Re: [PATCH] hw/vhost-user-i2c: Add support for VIRTIO_I2C_F_ZERO_LENGTH_REQUEST

[Viresh Kumar]

On 10-02-22, 08:29, Alex Bennée wrote:
> 
> Viresh Kumar <viresh.kumar@linaro.org> writes:
> > @@ -113,8 +117,10 @@ static void vu_i2c_set_status(VirtIODevice *vdev, 
> > uint8_t status)
> >  static uint64_t vu_i2c_get_features(VirtIODevice *vdev,
> >                                      uint64_t requested_features, Error 
> > **errp)
> >  {
> > -    /* No feature bits used yet */
> > -    return requested_features;
> > +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> > +
> > +    virtio_add_feature(&requested_features, 
> > VIRTIO_I2C_F_ZERO_LENGTH_REQUEST);
> > +    return vhost_get_features(&i2c->vhost_dev, feature_bits, 
> > requested_features);
> >  }
> 
> It's a bit weird we set it and then pass it to the vhost-user backend.
> It does raise the question of why the stub actually cares about feature
> bits at all when really it's a negotiation with the backend.
> 
> IOW what would happen if we just called:
> 
>     return vhost_get_features(&i2c->vhost_dev, feature_bits, -1);

That works as well.

Also I noticed just now that I haven't added VHOST_INVALID_FEATURE_BIT
at the end of the feature_bits[]. Will fix that.

-- 
viresh