[libvirt] [RFC PATCH 00/11] Add mdev reporting capability to the nodedev driver

[Daniel P. Berrange]

On Wed, Mar 29, 2017 at 02:51:10PM +0200, Erik Skultety wrote:
> This series enables the node device driver to report information about the
> existing mediated devices on the host. There is no device creation involved
> yet. The information reported by the node device driver is split into two
> parts, one that is reported within the physical parent's capabilities
> (the generic stuff that comes from the mdev types' sysfs attributes, note the
>  'description' attribute which is verbatim - raw,unstructured string) and the
> other that is reported within the mdev child device and merely contains the
> mdev type id, which the device was instantiated from, and the iommu group
> number.
> 
> Basically, the format of the XML I went for is as follows:
> 
> PCI parent:
> <device>
>   <name>pci_0000_06_00_0</name>
>   <path>/sys/devices/.../0000:06:00.0</path>
>   <parent>pci_0000_05_08_0</parent>
>   ...
>   <capability type='pci'>
>     ...
>     <capability type='mdev'>
>       <type id='nvidia-11'>
>         <name>GRID M60-0B</name>
>         <description>num_heads=2, frl_config=45, framebuffer=512M, max_resolution=2560x1600, max_instance=16</description>

This 'description' field is pretty horrific.

We were quite clear that we were not going to expose arbitrary attributes
in the XML without modelling them explicitly as XML elements. Using the
description field in this way is just doing arbitrary attribute passthrough
via the backdoor - it is clear that applications are doing to end up parsing
this 'description' data and will them complain if we later change it.

So, NACK to including a description element with this kind of content.

Regards,
Daniel
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