MDRAR_EL1, Monitor Debug ROM Address Register
The MDRAR_EL1 characteristics are:
Purpose
Defines the base physical address of a 4KB-aligned memory-mapped debug component, usually a ROM table that locates and describes the memory-mapped debug components in the system. Armv8 deprecates any use of this register.
Configuration
AArch64 System register MDRAR_EL1 bits [63:0] are architecturally mapped to AArch32 System register DBGDRAR[63:0] .
Attributes
MDRAR_EL1 is a 64-bit register.
Field descriptions
The MDRAR_EL1 bit assignments are:
63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ROMADDR[51:48] | ROMADDR[47:12] | ||||||||||||||||||
ROMADDR[47:12] | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Valid | ||||||||||||||||||||
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Bits [63:52]
Reserved, RES0.
ROMADDR[51:48], bits [51:48]
When ARMv8.2-LPA is implemented:
When ARMv8.2-LPA is implemented:
Extension to ROMADDR[47:12]. See ROMADDR[47:12] for more details.
Otherwise:
Otherwise:
Reserved, RES0.
ROMADDR[47:12], bits [47:12]
Bits[47:12] of the ROM table physical address.
When ARMv8.2-LPA is implemented, ROMADDR[51:48] forms the upper part of the address value. Otherwise, ROMADDR[51:48] is RES0.
If the physical address size in bits (PAsize) is less than 52, then the register bits corresponding to ROMADDR [51:PAsize] are RES0.
Bits [11:0] of the ROM table physical address are zero.
Arm strongly recommends that bits ROMADDR[(PAsize-1):32] are zero in any system that supports AArch32 at the highest implemented Exception level.
In an implementation that includes EL3, ROMADDR is an address in Non-secure memory. It is IMPLEMENTATION DEFINED whether the ROM table is also accessible in Secure memory.
Bits [11:2]
Reserved, RES0.
Valid, bits [1:0]
This field indicates whether the ROM Table address is valid. The permitted values of this field are:
Valid | Meaning |
---|---|
0b00 |
ROM Table address is not valid. Software must ignore ROMADDR. |
0b11 |
ROM Table address is valid. |
Other values are reserved.
Accessing the MDRAR_EL1
Accesses to this register use the following encodings:
MRS <Xt>, MDRAR_EL1
op0 | CRn | op1 | op2 | CRm |
---|---|---|---|---|
0b10 | 0b0001 | 0b000 | 0b000 | 0b0000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDRA> != '00' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return MDRAR_EL1; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return MDRAR_EL1; elsif PSTATE.EL == EL3 then return MDRAR_EL1;