[coyotos-dev] Some provisional resolutions

[Jonathan S. Shapiro]

Looks like we have a handle on how to repair the mess, but it's a fairly
major change. Here is a quick summary:

1. Processes are no longer notified on every run-in. This was always
dicey, and never hugely compelling. I decided to drop it for simplicity.
More on how to do media-style real time below.

2. The "short message" portion of a message is no longer delivered by
activation. An application must name an FCRB in the receive phase of the
IPC, and will receive the short message as the return value from the
receive phase.

3. The activation mechanism remains, but it no longer provides any sort
of generalized message interface. It is purely an in-process exception
handler. This, however, is good enough to implement user-level threading
and so forth.

4. We are considering [not sure yet] a "notify" bit in the FCRB. If the
notify bit is set, the FCRB is ready to be received (i.e. there is a
message ready), and the receiver is not currently receiving on that
FCRB, the receiver's activation handler will be invoked with enough
information to figure out what FCRB has pending input.

Almost everything else is unchanged.

For media real-time, where end of slice notification is required, we
will introduce a new exception type. If a process is not idle at end of
slice, and the end of slice notification is required, an exception will
be issued to the process.

A similar mechanism can be used for minor slice end to support
user-level thread scheduling.


shap
-- 
Jonathan S. Shapiro, Ph.D.
Managing Director
The EROS Group, LLC
+1 443 927 1719 x5100