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Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset |
Date: |
Sun, 02 Oct 2011 16:14:46 -0400 (EDT) |
> >
> > Say the target device's output has an AND connecting #RESET and an
> > input, to the output. When #RESET is asserted, the input is
> > driven low. The output is connected to a counter.
> >
> > When #RESET is asserted, the source device's A and B are raised
> > high, with delay Da and Db. If they are different, the XNOR gate
> > generates a pulse with delay Dx. If Dx is smaller than the AND
> > gate's delay Drm, then the counter will count.
>
> On a real device, the reset and clocks are the few global signals
> available, distributed to most places. The counter would be
> constructed of JK flip flops and the reset line would be connected to
> the clear line of the flip flops. Then the counters don't count while
> reset is active.
>
>
You could have a momentary count if the RESET input's gate delay to the counter
is slower than the other inputs. It would be cleared immediately afterwards
(when phase 1 sweeps into the counter as well).
What I'm saying is that RESET order isn't defined on real hardware either, due
to signal propagation effects.
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, (continued)
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset,
Avi Kivity <=
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Avi Kivity, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset, Blue Swirl, 2011/10/02