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[Xen-devel] Re: xen dependant on pcpu 0 ?

To: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: [Xen-devel] Re: xen dependant on pcpu 0 ?
From: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Date: Tue, 12 Oct 2010 18:13:02 +0100
Cc: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
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On Tue, 2010-10-12 at 17:44 +0100, Konrad Rzeszutek Wilk wrote: 
> On Tue, Oct 12, 2010 at 06:28:13PM +0200, Sander Eikelenboom wrote:
> > Hi Keir,
> > 
> > Does xen and/or the xen console depend on physical cpu 0 ?
> Usually the console for Dom0, and I think all other domains go
> through CPU0. Let me CC Ian here, who has been mucking in this
> area and found some bugs (and produced fixes).
> Ian, that bug you found with not clearing the eventchannel - that
> wouldn't have an impact here, right?

I don't think so. That issue was related to evtchn delivery which is to
VCPUs not PCPUs. I don't think it was specific to VCPU0 either -- it
just happened that the particular evtchn was generally tied to VCPU0 by

I don't think the problem would happen for PIRQs anyway since the
->startup method for that IRQ chip includes an explicit rebind of the
evtchn to a VCPU, it's only dynirqs which have the issue.


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