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Message-ID: <1810739463.3115068.1362563297384.JavaMail.root@redhat.com>
Date: Wed, 6 Mar 2013 04:48:17 -0500 (EST)
From: Paolo Bonzini <pbonzini@...hat.com>
To: Gleb Natapov <gleb@...hat.com>
Cc: Hu Tao <hutao@...fujitsu.com>,
Peter Maydell <peter.maydell@...aro.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jan Kiszka <jan.kiszka@...mens.com>,
qemu-devel <qemu-devel@...gnu.org>,
Markus Armbruster <armbru@...hat.com>,
Blue Swirl <blauwirbel@...il.com>,
Orit Wasserman <owasserm@...hat.com>,
kvm list <kvm@...r.kernel.org>,
Juan Quintela <quintela@...hat.com>,
Alexander Graf <agraf@...e.de>,
Andrew Jones <drjones@...hat.com>,
Alex Williamson <alex.williamson@...hat.com>,
Sasha Levin <levinsasha928@...il.com>,
Stefan Hajnoczi <stefanha@...hat.com>,
Luiz Capitulino <lcapitulino@...hat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Kevin Wolf <kwolf@...hat.com>,
Anthony Liguori <aliguori@...ibm.com>,
Marcelo Tosatti <mtosatti@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v13 0/8] pv event interface between host and guest
> On Wed, Mar 06, 2013 at 10:07:31AM +0100, Paolo Bonzini wrote:
> > Il 06/03/2013 09:56, Hu Tao ha scritto:
> > >> >
> > >> > Something like this should work (in SeaBIOS's
> > >> > src/acpi-dsdt-isa.dsl):
> > >> >
> > >> > Device(PEVT) {
> > >> > Name(_HID, EisaId("QEMU0001"))
> > >> > OperationRegion(PEOR, SystemIO, 0x505, 0x01)
> > >> > Field(PEOR, ByteAcc, NoLock, Preserve) {
> > >> > PEPT, 8,
> > >> > }
> > >> >
> > >> > Method(_STA, 0, NotSerialized) {
> > >> > Store(PEPT, Local0)
> > >> > If (LEqual(Local0, Zero)) {
> > >> > Return (0x00)
> > >> > } Else {
> > >> > Return (0x0F)
> > >> > }
> > >> > }
> > > IIUC, here _STA reads from ioport 0x505, if the result is 0, then the
> > > device is not present. Otherwise, the device is present. But as Gleb
> > > said, ''the data you read from unassigned port is not guarantied to be
> > > zero, it may depend on QEMU version''. What should I do to tell if the
> > > device is present or not correctly?
> >
> > The firmware is tied to the QEMU version, so you can rely on
> > unassigned ports returning zero.
> >
> > Later we can change this to use fw-cfg.
>
> I thought we agreed to do it from the start :)
Then Hu will need to patch the _STA method.
Paolo
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