Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 693

PAL_PREFETCH_VISIBILITY
This procedure, when used to delete a memory range on-line, will ensure that all of the
conditions described in both of the preceding paragraphs regarding transition of virtual
memory attributes and physical memory attributes are met.
If the processor implementation does not require this procedure call to be made on
remote processors in the sequences, this procedure will return a 1 upon successful
completion.
A return value of 0 upon successful completion of this procedure is an indication to
software that the processor implementation requires that this call be performed on all
processors in the coherence domain to make prefetches visible in the sequences.
These return code can be used to tune the architected sequence to the particular
system on which is running; see Section 4.4.11, "Memory Attribute Transition" for
details.
Volume 2, Part 1: Processor Abstraction Layer 2:445