Re: [Xen-devel] [PATCH] Remove hardcoded xen-platform device initialization

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Paolo Bonzini [mailto:paolo.bonzini@xxxxxxxxx] On Behalf Of Paolo
> Bonzini
> Sent: 14 June 2013 15:58
> To: Paul Durrant
> Cc: Ian Campbell; Stefano Stabellini; qemu-devel@xxxxxxxxxx; xen-
> devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH] Remove hardcoded xen-platform device
> initialization
> 
> Il 14/06/2013 10:11, Paul Durrant ha scritto:
> > I think we're still going to need -M xenpv, I think; it's quite
> > distinct from pc.
> 
> Of course!  Even more: "-M xenpv" should be reused on ARM.
> 
> > I guess we could use -M pc for HVM and gate the
> > accel code as you suggest but, if that's the way we're going, it
> > would seem more logical just to ditch the accel code for xenpv
> > completely (assuming we can do all we need from the machine init) and
> > then use -M pc -accel=xen for HVM guests going forward.
> 
> There is common code between pv and fv, and that one definitely belongs
> in xen_init.  Most fv-only code probably should be in pc_init.  The rest
> should move to xen_init though, because it would apply just as well for
> example to Q35.  It's a bit ugly to have fv-only code there, but it's
> better than having a Xen-specific machine type.  Xen/KVM/TCG should be
> as similar as possible at the QEMU level, any difference should be
> handled in the toolstack.
> 
> > But that does
> > rather screw up my autodiscovery plans because I would not know, for
> > a given qemu binary, which machine type to use.
> 
> There's no need for that.  4.4 can just use "-M pc" unconditionally,
> <=4.3 will just use "-M xenfv" unconditionally.
> 
> > If I create a new
> > xenfv-2.0 machine type though I *can* do auto discovery... in which
> > case do we need the -accel=xen option at all?
> 
> Yes.  Please try not do things differently from other accelerators.
> 

Ok. I guess we can have the ability to override the machine type in the VM 
config, so you could still kick off an older qemu with a newer libxl - but it 
sounds like the auto-discovery idea is a no-go then.

  Paul
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