Task Creation and Deletion: task_new System Call

System has fixed number of tasks, initially all inactive.
Inactive task is essentially a capability to create an active one.
Task is active iff it has a valid pager.
task_new deletes an (active or inactive) task and creates a new one
(with task same number but different version, hence different ID).
New task can be
- active: syscall parameters specify start address, stack pointer,
  pager, exception handler, scheduling priority;
  - initially runs single thread (lthread 0);
- inactive: does not consume any resources,
  can optionally be donated to new chief.

Gernot Heiser 2002-08-07