Re: [Qemu-devel] [PATCH v2 2/5] virtio-blk: add "discard-wzeroes" boolean property

[Stefano Garzarella]

On Thu, Jan 31, 2019 at 03:40:38PM +0000, Dr. David Alan Gilbert wrote:
> * Stefano Garzarella (address@hidden) 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 <address@hidden>
> > Signed-off-by: Stefano Garzarella <address@hidden>
> > ---
> >  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