Re: [Qemu-devel] [RFT][PATCH 07/15] qemu_irq: Add IRQ handlers with delivery feedback

[Gleb Natapov]

On Mon, May 24, 2010 at 10:13:40PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <address@hidden>
> 
> This allows to communicate potential IRQ coalescing during delivery from
> the sink back to the source. Targets that support IRQ coalescing
> workarounds need to register handlers that return the appropriate
> QEMU_IRQ_* code, and they have to propergate the code across all IRQ
> redirections. If the IRQ source receives a QEMU_IRQ_COALESCED, it can
> apply its workaround. If multiple sinks exist, the source may only
> consider an IRQ coalesced if all other sinks either report
> QEMU_IRQ_COALESCED as well or QEMU_IRQ_MASKED.
> 
Well, almost two years passed since this approach was proposed first
time[1] ;). Back then it generated bunch of nonsensical comments about
real hardware not working this way, so the hack that we have now was
introduce to overcome this resistance. I hope enough time passed for
people to gain some sense and the approach will be adopted this time.
Really this should have been done two year ago.

[1] http://lists.nongnu.org/archive/html/qemu-devel/2008-06/msg00757.html

--
                        Gleb.