Re: [Qemu-devel] [PATCH v5 2/5] hpet: entitle more irq pins for hpet

[Michael S. Tsirkin]

On Wed, Oct 09, 2013 at 11:27:24AM +0800, liu ping fan wrote:
> On Mon, Sep 30, 2013 at 11:58 PM, Michael S. Tsirkin <address@hidden> wrote:
> > On Mon, Sep 30, 2013 at 05:48:03PM +0200, Paolo Bonzini wrote:
> >> Il 30/09/2013 11:30, Michael S. Tsirkin ha scritto:
> >> > I was really only talking about q35 here.
> >> > I thought it's ugly that users can control intcap
> >> > directly. Can object_set_property be used after
> >> > qdev_try_create?
> >>
> >> Yes, after that and before qdev_init.  This is how Ping Fan is doing
> >> PIIX right now.
> >>
> >> > PIIX has another issue:
> >> > the default value in hpet is really Q35 specific,
> >> > that's also kind of ugly, isn't it?
> >>
> >> Yeah, perhaps it is.  So are you suggesting the default to be 4 (GSI2 
> >> only)?
> >>
> >> Paolo
> >
> > I suggest it fails unless caller set the property.
> >
> Sorry, out of office for a long time, and did not keep up with this
> thread in time.
> When letting the caller set the intcap, we should consider the
> compatibility of q35. For pc-q35-1.7 or later, the caller should set
> the property, otherwise not.

Set it always - just set it to a compatible value for 1.6.

> But how can the caller tell that it runs
> on q35-1.7?
> The essential problem is that "set the property" will always overwrite
> the property which is set up by compatible mechanism. So it is hard to
> implement without breaking the current mechanism. Do you think so?
> 
> Thanks and regards,
> Ping fan

Not that hard.  Fail init if it wasn't set.