From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=40079 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1OqRR3-0002k9-CZ
	for qemu-devel@nongnu.org; Tue, 31 Aug 2010 10:03:40 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69)
	(envelope-from <gleb@redhat.com>) id 1OqRR0-00061w-Km
	for qemu-devel@nongnu.org; Tue, 31 Aug 2010 10:03:36 -0400
Received: from mx1.redhat.com ([209.132.183.28]:56868)
	by eggs.gnu.org with esmtp (Exim 4.69)
	(envelope-from <gleb@redhat.com>) id 1OqRR0-00061T-82
	for qemu-devel@nongnu.org; Tue, 31 Aug 2010 10:03:34 -0400
Date: Tue, 31 Aug 2010 17:03:29 +0300
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] Re: [PATCH 5/5] RFC: distinguish warm reset from
	cold reset.
Message-ID: <20100831140329.GJ10499@redhat.com>
References: <20100831025808.GA19374@valinux.co.jp>
	<4C7CFEC1.8040204@codemonkey.ws>
	<20100831131449.GG10499@redhat.com>
	<4C7D01B3.4030602@codemonkey.ws>
	<20100831132158.GH10499@redhat.com>
	<4C7D02FB.4030706@codemonkey.ws> <4C7D03C7.9090406@redhat.com>
	<4C7D04E4.2060305@codemonkey.ws> <4C7D07B9.4090909@redhat.com>
	<4C7D0A6E.8000302@codemonkey.ws>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4C7D0A6E.8000302@codemonkey.ws>
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: glommer@redhat.com, qemu-devel@nongnu.org, blauwirbel@gmail.com, Isaku Yamahata <yamahata@valinux.co.jp>, alex.williamson@redhat.com, Avi Kivity <avi@redhat.com>

On Tue, Aug 31, 2010 at 08:58:06AM -0500, Anthony Liguori wrote:
> On 08/31/2010 08:46 AM, Avi Kivity wrote:
> > On 08/31/2010 04:34 PM, Anthony Liguori wrote:
> >>On 08/31/2010 08:29 AM, Avi Kivity wrote:
> >>>Note, for most devices there's no difference.  x86 has INIT
> >>>and RESET, with the keyboard controller RESET signal sometimes
> >>>wired to INIT, and RAM doesn't have RESET.  Otherwise most
> >>>devices don't see a difference.
> >>
> >>Yes, that's why I'm wondering if we can just get away with using
> >>a simple reset() callback and for the handful of devices that
> >>don't do a full reset, they can just move the state unaffected
> >>by warm reset to ->init().
> >>
> >
> >This seems reasonable.
> 
> But I'm still not sure whether the reset signal can be deliver based
> on a pre-order transversal or whether a custom transversal was
> required that each bus participates in.
> 
The thing is in qemu reset of one device can affect state of other
device. Think about device that updates its interrupt line during reset
and this affects pic/ioapic/apic. Real HW does not have a problem that
we have here.

--
			Gleb.