Hi!

> Instructions
> ------------
> senduipi <index> - send a user IPI to a target task based on the UITT index.
> 
> clui - Mask user interrupts by clearing UIF (User Interrupt Flag).
> 
> stui - Unmask user interrupts by setting UIF.
> 
> testui - Test current value of UIF.
> 
> uiret - return from a user interrupt handler.

Are other CPU vendors allowed to implement compatible instructions?

If not, we should probably have VDSO entries so kernel can abstract
differences between CPUs.

> Untrusted processes
> -------------------
> The current implementation expects only trusted and cooperating processes to
> communicate using user interrupts. Coordination is expected between processes
> for a connection teardown. In situations where coordination doesn't happen
> (say, due to abrupt process exit), the kernel would end up keeping shared
> resources (like UPID) allocated to avoid faults.

Keeping resources allocated after process exit is a no-no.

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek