Re: In kernel PIC support: kernel patch

Dong, Eddie
2007-06-21T14:57:03Z

Gregory Haskins wrote:

> So assuming this newly enlightened position is true, I think this
> means we have a choice:
>
> 1) Drop support for mixed "level-1" mode and move the PIC to the
> kernel now as Eddie is doing
>
> 2) Keep the level-1/2 distinction, and add support for making sure
> that once a vector is acked in the PIC, it truely gets put into
> service immediately.
>
> I can think of a really simple interface for (2). All we
> really need to
> do is
>
> a) go back to synchronous injection (as previously suggested)

For level-2 support, that means no PIC/APIC in user space, it is the
device want to assert/dessert an irq line request. There is no notion
of injecting IRQ. That is why I added new APIs.
Even with level-1 in consideration, we still need these new APIs to
support level-2. A device such as kerboard could frequently assert
and dessert the irq line. A single ker strobe will see 5-10 dessert
request from device model and 1 assert request.

So new APIs are a must IMO.

thx, eddie