RTEMS 4.6.0pre5 On-Line Library

Implicit Synchronization Using Task Priorities

RTEMS Remote Debugger Server Specifications

7.6.1: Implicit Synchronization Using Task Priorities

This chapter is relevant on Uniprocessor System (UP) only. However, it will also list the requirements for explicit synchronization on Multi-processor Systems (MP). Below are the task priorities sorted by high priority. They are not supposed to be equal :

Network Input Task. This is the highest priority task. This can be regarded as a software interrupt task for FreeBSD code,
RGDBSD command task. As this task waits on UDP sockets, it shall not prevent the previous task from running. As the main debug entry point, it should preempt any other task in the system,
RGDBSD event task. This task should preempt any task but the two mentionned before to signal a debug event to GDB. The command task shall be able to preempt this task for emergency command such as DEL, or REBOOT,
Applications tasks (task we are able to debug),

Using theses priorities eliminates the need for adding more synchronization objects in the next section. My belief is that symmetric MP support will require more important change in the RTEMS than RGDBSD itself like multiple scheduler queues, task to processor binding for non symmetric IO, use a different implementation for task_disable_preemption, ...

RTEMS Remote Debugger Server Specifications