Re: [PATCH] vhost-user: Fix protocol feature bit conflict

[Viresh Kumar]

On 16-10-23, 12:40, Alex Bennée wrote:
> 
> Viresh Kumar <viresh.kumar@linaro.org> writes:
> 
> > On 16-10-23, 11:45, Manos Pitsidianakis wrote:
> >> On Mon, 16 Oct 2023 11:32, Hanna Czenczek <hreitz@redhat.com> wrote:
> >> > diff --git a/include/hw/virtio/vhost-user.h
> >> > b/include/hw/virtio/vhost-user.h
> >> > index 9f9ddf878d..1d4121431b 100644
> >> > --- a/include/hw/virtio/vhost-user.h
> >> > +++ b/include/hw/virtio/vhost-user.h
> >> > @@ -29,7 +29,8 @@ enum VhostUserProtocolFeature {
> >> >     VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
> >> >     VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
> >> >     VHOST_USER_PROTOCOL_F_STATUS = 16,
> >> > -    VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 17,
> >> > +    /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */
> >> > +    VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 18,
> >> >     VHOST_USER_PROTOCOL_F_MAX
> >> > };
> >> 
> >> May I ask, why not define VHOST_USER_PROTOCOL_F_XEN_MMAP as well instead of
> >> a comment mention?
> >
> > Perhaps because we will never use it from Qemu code ?
> 
> Vikram's work on enabling xenpvh support will mean enabling grant
> support and while I suspect most VirtIO backends will be within QEMU
> itself if it ever want to off-load something to a vhost-user backend it
> will need to ensure this flag is set.

Hanna,

It would be good to define it then in the current commit itself.

-- 
viresh