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Date: Tue, 3 Apr 2012 16:51:06 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCHv3] piix: fix up/down races
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To: Alex Williamson <alex.williamson@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, gleb@redhat.com, qemu-devel@nongnu.org, Isaku Yamahata <yamahata@valinux.co.jp>, Gerd Hoffmann <kraxel@redhat.com>, imammedo@redhat.com, Paolo Bonzini <pbonzini@redhat.com>, Aurelien Jarno <aurelien@aurel32.net>

On Tue, Apr 03, 2012 at 03:56:18PM +0300, Michael S. Tsirkin wrote:
> > > +    /*
> > > +     * Clear DOWN register - this is good for a case where guest can't
> > > +     * write to CLR_DOWN because of VM reset, and for compatibility with
> > > +     * old guests which do not have CLR_DOWN.
> > > +     */
> > > +    s->pci0_status.down &= ~(1U << slot);
> > 
> > Should we clear "up" here too?
> 
> On eject clearing "up" is probably OK. However I'm not sure
> what purpose would it serve, and it seems the less hacks we do the
> better.

I added a comment to clarify this.