Re: [Xen-devel] [PATCH 5/9] ARM: Xen: fix initial build problems:

[Ian Campbell <Ian.Campbell@citrix.com>]

On Wed, 2012-10-10 at 15:47 +0100, Stefano Stabellini wrote:
> On Wed, 10 Oct 2012, Ian Campbell wrote:
> > On Tue, 2012-10-09 at 19:21 +0100, Arnd Bergmann wrote:
> > > On Tuesday 09 October 2012, Stefano Stabellini wrote:
> > > > >  config XEN
> > > > >       bool "Xen guest support on ARM (EXPERIMENTAL)"
> > > > >       depends on EXPERIMENTAL && ARM && OF
> > > > > +     depends on !CPU_V6
> > > > >       help
> > > > >         Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
> > > > 
> > > > Considering that we rely on the virtualization extensions, this one can
> > > > be:
> > > > 
> > > >     depends on CPU_V7
> > > > 
> > > > The rest looks fine. I can submit a second patch to change !CPU_V6 into
> > > > CPU_V7 later, if you prefer.
> > > 
> > > CPU_V6 and CPU_V7 are not exclusive, I saw the problem when building a
> > > combined kernel for both V6 and V7. The code also needs to depend on ARMv7
> > > with virtualization extensions, but that is a different issue. We don't
> > > actually have a configuration symbol for that yet, as far as I can tell.
> > 
> > I don't think the guest kernels (including dom0) need the extensions to
> > run under Xen, they are only need by Xen itself. The guests should just
> > see a relatively normal v7 processor. 
> > 
> > Stefano, does that sound right?
> 
> Keep in mind that we are using HVC to issue hypercalls, and HVC has been
> introduced with the virtualization extensions, if I am not mistaken.

I think we can ignore that in this context since it is only used by bits
which are already virtualisation aware -- i.e. you wouldn't want to add
it to the Kconfig as a dependency for Xen.

Ian.