[Xen-devel] USB Xen Summit status summary

[Nivedita Singhvi <nsnix@xxxxxxxxxxx>]

Since Harry Butterworth, who's been working on the USB
virtualization couldn't attend the Xen Summit, I sat in
for him and am providing this summary:

Here were the options under consideration:

1. Xen includes current patch Harry had put out, which
   includes his IDC API.
2. Harry puts out a simpler USB driver without his IDC
   API, written directly to the current Xen bus/store API,
   and reducing to only features deemed needed for Xen,
   see if that will be accepted into tree.
3. Examine USBoverIP patches (currently in -mm tree)
   and see if those provide all the functionality we
   need.
4. Throw away everything and have someone else rewrite
   from scratch.

There was a brief discussion at the Client (Graphics,
USB...) session on USB. Ewan and several community folks
were present. Opinions expressed:

- Harry's IDC code and current code will not make it
  into tree as is [consensus]
- IDC piece very unlikely to be accepted into Linux mainline,
  hence should not go into Xen tree
- API code is orthogonal to USB driver piece, should be
  a seperate patch/discussion [consensus]
- Best option is (2), rewrite code to leaner, simpler
  USB driver with minimal functionality, and get that into
  tree
- Noone in session had looked at USBoverIp patches
- There were some good ideas in the IDC API that needed
  to be discussed/incorporated in Xen

Other input/questions received:
- Need to get USB community input
- What were the issues that were left? Are they resolved?
  If so, what's the current working state of the patch?
- Keir: rewrite to a simpler driver without the IDC API
  as the xenbus/store stuff is pretty baked into Xen now,
  might want to do some cleanups in this area.
- Ian: look at USBoverIP, tried it and it seems to
  work, but not sure if that's the right solution

Current Issues/Design questions:
- Harry's code supports back/front module load/unload
  (useful during development, if nothing else).
- Harry's code is not written to Ewan's last common
  code pullout API
- What other code functionality can be dropped in order
  to make it smaller?

[All misrepresentations and errors are mine, I'm operating
 from memory and on occasion what I heard over the crowd noise :)]

Hope that initiates the necessary conversation on this...

thanks,
Nivedita


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