Re: [RFC] VIRTIO_F_IO_BARRIER: use I/O barriers in driver

[Paolo Bonzini <pbonzini@redhat.com>]

On 25/04/2018 10:23, Tiwei Bie wrote:
> There will be hardware virtio devices in the future, which
> require drivers to use the barriers suitable for I/O device,
> compared with software virtio devices which just require
> drivers to use the barriers suitable for CPU core.
> 
> To fix the ordering issue for hardware virtio devices, add
> a new feature: VIRTIO_F_IO_BARRIER. When negotiated, driver
> will use the barriers suitable for I/O device.

Unfortunately this doesn't work as mentioned earlier.  Virtio live
migration assumes that features are safe if you have them on the
destination but not on the source; this feature however works the
opposite way.

Paolo