuration thing on my server causing all of
this!!!
> 
> Perhaps multiprocessor dom0, plus a bug in the dom0 kernel which means
> that
> the VCPU which Xen notifies for the virq is not the one which dom0
kernel
> is
> expecting to receive the notification to? What do you use as dom0
kernel?
> 

That appears to be the problem.

1. xenstore starts up and binds VIRQ_DOM_EXC to port 18
2. xend starts and sets the number of cpus to 1 (dom0-cpus = 1)
3. xen notifies xenstore on port=18, vcpu=1, but vcpu 1 doesn't exist
anymore so the event never gets anywhere

The curious thing is that IOCTL_EVTCHN_BIND_VIRQ explicitly sets vcpu =
0, so why is the event getting delivered to vcpu 1???

Thinking back, this bug must have reappeared once I changed dom0-cpus
from 0 to 1... wish I had clicked back then :(

James


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