[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH] Change virtio-console to PCI_CLASS_SERIAL_OTHER

From: Anthony Liguori
Subject: Re: [Qemu-devel] [PATCH] Change virtio-console to PCI_CLASS_SERIAL_OTHER
Date: Wed, 27 May 2009 17:37:52 -0500
User-agent: Thunderbird (X11/20090409)

Mark McLoughlin wrote:
On Wed, 2009-05-27 at 09:21 -0500, Anthony Liguori wrote:

We need a mechanism to toggle this for both this and virtio-blk. The reason a toggle is needed is so that 0.11 can create the same device model as 0.10.

Okay, so the scenario is:

  - 0.10 guest running on source machine

  - migrate to dest machine running 0.11

  - the device model cannot change or the guest OS will get confused

Correct, but in this case, the problem is when you shutdown and start up the VM again. In the process, it may trigger something like a driver reinstallation or worse, reactivation. It's necessary to be able to prevent this by creating exactly the same device model that was previously created.

This is can't really be a hard rule yet without the machine config, but we should do our best when we can.

How about running qemu on the dest machine with -model-version=0.10 ?

Linear versioning is a bit too fickle esp due to distro backporting.

Nasty thing about it is that the distributions couldn't cherry-pick
changes like this because they'd deviate from the device model contract
for a given upstream version.

Could we not put this stuff in savevm and change the device model

It's shutdown/restart that's the problem. Windows uses a lot of different information to calculate whether activation is required again and even small changes can end up pushing things over the edge.


Anthony Liguori


reply via email to

[Prev in Thread] Current Thread [Next in Thread]