Re: [PATCH] 2.6.18-rt7: PowerPC: fix breakage in threaded fasteoi type IRQ handlers

Ingo Molnar
2006-11-20T17:28:04Z

* Sergei Shtylyov <sshtylyov@ru.mvista.com> wrote:

> Hello.
>
> Ingo Molnar wrote:
>
> >>>on PPC64, 'get the vector' initiates an ACK as well - is that done
> >>>before handle_irq() is done?
>
> >> Exactly. How else do_IRQ() would know the vector?
>
> >the reason i'm asking is that in this case masking is a bit late at this
> >point and there's a chance for a repeat interrupt.
>
> How's that? Acknowledge != EOI on OpenPIC (as well as 8259).
> Acknoledging sets the bit in the in-service register preventing all
> the interrupts with same or lower prioriry from being accepted.

ah, ok. The x86 APIC does that automatically, and only an EOI has to be
passed. So i guess we are in wild agreement ;)

i'm hacking up something now to see whether it makes sense to introduce
a central threaded flow type, or whether it's better the branch off the
current flow types (as the code does it right now).

Ingo