WRS.NTO
Wait on Reservation Set (Normal Time-Out)
WRS.NTO
Stalls the hart until a reservation set is invalid or a short timeout expires. Used for efficient polling/spinlocks.
Details
WRS.NTO (Wait on Reservation Set, No Timeout) causes the hart to pause until the reservation set established by an LR instruction is invalidated or an interrupt or trap is pending. Unlike WFI, it is expected to resume on any reservation invalidation.
Pseudocode Operation
while (reservation_valid() && !timeout) { pause(); }Example
WRS.NTO
Encoding
Binary Layout
000000001101
31:20
00000
19:15
000
14:12
00000
11:7
1110011
6:0