Re: [PATCH v3 02/21] include/hw: document vhost_dev feature life-cycle

[Alex Bennée]

Jason Wang <jasowang@redhat.com> writes:

> 在 2022/7/27 03:21, Alex Bennée 写道:
>> Try and explicitly document the various state of feature bits as
>> related to the vhost_dev structure. Importantly the backend_features
>> can advertise things like VHOST_USER_F_PROTOCOL_FEATURES which is
>> never exposed to the driver and is only present in the vhost-user
>> feature negotiation.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>
>
> Acked-by: Jason Wang <jasowang@redhat.com>
>
> Maybe it's better to document backend_cap as well which is only used
> for vhost-kernel/vdpa.
>
> And in the future we should try to unify them.

I'm fairly sure there is a lot of duplication across the various
vhost_dev, VirtIO, and individual virtio structures. Documenting is a
first step to cleaning that up but ideally we need more coverage to make
sure we aren't inadvertently breaking things when we refactor.

>
> Thanks
>
>
>> ---
>>   include/hw/virtio/vhost.h | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
>> index a346f23d13..586c5457e2 100644
>> --- a/include/hw/virtio/vhost.h
>> +++ b/include/hw/virtio/vhost.h
>> @@ -86,8 +86,11 @@ struct vhost_dev {
>>       /* if non-zero, minimum required value for max_queues */
>>       int num_queues;
>>       uint64_t features;
>> +    /** @acked_features: final set of negotiated features */
>>       uint64_t acked_features;
>> +    /** @backend_features: backend specific feature bits */
>>       uint64_t backend_features;
>> +    /** @protocol_features: final negotiated protocol features */
>>       uint64_t protocol_features;
>>       uint64_t max_queues;
>>       uint64_t backend_cap;


-- 
Alex Bennée