One embodiment of the present invention provides a system that supports
inter-process communication through use of a conditional trap instruction.
The system operates by allowing a first process to send a communication to
a second process by writing to a register that is visible to the second
process. The second process then examines a value in the register by
executing the conditional trap instruction. If the value in the register
satisfies a condition specified by the conditional trap instruction, the
system executes a trap handling routine that takes an action in response
to the communication from the first process. If the value in the register
does not satisfy the condition, the system takes no action and proceeds
with execution of the code. In one embodiment of the present invention,
the first process writes to the register by causing an interrupt that
writes to the register.
