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MDSELR_EL1: Breakpoint and Watchpoint Selection Register

Purpose

Selects the current breakpoints or watchpoints accessed by System register instructions.

Configuration

This register is present only when FEAT_Debugv8p9 is implemented. Otherwise, direct accesses to MDSELR_EL1 are UNDEFINED.

Attributes

MDSELR_EL1 is a 64-bit register.

Field descriptions

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
RES0
RES0BANKRES0

Bits [63:6]

Reserved, RES0.

BANK, bits [5:4]

Breakpoint and watchpoint bank select.

BANKMeaningApplies when
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

Each of the following register names accesses a register for breakpoint or watchpoint <n>, where n = UInt(MDSELR_EL1.BANK:m[3:0]):

This field is ignored by the PE and treated as zeros when any of the following are true:

The reset behavior of this field is:

Accessing this field has the following behavior:

Bits [3:0]

Reserved, RES0.

Accessing MDSELR_EL1

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.

Accesses to this register use the following encodings in the System register encoding space:

MRS <Xt>, MDSELR_EL1

op0op1CRnCRmop2
0b100b0000b00000b01000b010

if 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); elsif HaveEL(EL3) && MDCR_EL3.TDA == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = MDSELR_EL1; 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); elsif HaveEL(EL3) && MDCR_EL3.TDA == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = MDSELR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = MDSELR_EL1;

MSR MDSELR_EL1, <Xt>

op0op1CRnCRmop2
0b100b0000b00000b01000b010

if 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); elsif HaveEL(EL3) && MDCR_EL3.TDA == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else MDSELR_EL1 = X[t, 64]; 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); elsif HaveEL(EL3) && MDCR_EL3.TDA == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else MDSELR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then MDSELR_EL1 = X[t, 64];