Clans & Chiefs

Clans & Chiefs are a security mechanism for:

task control: define ownership of tasks
- a task creating another task becomes the chief of that task
- the set of tasks created by a chief is that chief's clan
- task can be killed only
  1. directly by its chief
  2. indirectly when its chief is killed
communication control: restrict the flow of messages
- intra-clan messages are delivered directly
- inter-clan messages are redirected to chief
- chief can forward the message transparently

Depth of hierarchy is limited (16 on MIPS).

Note: Clans & chiefs will be replaced by a better model!

Inter-Clan IPC

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Gernot Heiser 2002-08-07