B1.68 ID_MMFR0, Memory Model Feature Register 0

The ID_MMFR0 provides information about the memory model and memory management support in AArch32.

Bit field descriptions

ID_MMFR0 is a 32-bit register, and is part of the Identification registers functional group.

This register is Read Only.

Figure B1-53 ID_MMFR0 bit assignments
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InnerShr, [31:28]

Indicates the innermost shareability domain implemented:

0x1Implemented with hardware coherency support.
FCSE, [27:24]

Indicates support for Fast Context Switch Extension (FCSE):

0x0Not supported.
AuxReg, [23:20]

Indicates support for Auxiliary registers:

0x2Support for Auxiliary Fault Status Registers (AIFSR and ADFSR) and Auxiliary Control Register.
TCM, [19:16]

Indicates support for TCMs and associated DMAs:

0x0Not supported.
ShareLvl, [15:12]

Indicates the number of shareability levels implemented:

0x1Two levels of shareability implemented.
OuterShr, [11:8]

Indicates the outermost shareability domain implemented:

0x1Implemented with hardware coherency support.
PMSA, [7:4]

Indicates support for a Protected Memory System Architecture (PMSA):

0x0Not supported.
VMSA, [3:0]

Indicates support for a Virtual Memory System Architecture (VMSA).


Support for:

  • VMSAv7, with support for remapping and the Access flag.
  • The PXN bit in the Short-descriptor translation table format descriptors.
  • The Long-descriptor translation table format.

ID_MMFR0 is architecturally mapped to AArch64 register ID_MMFR0_EL1. See B2.74 ID_MMFR0_EL1, AArch32 Memory Model Feature Register 0, EL1.

There is one copy of this register that is used in both Secure and Non-secure states.

Must be interpreted with ID_MMFR1, ID_MMFR2, ID_MMFR3, and ID_MMFR4. See:

Bit fields and details not provided in this description are architecturally defined. See the Arm® Architecture Reference Manual Armv8, for Armv8-A architecture profile.

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