Tasks in Enclaves

Using tasks in enclaves offers all the advantages of enclaves and allows the enclave to perform functions that require a task environment, such as supervisor calls. Unlike SRBs, tasks can dynamically leave and join an enclave as they finish one piece of work and begin another.

A subsystem can create an enclave using the IWM4ECRE macro, join the task to the enclave using the IWMEJOIN macro, process the work request, and remove the task from the enclave using the IWMELEAV macro. If a task joins an enclave and subsequently attaches subtasks, the subtasks are automatically joined to the enclave. The interactions between enclaves and attach/detach are summarized as follows:

• Subtasks attached while the mother task belongs to an enclave inherit membership in the same enclave.
• Subtasks that already exist when the mother task joins an enclave are not automatically made part of the enclave although they may explicitly join and leave the enclave using IWMEJOIN and IWMELEAV.
• Tasks which inherit membership in an enclave can only leave the enclave by terminating or by deleting the entire enclave.
• Mother tasks with subtasks that inherited enclave membership cannot leave the enclave until all such subtasks terminate.