[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC 0/4] virtio: stabilize migration format
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [RFC 0/4] virtio: stabilize migration format |
Date: |
Tue, 11 Dec 2012 10:02:10 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Dec 10, 2012 at 08:29:46AM -0600, Anthony Liguori wrote:
> This series replaces:
>
> qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
>
> With code that properly saves out each element of the structure using
> a well defined endian format. Migration is broken today from big endian to
> little endian hosts.
>
> There's no way to fix this problem without bumping the migration version
> number and that's exactly what we do here. By bumping the migration version
> number, we do break new->old migration but that's unavoidable right now.
>
> In order to support old->new, we assume that all incoming data is in little
> endian. The final patch adds a check to the load routines to fail old->new
> on big endian hosts where this may not have been true.
Is there a way to detect the endianness of the source host - by peaking
at a known multibyte value in the incoming stream?
That way we could even support cross-endian migration.
Not sure if this much magic makes sense since cross-endian migration is
probably used rarely.
Stefan
- Re: [Qemu-devel] [PATCH 3/4] virtio: modify savevm to have a stable wire format, (continued)
[Qemu-devel] [PATCH 2/4] virtio: add wrapper for saving/restoring virtqueue elements, Anthony Liguori, 2012/12/10
[Qemu-devel] [PATCH 1/4] savevm: introduce little endian variants of savevm routines, Anthony Liguori, 2012/12/10
[Qemu-devel] [PATCH 4/4] virtio: bump migration version number, Anthony Liguori, 2012/12/10
Re: [Qemu-devel] [RFC 0/4] virtio: stabilize migration format,
Stefan Hajnoczi <=