Interrupt Handling with MMU Hardware on an MMU-less OS

This post describes some work that I have just recently gotten to a point that it seems to be correct.  It was a long-running project that started around May 2010.

RTEMS Modular Task Scheduler

As I mentioned in my last post, this past summer I participated in the Google Summer of Code by working on the RTEMS project. I have hopefully ironed out the last few small details that prevented the basic infrastructure that I developed from being accepted into the RTEMS code base. In this post I describe the design of the new scheduler, and also comment on some of the problems that I faced when merging the work. At the end of the post is a list of remaining work for this project.

Pre-existing RTEMS Scheduler

New Modular Scheduler
  Scheduler Control Structure
  Ready Queue Encapsulation
  Per-Thread Metadata
  Scheduler Operations Table
  Configuring the Scheduler

Merging the New Scheduler
  Short-circuit Evaluation
  PowerPC overheads

Open Issues
Improper Encapsulation
Interrupt Service Routine (ISR) Latency
Documentation
Configuration
New Technologies