Re: [PATCH RFC 1/3] Drivers: hv: kvp: convert userspace/kernel communication to using char device

2015-02-27 17:14+0100, Vitaly Kuznetsov:

Re-implement the communication using misc char device. Use ioctl to do
kernel/userspace version negotiation (doesn't make much sense at this moment
as we're breaking backwards compatibility but can be used in future).

The main question is whether we want to abolish backward compatibility;
kernel rules are usually against breakages and it's hard to prove that
the bundled daemon is a sole user and gets updated at the same time.
(Note: I'd gladly break anything.)

The ioctl is used too creatively for my liking: as an out-of-band
communication that is required after the main channel has been opened.
It would be simpler to inject the version into first x bytes of the
stream, making a read() after open() mandatory.

(I've only done a high level overview so far.)