MDSELR_EL1 Breakpoint and Watchpoint Selection Register when FEAT_Debugv8p9 is implemented and FEAT_AA64 is implemented Selects the current breakpoints or watchpoints accessed by System register instructions. Unknown MDSELR_EL1 is a 64-bit register. 63 6 63:6 Reserved, RES0. BANK 5 4 5:4 Breakpoint and watchpoint bank select. Each of the following register names accesses a register for breakpoint or watchpoint <n>, where n = UInt(MDSELR_EL1.BANK:m[3:0]): DBGBCR<m>_EL1. DBGBVR<m>_EL1. DBGWCR<m>_EL1. DBGWVR<m>_EL1. This field is ignored by the PE and treated as zeros when any of the following are true: Executing at EL3 and MDCR_EL3.EBWE is 0. Executing at EL2 and the Effective value of MDCR_EL2.EBWE is 0. Executing at EL1 and the Effective value of MDSCR_EL1.EMBWE is 0. 0b00 Select 0 to 15. 0b01 Select 16 to 31. When NUM_BREAKPOINTS > 16 or NUM_WATCHPOINTS > 16 0b10 Select 32 to 47. When NUM_BREAKPOINTS > 32 or NUM_WATCHPOINTS > 32 0b11 Select 48 to 63. When NUM_BREAKPOINTS > 48 or NUM_WATCHPOINTS > 48 AU NUM_BREAKPOINTS <= 16 NUM_WATCHPOINTS <= 16 RES0 RW 3 0 3:0 Reserved, RES0. When 16 or fewer breakpoints are implemented, 16 or fewer watchpoints are implemented, and MDSELR_EL1 is implemented as RAZ/WI, it is IMPLEMENTATION DEFINED whether these trap controls have any effect on accesses to MDSELR_EL1. MRS <Xt>, MDSELR_EL1 if !(IsFeatureImplemented(FEAT_Debugv8p9) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().EBWE == '0' then Undefined(); elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().TDA == '1' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HDFGRTR2_EL2().nMDSELR_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && MDCR_EL2().[TDE,TDA] != '00' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3().EBWE == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif HaveEL(EL3) && MDCR_EL3().TDA == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = MDSELR_EL1(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().EBWE == '0' then Undefined(); elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().TDA == '1' then Undefined(); elsif HaveEL(EL3) && MDCR_EL3().EBWE == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif HaveEL(EL3) && MDCR_EL3().TDA == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = MDSELR_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = MDSELR_EL1(); end; MSR MDSELR_EL1, <Xt> if !(IsFeatureImplemented(FEAT_Debugv8p9) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().EBWE == '0' then Undefined(); elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().TDA == '1' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HDFGWTR2_EL2().nMDSELR_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && MDCR_EL2().[TDE,TDA] != '00' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3().EBWE == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif HaveEL(EL3) && MDCR_EL3().TDA == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else MDSELR_EL1() = X{64}(t); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().EBWE == '0' then Undefined(); elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().TDA == '1' then Undefined(); elsif HaveEL(EL3) && MDCR_EL3().EBWE == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif HaveEL(EL3) && MDCR_EL3().TDA == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else MDSELR_EL1() = X{64}(t); end; elsif PSTATE.EL == EL3 then MDSELR_EL1() = X{64}(t); end; 2026-03-26 20:27:25 2026-03_rel