On Tue, Sep 19, 2017 at 03:15:44PM +0200, Cédric Le Goater wrote:
> On 09/19/2017 04:27 AM, David Gibson wrote:
> > On Mon, Sep 11, 2017 at 07:12:15PM +0200, Cédric Le Goater wrote:
> >> Start with a couple of attributes for the XIVE sPAPR controller
> >> model. The number of provisionned IRQ is necessary to size the
> >> different internal XIVE tables, the number of CPUs is also.
> >>
> >> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> >
> > [snip]
> >
> >> +static void spapr_xive_realize(DeviceState *dev, Error **errp)
> >> +{
> >> + sPAPRXive *xive = SPAPR_XIVE(dev);
> >> +
> >> + if (!xive->nr_targets) {
> >> + error_setg(errp, "Number of interrupt targets needs to be greater
> >> 0");
> >> + return;
> >> + }
> >> + /* We need to be able to allocate at least the IPIs */
> >> + if (!xive->nr_irqs || xive->nr_irqs < xive->nr_targets) {
> >> + error_setg(errp, "Number of interrupts too small");
> >> + return;
> >> + }
> >> +}
> >> +
> >> +static Property spapr_xive_properties[] = {
> >> + DEFINE_PROP_UINT32("nr-irqs", sPAPRXive, nr_irqs, 0),
> >> + DEFINE_PROP_UINT32("nr-targets", sPAPRXive, nr_targets, 0),
> >
> > I'm a bit uneasy about the number of targets having to be set in
> > advance: this can make life awkward when CPUs are hotplugged. I know
> > there's something similar in xics, but it has caused some hassles, and
> > we're starting to move away from it.
> >
> > Do you really need this?
> >
>
> Some of the internal table size depend on the number of cpus
> defined for the machine.
Which ones? My impression was that there needed to be at least #cpus
* #priority-levels EQs, but there could be more than that, so it was
no longer as tightly bound to the number if "interrupt servers" as xics.
> When the sPAPRXive object is instantiated,
> we use xics_max_server_number() to get the max number of cpus
> provisioned.
>
> C.
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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