A method and apparatus is disclosed for improving the MSI and MSI-X
specifications by implementing an efficient delivery and clearing
mechanism for interrupt conditions to increase performance between the
driver and hardware/firmware interface while ensuring that no interrupts
are lost in the process. In particular, an auto clear function is
employed to eliminate the need for drivers in the host to send writes
over the PCI-based bus to deassert and assert attention enable register
bits and clear down attention register bits, and a fail safe mechanism is
utilized to prevent lost interrupts.