1. A method comprising: a first processor that implements an x86 architecture operating in an advanced synchronization mode, which includes specifying and acquiring exclusive access to a given memory resource, wherein specifying comprises executing a code sequence including: a plurality of locked memory mov instructions, each having an x86 LOCK instruction prefix and an address associated with the given memory resource, and an acquire instruction that is subsequent to the plurality of locked memory mov instructions; a second processor that implements the x86 architecture requesting access to the given memory resource and issuing a probe message; and in response to receiving the probe message and acquiring exclusive access to the given memory resource, the first processor responding to the probe message with a failure message denying the second processor access to the given memory resource.