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

[Gleb Natapov <gleb@redhat.com>]

On Sun, May 30, 2010 at 08:21:30PM +0000, Blue Swirl wrote:
> On Sun, May 30, 2010 at 8:07 PM, Gleb Natapov <gleb@redhat.com> wrote:
> > On Sun, May 30, 2010 at 07:37:59PM +0000, Blue Swirl wrote:
> >> On Sun, May 30, 2010 at 1:49 PM, Gleb Natapov <gleb@redhat.com> wrote:
> >> > On Sun, May 30, 2010 at 12:56:26PM +0000, Blue Swirl wrote:
> >> >> >> Well, I'd like to get the test program also trigger it. Now I'm getting:
> >> >> >> apic: write: 00000350 = 00000000
> >> >> >> apic: apic_reset_irq_delivered: old coalescing 0
> >> >> >> apic: apic_local_deliver: vector 3 delivery mode 0
> >> >> >> apic: apic_set_irq: coalescing 1
> >> >> >> apic: apic_get_irq_delivered: returning coalescing 1
> >> >> >> apic: apic_reset_irq_delivered: old coalescing 1
> >> >> >> apic: apic_local_deliver: vector 3 delivery mode 0
> >> >> >> apic: apic_set_irq: coalescing 0
> >> >> >> apic: apic_get_irq_delivered: returning coalescing 0
> >> >> >> apic: apic_reset_irq_delivered: old coalescing 0
> >> >> >> apic: apic_local_deliver: vector 3 delivery mode 0
> >> >> >> apic: apic_set_irq: coalescing 0
> >> >> >>
> >> > So interrupt is _alway_ coalesced. If apic_get_irq_delivered() returns
> >> > 0 it means the interrupt was not delivered.
> >>
> >> That seems strange. I changed the program so that the handler gets
> >> executed, also output a dot to serial from the handler. I changed the
> >> frequency to 2Hz.
> >>
> >> Now, if I leave out -rtc-td-hack, I get the dots at 2Hz as expected.
> >> With -rtc-td-hack, the dots come out much faster. I added
> >> DEBUG_COALESCING also to RTC, with that enabled I get:
> >> qemu -L . -bios coalescing.bin -d in_asm,int -no-hpet -rtc-td-hack -serial stdio
> >> cmos: coalesced irqs scaled to 0
> >> cmos: coalesced irqs increased to 1
> >> cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> .cmos: injecting on ack
> >> ..cmos: injecting from timer
> >> .cmos: coalesced irqs increased to 2
> >> cmos: injecting on ack
> >>
> >> So, there are bogus injections.
> >
> > Looks like irr in apic is never cleared. Probably bug in userspace apic
> > emulation. I'll look into it. Try to route interrupt via APIC (not ExtInt),
> > or use qemu-kvm with in kernel irq chip.
> 
> With APIC you mean Fixed? Then the IRQ is not delivered at all.
You need to deliver it through IOAPIC.

--
			Gleb.