Embedded Systems Design, 2nd Edition

232 Embedded systems design

such as invalidating caches to ensure that the new process

or task does not access incorrect information.

A thread has different characteristics:

• It has no additional context information beyond that stored

in the processor register set.

• Its ownership of resources is inherited from its parent task

or process.

With a simple operating system, there is no difference

between the thread context switch and the process level switch. As

a result, these terms almost become interchangeable. With a multi-

user, multitasking operating system, this is not the case. The

process or task is the higher level with the thread(s) the lower level. ...