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Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset
From: |
Blue Swirl |
Subject: |
Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset |
Date: |
Sun, 2 Oct 2011 20:18:38 +0000 |
On Sun, Oct 2, 2011 at 8:14 PM, Avi Kivity <address@hidden> wrote:
>> >
>> > 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.
Yes, but there the millions of reset cycles help immensely to suppress
the 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, 2011/10/02
- Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset,
Blue Swirl <=
- 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