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

[Cornelia Huck <cohuck@redhat.com>]

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?

> +  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?

> +
> +Example::
> +
> +	# echo "<uuid>,instances=N" > create
> +
>  Directories and Files Under the sysfs for Each mdev Device
>  ----------------------------------------------------------
>  
> @@ -268,6 +289,7 @@ Directories and Files Under the sysfs for Each mdev Device
>    |- [parent phy device]
>    |--- [$MDEV_UUID]
>           |--- remove
> +	 |--- instances
>           |--- mdev_type {link to its type}
>           |--- vendor-specific-attributes [optional]
>  
> @@ -281,6 +303,11 @@ Example::
>  
>  	# echo 1 > /sys/bus/mdev/devices/$mdev_UUID/remove
>  
> +* instances
> +
> +For aggregation type show number of instances assigned for this mdev. For normal
> +type or default will just show one instance.
> +
>  Mediated device Hot plug
>  ------------------------
>