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Date: Tue, 26 Mar 2013 16:39:30 +0000
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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To: Arnd Bergmann <arnd@arndb.de>
CC: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
        "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
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        Ian Campbell <Ian.Campbell@citrix.com>,
        "rob.herring@calxeda.com" <rob.herring@calxeda.com>,
        "will.deacon@arm.com" <will.deacon@arm.com>,
        "marc.zyngier@arm.com" <marc.zyngier@arm.com>
Subject: Re: [PATCH v2 5/6] xenvm: add a simple PSCI node and a second cpu
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On Tue, 26 Mar 2013, Arnd Bergmann wrote:
> On Tuesday 26 March 2013, Stefano Stabellini wrote:
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> > CC: rob.herring@calxeda.com
> > CC: will.deacon@arm.com
> > CC: marc.zyngier@arm.com
> > CC: arnd@arndb.de
> 
> I wonder how this is supposed to work on real systems. Shouldn't the dt
> blob be filled out with the correct number of CPUs at the time you start
> the guest? 
> This change looks like you just make all guests use a hardcoded
> set of two CPUs instead of just one, but you probably want to allow any
> number between 1 and the number of physically present cores.

That's right, the DT passed on to the guests is generated by the
hypervisor. This is just an example, adding a cpu and a psci node is
just meant to make it clear that Xen supports multi-vcpu guests using
PSCI to bootstrap secondary cpus.