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From: Ronen Hod <rhod@redhat.com>
To: Marcel Apfelbaum <marcel.a@redhat.com>
Cc: aliguori@us.ibm.com, gleb@redhat.com, mst@redhat.com,
	hutao@cn.fujitsu.com, qemu-devel@nongnu.org, kraxel@redhat.com,
	pbonzini@redhat.com, afaerber@suse.de, vrozenfe@redhat.com
Subject: Re: [Qemu-devel] [PATCH for-1.6 V2 0/2] pvpanic: Separate pvpanic from machine type
Date: Wed, 14 Aug 2013 10:02:37 +0300	[thread overview]
Message-ID: <520B2B8D.8070401@redhat.com> (raw)
In-Reply-To: <1376233843-19410-1-git-send-email-marcel.a@redhat.com>

How about adding a flag that tells QEMU whether to pause or reboot the guest
after the panic?
We cannot assume that we always have a management layer that takes care
of this.
One example is Microsoft's WHQL that deliberately generates a BSOD, and then
examines the dump files.

Ronen.

On 08/11/2013 06:10 PM, Marcel Apfelbaum wrote:
> Creating the pvpanic device as part of the machine type has the
> potential to trigger guest OS, guest firmware and driver bugs.
> The potential of such was originally viewed as minimal.
> However, since releasing 1.5 with pvpanic as part
> of the builtin machine type, several issues were observed
> in the field:
>   - Some Windows versions triggered 'New Hardware Wizard' and
>     an unidentified device appeared in Device Manager.
>   - Issue reported off list: on Linux >= 3.10
>     the pvpanic driver breaks the reset on crash option:
>     VM stops instead of being reset.
>
> pvpanic device also changes monitor command behaviour in some cases,
> such silent incompatible changes aren't expected by management tools:
>   - Monitor command requires 'cont' before 'system_reset'
>     in order to restart the VM after kernel panic/BSOD
>
> Note that libvirt is the main user and libvirt people indicated their
> preference to creating device with -device pvpanic rather than a
> built-in one that can't be removed.
>
> These issues were raised at last KVM call. The agreement reached
> there was that we were a bit too rash to make the device
> a builtin, and that for 1.6 we should drop the pvpanic device from the
> default machine type, instead teach management tools to add it by
> default using -device pvpanic.
> It's not clear whether changing 1.5 behaviour at this point
> is a sane thing, so this patchset doesn't touch 1.5 machine type.
>
> This patch series reworks the patchset from Hu Tao
> (don't create pvpanic device by default)
> addressing comments and modifying behaviour according
> to what was discussed on the call.
> Please review and consider for 1.6.
>
> A related discussion can be followed at
> http://lists.nongnu.org/archive/html/qemu-devel/2013-08/msg00036.html.
>
> This is a continuation of patches sent by Hu Tao:
> http://lists.nongnu.org/archive/html/qemu-devel/2013-08/msg00124.html
> http://lists.nongnu.org/archive/html/qemu-devel/2013-08/msg00125.html
>
> Changes from v1 (by Hu Tao):
>   - Keep pvpanic device enabled by default for 1.5
>     for backport compatibility
>   - Addressed Andreas Färber review (removed bus type)
>   - Small changes to be posible to enable pvpanic
>     both from command line and from machine_init
>   - Added pvpanic to MISC category
>
> Marcel Apfelbaum (2):
>    hw/misc: don't create pvpanic device by default
>    hw/misc: make pvpanic known to user
>
>   hw/i386/pc_piix.c |  9 ++++-----
>   hw/i386/pc_q35.c  |  7 ++++---
>   hw/misc/pvpanic.c | 25 ++++++++++---------------
>   3 files changed, 18 insertions(+), 23 deletions(-)
>

  parent reply	other threads:[~2013-08-14  7:03 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-11 15:10 [Qemu-devel] [PATCH for-1.6 V2 0/2] pvpanic: Separate pvpanic from machine type Marcel Apfelbaum
2013-08-11 15:10 ` [Qemu-devel] [PATCH for-1.6 V2 1/2] hw/misc: don't create pvpanic device by default Marcel Apfelbaum
2013-08-12  3:06   ` Hu Tao
2013-08-12 15:59   ` Andreas Färber
2013-08-13 11:26   ` Markus Armbruster
2013-08-11 15:10 ` [Qemu-devel] [PATCH for-1.6 V2 2/2] hw/misc: make pvpanic known to user Marcel Apfelbaum
2013-08-12  3:07   ` Hu Tao
2013-08-12 15:53 ` [Qemu-devel] [PATCH for-1.6 V2 0/2] pvpanic: Separate pvpanic from machine type Eric Blake
2013-08-12 16:26   ` Marcel Apfelbaum
2013-08-14  7:02 ` Ronen Hod [this message]
2013-08-21  8:03   ` Marcel Apfelbaum
2013-08-21  8:18     ` Paolo Bonzini
2013-08-21  9:42       ` Michael S. Tsirkin
2013-08-21  9:56         ` Hu Tao
2013-08-21  9:59         ` Paolo Bonzini
2013-08-21 10:16           ` Michael S. Tsirkin
2013-08-21 10:37             ` Paolo Bonzini
2013-08-14 16:27 ` Anthony Liguori

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