Messages in this thread | | | From | (Eric W. Biederman) | Date | Wed, 10 Sep 2008 13:07:27 -0700 | Subject | Re: TARGET_CPUS in assign_irq_vector |
| |
Jeremy Fitzhardinge <jeremy@goop.org> writes:
> Hm. That would work OK for fully paravirtualized domains, which have no > direct access to real hardware in any form (well, there's pci > passthough, but interrupts are all thoroughly massaged into event channels). > > But for dom0, the kernel handles interrupts weird hybrid mode. The > interrupts themselves are delivered via event channels rather than via a > local apic, but the IO APIC is still under the kernel's control, and is > responsible for poking (Xen-allocated) vectors into it. This only > applies to physical irq event channels; there's no need to have vectors > for purely software event channels like interdomain, IPI and timers. > This is further complicated by the fact that the dom0 kernel parses the > ACPI and MPTABLES to find out about IO APICs, so the existing APIC > subsystem is already involved. I need to work out how'd I'd hook all > this together with a minimum of mess.
In that case. Having the information on the event channel tell you which cpu and which vector were received is sufficient. Then you can call into do_IRQ() with the information. Unless ack_irq() and friends are enough different at the local apic level to cause a challenge.
For the reset of the event channel interrupts you simply want to dispatch the irq directly.
Eric
| |