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SubjectRe: [PATCH v3 0/6] virtio_balloon: virtio 1 support
On Wed, Apr 01, 2015 at 02:57:35PM +0200, Michael S. Tsirkin wrote:
> Virtio 1.0 doesn't include a modern balloon device. At some point we'll likely
> define an incompatible interface with a different ID and different
> semantics. But for now, it's not a big effort to support a transitional
> balloon device: this has the advantage of supporting existing drivers,
> transparently, as well as transports that don't allow mixing virtio 0 and
> virtio 1 devices. And balloon is an easy device to test, so it's also useful
> for people to test virtio core handling of transitional devices.
>
> The only interface issue is with the stats buffer, which has misaligned
> fields. We could leave it as is, but this sets a bad precedent that
> others might copy by mistake.
>
> As we need to change stats code to do byteswaps for virtio 1.0, it seems easy
> to fix by prepending a 6 byte reserved field. I also had to change config
> structure field types from __le32 to __u32 to match other devices. This means
> we need a couple of __force tags for legacy path but that seems minor.

Rusty, what are your thoughts here?
How about merging this for 4.1?


> changes from v2:
> fix up stats endian-ness
> Changes from v1:
> correctly handle config space endian-ness
>
> Michael S. Tsirkin (6):
> virtio_balloon: transitional interface
> virtio: balloon might not be a legacy device
> virtio_ccw: support non-legacy balloon devices
> virtio_mmio: support non-legacy balloon devices
> virtio_pci: support non-legacy balloon devices
> virtio: drop virtio_device_is_legacy_only
>
> include/linux/virtio.h | 2 --
> include/uapi/linux/virtio_balloon.h | 11 +++++++++--
> drivers/s390/kvm/virtio_ccw.c | 10 +++-------
> drivers/virtio/virtio.c | 6 ------
> drivers/virtio/virtio_balloon.c | 33 +++++++++++++++++++++++----------
> drivers/virtio/virtio_mmio.c | 8 --------
> drivers/virtio/virtio_pci_modern.c | 3 ---
> 7 files changed, 35 insertions(+), 38 deletions(-)
>
> --
> MST


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