Re: [Xen-devel] [RFC PATCH v2 13/22] xen/arm: its: Add virtual ITS command support

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 04/05/2015 13:58, Vijay Kilari wrote:
> On Thu, Apr 30, 2015 at 7:59 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> > Hi,
> >
> > On 30/04/15 14:47, Stefano Stabellini wrote:
> > > > > > If the devid is not within this range, the ITS won't recognize the value and
> > > > > > won't be able to send the interrupt.
> > > > > >
> > > > > > So this is clearly not the right value.
> > > > > Sure, in that case the maximum value allowed by GITS_TYPER.Devbits.
> > > > > Vijay, what is the value of GITS_TYPER.Devbits on your platform?
> > > > It is 21 bits
> > > I would imagine that 21 bits would be plenty to find an unused devid.
> > >
> > > Alternatively we could use an inexistent function of a real device, such
> > > as 00:00.1 (function 1 of the host bridge).
> > As discussed IRL, this idea sounds good to me.
> >
> > Although I would be happy with any other way which ensure the devid is free.
> Has prototyped with 00.00.1 as device id. But I see that Dom0 boot is
> slow compared to polling mode. This could be because Dom0 has to keep
> trapping on creader to check if creader is updated or not.
How did you implement the interrupt mode? Could it be improve?

Regards,

--
Julien Grall

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