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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] Register uhci_reset() callback.
Date: Tue, 16 Jun 2009 17:54:54 +0100
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To: Gleb Natapov <gleb@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, qemu-devel@nongnu.org, Avi Kivity <avi@redhat.com>

On Tuesday 16 June 2009, Gleb Natapov wrote:
> On Tue, Jun 16, 2009 at 06:14:51PM +0300, Blue Swirl wrote:
> > > Because interrupt line is stuck a guest can't get to the point where it
> > >  loads a driver to the second device. For outside observer the guest
> > >  just hangs.
> >
> > I see. The problem is in piix_pci interrupt handling, pci_irq_levels[]
> > should be set to zero on reset.
>
> The patch that does that was rejected earlier :)
> http://lists.gnu.org/archive/html/qemu-devel/2009-06/msg00342.html
> http://lists.gnu.org/archive/html/qemu-devel/2009-06/msg00344.html

You're both wrong.

If allow devices to be reset independently then they should probably set theit 
IRQ output on reset.

IRQ muxes (e.g. PCI busses) should handle reseting and save/restore of their 
own internal state.

Devices should not cause IRQ state changes on restore. Commit 3dcd219f is 
incorrect.

Paul