On Thu, Jan 31, 2019 at 11:43:07AM -0500, Michael S. Tsirkin wrote:
> On Thu, Jan 31, 2019 at 04:50:46PM +0100, Stefano Garzarella wrote:
> > On Thu, Jan 31, 2019 at 03:40:38PM +0000, Dr. David Alan Gilbert wrote:
> > > * Stefano Garzarella (sgarz...@redhat.com) wrote:
> > > > In order to avoid migration issues, we enable DISCARD and
> > > > WRITE ZEROES features only for machine type >= 4.0
> > > >
> > > > Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> > > > Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> > > > ---
> > > > hw/block/virtio-blk.c | 2 ++
> > > > hw/core/machine.c | 1 +
> > > > include/hw/virtio/virtio-blk.h | 1 +
> > > > 3 files changed, 4 insertions(+)
> > > >
> > > > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> > > > index 8a6754d9a2..542ec52536 100644
> > > > --- a/hw/block/virtio-blk.c
> > > > +++ b/hw/block/virtio-blk.c
> > > > @@ -1026,6 +1026,8 @@ static Property virtio_blk_properties[] = {
> > > > DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size,
> > > > 128),
> > > > DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread,
> > > > TYPE_IOTHREAD,
> > > > IOThread *),
> > > > + DEFINE_PROP_BIT("discard-wzeroes", VirtIOBlock,
> > > > conf.discard_wzeroes, 0,
> > > > + true),
> > >
> > > I think that's OK, but do you really want a DEFINE_PROP_BOOL and
> > > a bool discard_wzeroes?
> > > I think DEFINE_PROP_BIT is mostly used for a flag word where each
> > > property is one more bit in the field.
> > >
> > > Dave
> > >
> >
> > Hi Dave,
> > I was in doubt if to use DEFINE_PROP_BIT or DEFINE_PROP_BOOL, but
> > looking in the virtio-blk.c, I found that also other boolean like
> > "config-wce", "scsi", and "request-merging" was defined with
> > DEFINE_PROP_BIT, so I followed this trand.
> >
> > But I agree with you, DEFINE_PROP_BOOL should be better, so I will change
> > it!
> >
> > Thanks,
> > Stefano
>
> I wonder why doesn't virtio-blk set bits directly in host_features?
> For example this is how virtio-net does it.
> This would remove the need for virtio_add_feature calls.
Maybe this should be the best approach!
What do you think if I send a trivial patch to add host_features
variable like for virtio-net and change the "config_wce" and "scsi" definition?
Then I will change also this patch to set directly the bits.
Thanks,
Stefano
