The L bit indicates that the PMP entry is locked, that is, writes to the Configuration register (pmpicfg) and associated address registers (pmpaddr) are ignored. Locked PMP entries can only be unlocked with a system reset. In addition to locking the PMP entry, the L bit indicates whether the R/W/X permissions are enforced on Machine (M) mode accesses. When the L bit is set, these permissions are enforced for all privilege modes. When the L bit is clear, any M-mode access matching the PMP entry succeeds; the R/W/X permissions apply only to Supervisor (S) and User (U) modes.