An apparatus and method provide a protocol for communicating between an
operating system that owns a shared resource and other operating systems
that use the shared resource so that the operating systems that use the
shared resource will not crash if the operating system that owns the
shared resource is restarted. Messages are defined that allow handshaking
between operating systems so that operating systems that share a resource
will realize the resource will be unavailable for some period of time,
and that allow resuming the sharing of the resource once the operating
system that owns the shared resource is restarted.