You could also use a jack_rigbuffer_t, its lock free and hence should be RT thread safe.
You could write a known msg into the ring buffer from the RT thread, receive the msg from non real-time thread and do event passing from there.

-- 
Regards,
Karthik Poduval

On Wed, Sep 24, 2014 at 5:39 AM, Tim Goetze <tim@quitte.de> wrote:
[William Light]
>I'm avoiding blocking, of course, but I'm also worried about the
>potential scheduling implications of jumping into kernel-mode and back,
>and also the potential non-determinism of system call execution time.
>Are these things I should actually worry about?

I've been using pipes for message-passing the way Clemens mentioned in
realtime MIDI and audio threads for years without ever experiencing any
scheduling or blocking problems.

Cheers, Tim
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