On 02/07/2011 01:53 PM, Michael S. Tsirkin wrote:
On Mon, Feb 07, 2011 at 01:33:57PM -0600, Anthony Liguori wrote:
On 02/07/2011 10:07 AM, Michael S. Tsirkin wrote:
New thread stated intentionally, the original patch is Message-ID:
<349e93a4cfc6e1effc1b681cae53f805fdb9624e.1296713825.git.amit.s...@redhat.com>
On Thu, Feb 03, 2011 at 11:47:08AM +0530, Amit Shah wrote:
Add a compat property for older machine types. When this is used (via
-M pc-0.13, for example), the new flow control mechanisms will not be
used. This is done to keep migration from a machine started with older
type on a pc-0.14+ qemu to an older machine working.
The property is named 'flow_control' and defaults to on.
Reported-by: Alex Williamson<alex.william...@redhat.com>
Signed-off-by: Amit Shah<amit.s...@redhat.com>
So, I think there are two things that need to be agreed on:
- Can we commit to support migration from new qemu version to an old one?
We haven't in the past but downstreams do want this,
so it makes sense to have the infrastructure upstream.
Only within a stable release series and only when it's possible
without sacrificing integrity. I know some downstreams disagree
with this but I don't think this is a business we want to get into.
Regards,
Anthony Liguori
- The infrastructure/command line option for such support.
We have the -M flags to describe the machine that
we are running, but that abstracts away guest-visible machine,
which the migration format is not.
Also, same qemu could migrate to any older version.
So I think we would have to add a flag (call it -V for now)
to savevm/migrate commands to specify the format to be used.
Naturally some machines would be incompatible with
specific -V values, that's nothing new.
Pls comment.
OK, assuming we want this, let's talk about implementation.
I think that spreading custom flags all over the code like
this patch does would be pretty bad.
What I'd like to see is a way to
- map stable versions (e.g. machine type if we are going
to tie to that) to savevm format using
some kind of table
- for save callbacks to be able to figure out what
version to use
Why doesn't subsections already solve this problem?
Regards,
Anthony Liguori