Re: [Qemu-devel] [PATCH 11/22] i8259: Update IRQ state after reset

[Blue Swirl]

On Sun, Oct 2, 2011 at 8:41 PM, Avi Kivity <address@hidden> wrote:
>> >
>> >
>> > Would not this corruption also happen on real hardware?  If reset
>> > to the disk controller is delayed by a slow gate or extra
>> > capacitance on a line?
>>
>> Maybe, but the delays are probably too short on real HW before any
>> packets are sent or disk gets written. On QEMU, I/O can be
>> instantaneous.
>>
>
> Right, this is a real difference.  If any hardware actually depends on this, 
> we can model it by launching a timer instead of issuing the I/O.  When the 
> reset arrives to the disk controller, it will cancel the timer.
>
> This is expensive both to code and in run-time performance, but we can afford 
> the expense since we don't have such a case, yes?

It's already in, see -win2k-hack and floppy DMA hack.