SPMROOTCR_EL3 System Performance Monitors Root and Realm Control Register when FEAT_RME is implemented, FEAT_SPMU is implemented, and FEAT_AA64 is implemented Controls observability of Root and Realm events by System PMU <s>. Unknown SPMROOTCR_EL3 is a 64-bit register. IMPLEMENTATION DEFINED 63 32 63:32 IMPLEMENTATION DEFINED observation controls. Additional IMPLEMENTATION DEFINED bits to control certain types of filter or events by System PMU <s>. ID 31 31 31 Reserved, RAO. Indicates SPMROOTCR_EL3 is implemented by System PMU <s>. 30 4 30:4 Reserved, RES0. NAO 3 3 0 Non-attributable Observation. Controls whether events or monitorable characteristics not attributable with any source can be monitored by System PMU <s>. When both SPMROOTCR_EL3 and SPMSCR_EL1 are implemented, non-attributable events are counted only if both SPMROOTCR_EL3.NAO is 1 and SPMSCR_EL1.{NAO, SO} is nonzero. SPMROOTCR_EL3.NAO has the opposite reset polarity to SPMSCR_EL1.NAO. 0b0 Events not attributable with any event source are not counted by System PMU <s>. 0b1 Counting non-attributable events by System PMU <s> is not prevented by this mechanism. '1' When System PMU <s> can count or monitor non-attributable events 3 3 3 Reserved, RES0. Otherwise 2 2 2 Reserved, RES0. RLO 1 1 1 Realm Observation. Controls whether events or monitorable characteristics attributable to a Realm event source can be monitored by System PMU <s>. 0b0 Events attributable to a Realm event source are not counted by System PMU <s>. 0b1 Counting events by System PMU <s> that are attributable to a Realm event source is not prevented by this mechanism. '0' RTO 0 0 0 Root Observation. Controls whether events or monitorable characteristics attributable to a Root event source can be monitored by System PMU <s>. 0b0 Events attributable to a Root event source are not counted by System PMU <s>. 0b1 Counting events by System PMU <s> that are attributable to a Root event source is not prevented by this mechanism. '0' To access SPMROOTCR_EL3 for System PMU <s>, set SPMSELR_EL0.SYSPMUSEL to s. SPMROOTCR_EL3 reads-as-zero and ignores writes if any of the following are true: System PMU <s> is not implemented. System PMU <s> does not implement SPMROOTCR_EL3. MRS <Xt>, SPMROOTCR_EL3 if !(IsFeatureImplemented(FEAT_RME) && IsFeatureImplemented(FEAT_SPMU) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then Undefined(); elsif PSTATE.EL == EL2 then Undefined(); elsif PSTATE.EL == EL3 then X{64}(t) = SPMROOTCR_EL3(UInt(SPMSELR_EL0().SYSPMUSEL)); end; MSR SPMROOTCR_EL3, <Xt> if !(IsFeatureImplemented(FEAT_RME) && IsFeatureImplemented(FEAT_SPMU) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then Undefined(); elsif PSTATE.EL == EL2 then Undefined(); elsif PSTATE.EL == EL3 then if IsFeatureImplemented(FEAT_FGWTE3) && FGWTE3_EL3().SPMROOTCR_EL3 == '1' then AArch64_SystemAccessTrap(EL3, 0x18); else SPMROOTCR_EL3(UInt(SPMSELR_EL0().SYSPMUSEL)) = X{64}(t); end; end; 2026-03-26 20:27:25 2026-03_rel