Re: [libvirt] [PATCH v2 4/4] Documentation/vfio-mediated-device.txt: update for aggregation attribute

[Cornelia Huck <cohuck@redhat.com>]

On Fri, 27 Jul 2018 10:16:58 +0800
Zhenyu Wang <zhenyuw@linux.intel.com> wrote:

> On 2018.07.26 17:46:40 +0200, Cornelia Huck wrote:
> > On Fri, 20 Jul 2018 10:19:28 +0800
> > Zhenyu Wang <zhenyuw@linux.intel.com> wrote:
> >   
> > > Update mdev doc on new aggregration attribute and instances attribute
> > > for mdev.
> > > 
> > > Cc: Kirti Wankhede <kwankhede@nvidia.com>
> > > Cc: Alex Williamson <alex.williamson@redhat.com>
> > > Cc: Kevin Tian <kevin.tian@intel.com>
> > > Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
> > > ---
> > >  Documentation/vfio-mediated-device.txt | 39 ++++++++++++++++++++++----
> > >  1 file changed, 33 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/Documentation/vfio-mediated-device.txt b/Documentation/vfio-mediated-device.txt
> > > index c3f69bcaf96e..9ec9495dcbe7 100644
> > > --- a/Documentation/vfio-mediated-device.txt
> > > +++ b/Documentation/vfio-mediated-device.txt
> > > @@ -211,12 +211,20 @@ Directories and files under the sysfs for Each Physical Device
> > >    |     |   |--- description
> > >    |     |   |--- [devices]
> > >    |     |--- [<type-id>]
> > > -  |          |--- create
> > > -  |          |--- name
> > > -  |          |--- available_instances
> > > -  |          |--- device_api
> > > -  |          |--- description
> > > -  |          |--- [devices]
> > > +  |     |    |--- create
> > > +  |     |    |--- name
> > > +  |     |    |--- available_instances
> > > +  |     |    |--- device_api
> > > +  |     |    |--- description
> > > +  |     |    |--- [devices]
> > > +  |     |--- [<type-id>]
> > > +  |     |    |--- create
> > > +  |     |    |--- name
> > > +  |     |    |--- available_instances
> > > +  |     |    |--- device_api
> > > +  |     |    |--- description
> > > +  |     |    |--- <aggregation>
> > > +  |     |    |--- [devices]
> > >  
> > >  * [mdev_supported_types]
> > >  
> > > @@ -260,6 +268,19 @@ Directories and files under the sysfs for Each Physical Device
> > >    This attribute should show brief features/description of the type. This is
> > >    optional attribute.
> > >  
> > > +* <aggregation>
> > > +
> > > +  The description is to show feature for one instance of the type. <aggregation>  
> > 
> > You are talking about "one instance" here. Can this be different for
> > the same type with different physical devices?
> >  
> 
> I would expect for normal mdev types, driver might expose like x2, x4, x8 types
> which split hw resource equally. But for type with aggregation feature, it can
> set user wanted number of instances. Sorry maybe my use of word was not clear, how
> about "one example of type"?


Maybe my question was confusing as well...

<aggregation> is an attribute that is exposed for a particular type
under a particular physical device.

- If <aggregation> is always the same for that particular type,
  regardless of which physical device we're dealing with, let's just
  drop the "one instance" sentence.
- If it instead depends on what physical device we're handling, I'd
  write something like "The contents of this attribute depend both on
  the type and on the particular instance."