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

On 2018.07.26 17:46:40 +0200, Cornelia Huck wrote: > On Fri, 20 Jul 2018 10:19:28 +0800 > Zhenyu Wang <zhenyuw(a)linux.intel.com&gt; wrote: > > > Update mdev doc on new aggregration attribute and instances attribute > > for mdev. > > > > Cc: Kirti Wankhede <kwankhede(a)nvidia.com&gt; > > Cc: Alex Williamson <alex.williamson(a)redhat.com&gt; > > Cc: Kevin Tian <kevin.tian(a)intel.com&gt; > > Signed-off-by: Zhenyu Wang <zhenyuw(a)linux.intel.com&gt; > > --- > > 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"? > > + is an optional attributes to show that [<type-id>]'s instances can be > > + aggregated to be assigned for one mdev device. Set number of instances by > > + appending "instances=N" parameter for create. Instances number can't exceed > > + available_instances number. Without "instances=N" parameter will be default > > + one instance to create. > > Could there be a case where available_instances is n, but aggregation > is only supported for a value m < n? If yes, should m be discoverable > via the "aggregation" attribute? > I don't think there could be a case for that. As for aggregation type, it represents minimal resource allocated for a singleton, I can't see any reason for possible m < n.