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Message-ID: <1368087121.17285.86.camel@zakaz.uk.xensource.com>
Subject: Re: [Xen-devel] [PATCH v3 4/4] xen/arm: account for stolen ticks
From: Ian Campbell <Ian.Campbell@citrix.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: Marc Zyngier <marc.zyngier@arm.com>,
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Date: Thu, 9 May 2013 09:12:01 +0100
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On Wed, 2013-05-08 at 18:03 +0100, Stefano Stabellini wrote:
> > What if we have Xen support enabled but don't run as a Xen guest?
> 
> That's fine as long as the Xen runstate_memory_area interface is
> available.
> Usually I am a great fun of feature flags, so that every feature can be
> dynamically enabled or disabled and an hypervisor interface can be only
> partially implemented.
> 
> However the runstate_memory_area is very old and I would consider it
> one of the core interfaces that need to be available in order to claim
> "Xen compatibility".

I think Marc meant "what if CONFIG_XEN=y but we are running on KVM?". In
that case we wont have set either of the paravirt_steal*_enabled static
keys and so the hook won't be called.

> > > +	static_key_slow_inc(&paravirt_steal_enabled);
> > > +	static_key_slow_inc(&paravirt_steal_rq_enabled);
> > > +


Ian.