[rtmk-discuss] regarding migrating threads

[Johan Rydberg]

Hello Mr. Archive,

To implement migrating threads the concept of static threads
(as implemented now) have to be changed.  We change the thread
abstraction and introduce a new componenet:

 * Executing unit, called activation.  Holds for example
   hardware registers, and also suspend counter.

 * Scheduling parameters, called thread.  Contains priority
   and scheduling policy.  
A thread is no longer bound to a specific task.  This gives
us the possibilty to migrate a thread into any context (task)
in the system.

For a thread to be able to execute any code, it has to be
attached ("populate") to an activation.  The thread maintains
a stack for attached activations, with the current activation
on top.

When a thread migrates into a new context, an activation
is pushed upon threads activation stack.  When it migrates
back, activation is poped. 
I will probably implement this sometime in the (near) future.

@end