On Oct 30 2017 15:33, Oleksandr Andrushchenko wrote:
This is an attempt to summarize previous discussions on Xen para-virtual sound driver.
A first attempt has been made to upstream the driver [1] which brought number of fundamental questions, one of the biggest ones was that the frontend driver has no means to synchronize its period elapsed event with the host driver, but uses software emulation on the guest side [2] with a timer. In order to address this a change to the existing Xen para-virtual sound protocol [3] was proposed to fill this gap [4] and remove emulation:
- Introduced a new event channel from back to front
- New event with number of bytes played/captured (XENSND_EVT_CUR_POS,
to be used for sending snd_pcm_period_elapsed at frontend (in Linux implementation, sent in bytes, not frames to make the protocol generic and consistent) 3. New request for playback/capture control (XENSND_OP_TRIGGER) with start/pause/stop/resume sub-ops.
Along with these changes other comments on the driver were addressed, e.g. split into smaller chunks, moved the driver from misc to xen etc. [5].
Hope, this helps to get the full picture of what was discussed and makes it possible to move forward: if the approach seems ok, then I'll start upstreaming the changes to the sndif protocol and then will send the updated version of the driver for the further review.
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Generally, receiving no reactions means that readers/reviewers don't get enough information for your idea yet. (Of course, there's a probability that your work attracts no one...) In this case, submitting more resources is better, rather than requesting comments to them. For instance, you can point links to backend/frontend implementation as para-virtualization drivers which use the new feature of interface, if you did work for it. Indicating procedure to use a series of your work is better for test, if possible.
[1] https://www.ietf.org/rfc/rfc0822.txt
Regards
Takashi Sakamoto