Re: [RFC PATCH v4 18/21] x86/apic: Add a parameter for the APIC delivery mode

Ricardo Neri
2019-06-18T22:48:02Z

On Sun, Jun 16, 2019 at 11:55:03AM +0200, Thomas Gleixner wrote:
> On Thu, 23 May 2019, Ricardo Neri wrote:
> >
> > struct irq_cfg {
> > - unsigned int dest_apicid;
> > - unsigned int vector;
> > + unsigned int dest_apicid;
> > + unsigned int vector;
> > + enum ioapic_irq_destination_types delivery_mode;
>
> And how is this related to IOAPIC?

In my view, IOAPICs can also be programmed with a delivery mode. Mode
values are the same for MSI interrupts.

> I know this enum exists already, but in
> connection with MSI this does not make any sense at all.

Is the issue here the name of the enumeration?

>
> > +
> > + /*
> > + * Initialize the delivery mode of this irq to match the
> > + * default delivery mode of the APIC. This is useful for
> > + * children irq domains which want to take the delivery
> > + * mode from the individual irq configuration rather
> > + * than from the APIC.
> > + */
> > + apicd->hw_irq_cfg.delivery_mode = apic->irq_delivery_mode;
>
> And here it's initialized from apic->irq_delivery_mode, which is an
> u32. Intuitive and consistent - NOT!

Yes, this is wrong. Then should the member in the structure above be an
u32 instead of enum ioapic_irq_destination_types?

Thanks and BR,
Ricardo