Re: [Qemu-devel] [PATCH 00/13] virtio migration: Flip outer layer to vmstate

[Cornelia Huck]

On Tue, 21 Jun 2016 20:13:54 +0100
"Dr. David Alan Gilbert (git)" <address@hidden> wrote:

> From: "Dr. David Alan Gilbert" <address@hidden>
> 
> Hi,
>   This series converts the outer most layer of virtio to
> use VMState macros;  this is the easy bit, but I'm hoping that
> having done that, the next trick is to nibble away at the virtio_save/load
> functions and all of the zillions of device/bus helpers.
> 
> I think the first two patches are the most controversial;
> they remove migration support for old version of virtio-net and virtio-serial;
> (for virtio-net versions prior to 0.11 and for virtio-serial prior to 0.13).

These seem rather ancient and we would not care from a s390x
perspective. Others may think differently, though...

> I'm working on the basis that migration has bit rotted enough so
> that the streams aren't migration compatible for that long back
> on upstream - but if anyone knows otherwise please shout.
> 
> The reason for doing those is that the virtio structure makes
> it a bit tricky to pass the outer device version number down
> through VMState to the device specific code (I can do it
> as a hack if necessary using a dummy is_needed function);
> and with -net and -serial compatibility sorted I think
> every other device just supports a single version.
> 
> My main reason for doing this is to get rid of the
> calls to register_savevm ('going to disappear as soon..' since 2010)

Real Soon Now :) Thank you for tackling virtio!

> 
> It's lightly tested using the magic line:
> ./x86_64-softmmu/qemu-system-x86_64 -nographic -machine 
> pc-i440fx-2.6,accel=kvm -cpu qemu64 -m 2048M -drive 
> file=/home/vmimages/f20.img,if=none,id=drivea -device virtio-scsi,id=scsi 
> -device scsi-hd,drive=drivea -device virtio-rng -device virtio-serial 
> -chardev file,id=test,path=/tmp/testfile -device 
> virtconsole,chardev=test,name=foo -virtfs 
> local,path=/home,security_model=passthrough,mount_tag=host_share  -device 
> virtio-gpu  -drive file=/home/vmimages/jeos-19-64.qcow2,id=jeos,if=none 
> -device virtio-blk,drive=jeos  -device virtio-balloon
> 
> Thoughts?

Do you have a git tree to test somewhere? I'll take a look at the
patches later, but it would be good if we could give it a quick test on
s390x as well.