Re: [Xen-devel] [PATCH 3/5] xen/arm: Don't reinject the IRQ if it's already in LRs

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-06-25 at 17:36 +0100, Stefano Stabellini wrote:
> I think it's time we introduce a "status" member in struct irq_desc, so
> that we are not dependent on the information in the GICH_LR registers or
> the queue a pending_irq has been added to.

Yes please, I find this one of the hardest things to keep straight in my
head (not helped by my inability to remember which of pending and
inflight is which...)

> I would implement it as a bitfield:
> 
> int status;
> #define GIC_IRQ_ENABLED  (1<<0)
> #define GIC_IRQ_INFLIGHT (1<<1)
> #define GIC_IRQ_INLR     (1<<2)
> 
> This way you should just go through the inflight queue and check whether
> status & GIC_IRQ_INLR.

Since some of this stuff happens in interrupt context you probably want
test_bit/set_bit et al rather than regular boolean logic, don't you?

> At the moment we just want to represent this basic state machine:
> 
> irq guest asserted -> inflight -> injected (inlr) -> unasserted (maintenance 
> interrupt)

Can we model the states after the active/pending states which the gic
has? It might make a bunch of stuff clearer?

Ian.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel