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

Thomas Gleixner
2019-06-18T23:15:52Z

On Tue, 18 Jun 2019, Ricardo Neri wrote:

> 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
>