Re: [PATCH 0 of 5] PV on HVM Xen

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Mar 17, 2010 at 05:38:37PM +0800, Sheng Yang wrote:
> On Monday 15 March 2010 20:22:23 Stefano Stabellini wrote:
> > On Mon, 15 Mar 2010, Sheng Yang wrote:
> > > Hi Stefano
> > >
> > > I've checked your patches. And one point puzzled me(I am looking into
> > > pv_ops dom0 code): seems if it depends on PIRQ, it would still require to
> > > do EOI(then result in vmexit) for edge triggered interrupt? (through
> > > xen_pirq_chip->end). And unmask is still a heavy work required
> > > vmexit?(seems it need twice vmexit, even heavier than current HVM
> > > solution)
> > 
> > Only when pirq_needs_eoi(irq) returns true, and this happens when
> > PIRQ_NEEDS_EOI is set.
> > In my patch series I am making sure PIRQ_NEEDS_EOI is never set for any
> > pirq on HVM.
> > 
> OK.
> 
> I would like to work on the PIRQ porting upstream Linux(I would try ACPI but 
> not sure if it would make code much more complex, e.g. cpu hotplug, PCI 
> hotplug... A simple version would be just using PIRQ instead of VIRQ in my 
> patches, but PIRQ is flexible, I would see if I can do more with it). And we 
> may not get a version exactly the same as pv_ops dom0 code in the end... I 

That is OK. There is no problems in ripping out the dom0 code and
building on top of your code.