In a computer system having a logical-partitioned server, each partition of the
server is provided with its own separate lock and access corridor, in addition
to a global lock. When the locking of a partition lock is followed by the locking
of the global lock, the system is serialized. The partition locks are controlled
by system firmware on behalf of an OS isolating each partition; however, the global
lock is controlled by the system firmware to be unlocked independent of the lock/unlock
status of the partition locks. In this manner, the ability or inability of an OS
that issued a machine check interrupt to unlock its partition lock after the machine
check analysis is complete is irrelevant; once the machine check analysis is complete,
the system firmware unlocks the global lock, giving other partitions access to
shared system resources to run their own machine checks.
