From: Jan Kiszka <jan.kiszka@web.de>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Anthony Perard <anthony.perard@citrix.com>,
QEMU-devel <qemu-devel@nongnu.org>,
Xen Devel <xen-devel@lists.xensource.com>,
Avi Kivity <avi@redhat.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [Qemu-devel] [PATCH V2 5/5] vga-cirrus: Workaround during restore when using Xen.
Date: Fri, 06 Jan 2012 14:50:44 -0200 [thread overview]
Message-ID: <4F072664.3070000@web.de> (raw)
In-Reply-To: <CAFEAcA-A7YujsGDpGezxeNmB9z5rG=Rtp7UHX1R5wWoL=wukwA@mail.gmail.com>
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On 2012-01-06 13:58, Peter Maydell wrote:
> On 6 January 2012 13:30, Jan Kiszka <jan.kiszka@web.de> wrote:
>> The third point indicates that there is rather more generic room for
>> improvements: Why should qemu reset device models before restore at all?
>
> Commit 5a8a49d7aa says:
> # if we load from a snapshot, the machine can be in any state. That can
> # cause troubles if loading an older image which does not carry all state
> # information the executing QEMU requires. Hardly any device takes care of
> # this scenario.
>
> I think it's also easier to reason about devices if you know that the
> device before a load was in a known clean state rather than being
> anything at all.
True, that's why we do this ATM. But issuing the reset globally without
giving devices chance to handle this more precisely is just a suboptimal
workaround, one that we may want to overcome at some point.
Jan
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WARNING: multiple messages have this Message-ID (diff)
From: Jan Kiszka <jan.kiszka@web.de>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Anthony Perard <anthony.perard@citrix.com>,
QEMU-devel <qemu-devel@nongnu.org>,
Xen Devel <xen-devel@lists.xensource.com>,
Avi Kivity <avi@redhat.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [PATCH V2 5/5] vga-cirrus: Workaround during restore when using Xen.
Date: Fri, 06 Jan 2012 14:50:44 -0200 [thread overview]
Message-ID: <4F072664.3070000@web.de> (raw)
In-Reply-To: <CAFEAcA-A7YujsGDpGezxeNmB9z5rG=Rtp7UHX1R5wWoL=wukwA@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 925 bytes --]
On 2012-01-06 13:58, Peter Maydell wrote:
> On 6 January 2012 13:30, Jan Kiszka <jan.kiszka@web.de> wrote:
>> The third point indicates that there is rather more generic room for
>> improvements: Why should qemu reset device models before restore at all?
>
> Commit 5a8a49d7aa says:
> # if we load from a snapshot, the machine can be in any state. That can
> # cause troubles if loading an older image which does not carry all state
> # information the executing QEMU requires. Hardly any device takes care of
> # this scenario.
>
> I think it's also easier to reason about devices if you know that the
> device before a load was in a known clean state rather than being
> anything at all.
True, that's why we do this ATM. But issuing the reset globally without
giving devices chance to handle this more precisely is just a suboptimal
workaround, one that we may want to overcome at some point.
Jan
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next prev parent reply other threads:[~2012-01-06 16:51 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-09 21:54 [Qemu-devel] [PATCH V2 0/5] Have a working migration with Xen Anthony PERARD
2011-12-09 21:54 ` Anthony PERARD
2011-12-09 21:54 ` [Qemu-devel] [PATCH V2 1/5] vl.c: Do not save RAM state when Xen is used Anthony PERARD
2011-12-09 21:54 ` Anthony PERARD
2011-12-15 15:12 ` [Qemu-devel] " Anthony Liguori
2011-12-15 15:12 ` Anthony Liguori
2011-12-18 17:44 ` [Qemu-devel] " Avi Kivity
2011-12-18 17:44 ` Avi Kivity
2011-12-20 16:46 ` [Qemu-devel] " Anthony PERARD
2011-12-20 16:46 ` Anthony PERARD
2011-12-09 21:54 ` [Qemu-devel] [PATCH V2 2/5] xen mapcache: Check if a memory space has moved Anthony PERARD
2011-12-09 21:54 ` Anthony PERARD
2011-12-12 12:53 ` [Qemu-devel] " Stefano Stabellini
2011-12-12 12:53 ` Stefano Stabellini
2011-12-09 21:54 ` [Qemu-devel] [PATCH V2 3/5] Introduce premigrate RunState Anthony PERARD
2011-12-09 21:54 ` Anthony PERARD
2011-12-15 15:14 ` [Qemu-devel] " Anthony Liguori
2011-12-15 15:14 ` Anthony Liguori
2011-12-15 16:31 ` [Qemu-devel] " Luiz Capitulino
2011-12-15 16:31 ` Luiz Capitulino
2011-12-19 17:27 ` [Qemu-devel] " Anthony PERARD
2011-12-19 17:27 ` Anthony PERARD
2012-01-03 19:05 ` [Qemu-devel] " Luiz Capitulino
2012-01-03 19:05 ` Luiz Capitulino
2012-01-05 12:26 ` [Qemu-devel] " Anthony PERARD
2012-01-05 12:26 ` Anthony PERARD
2011-12-09 21:54 ` [Qemu-devel] [PATCH V2 4/5] xen: Change memory access behavior during migration Anthony PERARD
2011-12-09 21:54 ` Anthony PERARD
2011-12-12 12:55 ` [Qemu-devel] " Stefano Stabellini
2011-12-12 12:55 ` Stefano Stabellini
2011-12-09 21:54 ` [Qemu-devel] [PATCH V2 5/5] vga-cirrus: Workaround during restore when using Xen Anthony PERARD
2011-12-09 21:54 ` Anthony PERARD
2011-12-10 10:45 ` [Qemu-devel] " Jan Kiszka
2011-12-10 10:45 ` Jan Kiszka
2011-12-12 13:18 ` [Qemu-devel] " Stefano Stabellini
2011-12-12 13:18 ` Stefano Stabellini
2011-12-12 14:03 ` [Qemu-devel] " Jan Kiszka
2011-12-12 14:03 ` Jan Kiszka
2011-12-12 14:41 ` [Qemu-devel] " Stefano Stabellini
2011-12-12 14:41 ` Stefano Stabellini
2011-12-12 15:03 ` [Qemu-devel] " Jan Kiszka
2011-12-12 15:03 ` Jan Kiszka
2011-12-12 15:32 ` [Qemu-devel] " Stefano Stabellini
2011-12-12 15:32 ` Stefano Stabellini
2011-12-13 11:55 ` [Qemu-devel] early_savevm (was: [PATCH V2 5/5] vga-cirrus: Workaround during restore when using Xen.) Stefano Stabellini
2011-12-13 11:55 ` Stefano Stabellini
2011-12-13 12:35 ` [Qemu-devel] early_savevm Jan Kiszka
2011-12-13 12:35 ` early_savevm Jan Kiszka
2011-12-13 13:59 ` [Qemu-devel] early_savevm Stefano Stabellini
2011-12-13 13:59 ` early_savevm Stefano Stabellini
2011-12-18 17:43 ` [Qemu-devel] early_savevm Avi Kivity
2011-12-18 17:43 ` early_savevm Avi Kivity
2012-01-11 17:55 ` [Qemu-devel] early_savevm Anthony Liguori
2011-12-18 17:41 ` [Qemu-devel] [PATCH V2 5/5] vga-cirrus: Workaround during restore when using Xen Avi Kivity
2011-12-18 17:41 ` Avi Kivity
2012-01-04 16:38 ` [Qemu-devel] " Stefano Stabellini
2012-01-04 16:38 ` Stefano Stabellini
2012-01-04 17:23 ` [Qemu-devel] " Avi Kivity
2012-01-04 17:23 ` Avi Kivity
2012-01-05 12:30 ` [Qemu-devel] " Stefano Stabellini
2012-01-05 12:30 ` Stefano Stabellini
2012-01-05 12:50 ` [Qemu-devel] " Avi Kivity
2012-01-05 12:50 ` Avi Kivity
2012-01-05 13:17 ` [Qemu-devel] " Stefano Stabellini
2012-01-05 13:17 ` Stefano Stabellini
2012-01-05 13:32 ` [Qemu-devel] " Avi Kivity
2012-01-05 13:32 ` Avi Kivity
2012-01-05 14:34 ` [Qemu-devel] " Stefano Stabellini
2012-01-05 14:34 ` Stefano Stabellini
2012-01-05 15:19 ` [Qemu-devel] " Avi Kivity
2012-01-05 15:19 ` Avi Kivity
2012-01-05 15:53 ` [Qemu-devel] " Stefano Stabellini
2012-01-05 15:53 ` Stefano Stabellini
2012-01-05 16:33 ` [Qemu-devel] " Avi Kivity
2012-01-05 16:33 ` Avi Kivity
2012-01-05 17:21 ` [Qemu-devel] " Stefano Stabellini
2012-01-05 17:21 ` Stefano Stabellini
2012-01-05 17:50 ` [Qemu-devel] " Avi Kivity
2012-01-05 17:50 ` Avi Kivity
2012-01-05 18:49 ` [Qemu-devel] " Jan Kiszka
2012-01-05 18:49 ` Jan Kiszka
2012-01-06 10:50 ` [Qemu-devel] " Stefano Stabellini
2012-01-06 10:50 ` Stefano Stabellini
2012-01-06 13:30 ` [Qemu-devel] " Jan Kiszka
2012-01-06 13:30 ` Jan Kiszka
2012-01-06 14:40 ` [Qemu-devel] " Stefano Stabellini
2012-01-06 14:40 ` Stefano Stabellini
2012-01-08 10:39 ` [Qemu-devel] " Avi Kivity
2012-01-08 10:39 ` Avi Kivity
2012-01-09 15:25 ` [Qemu-devel] " Stefano Stabellini
2012-01-09 15:25 ` Stefano Stabellini
2012-01-09 15:28 ` [Qemu-devel] " Jan Kiszka
2012-01-09 15:28 ` Jan Kiszka
2012-01-09 15:36 ` [Qemu-devel] " Avi Kivity
2012-01-09 15:36 ` Avi Kivity
2012-01-06 15:58 ` [Qemu-devel] " Peter Maydell
2012-01-06 15:58 ` Peter Maydell
2012-01-06 16:50 ` Jan Kiszka [this message]
2012-01-06 16:50 ` Jan Kiszka
2012-01-06 12:19 ` [Qemu-devel] " Avi Kivity
2012-01-06 12:19 ` Avi Kivity
2012-01-06 12:22 ` [Qemu-devel] " Jan Kiszka
2012-01-06 12:22 ` Jan Kiszka
2012-01-06 12:47 ` [Qemu-devel] " Avi Kivity
2012-01-06 12:47 ` Avi Kivity
2011-12-12 12:58 ` [Qemu-devel] " Stefano Stabellini
2011-12-12 12:58 ` Stefano Stabellini
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