B2.59
ID_AA64MMFR1_EL1, AArch64 Memory Model Feature Register 1, EL1
The ID_AA64MMFR1_EL1 provides information about the implemented memory model and memory
management support in the AArch64 Execution state.
Bit field descriptions
ID_AA64MMFR1_EL1 is a 64-bit register, and is part of the Identification registers functional group.
This register is Read Only.
SpecSEI
63
0
4 3
8 7
12 11
16 15
VH
VMID
20 19
HD
PAN
HAFDBS
24 23
28 27
XNX
32 31
LO
RES
0
Figure B2-43 ID_AA64MMFR1_EL1 bit assignments
RES0, [63:32]
RES0
Reserved.
XNX, [31:28]
Indicates whether provision of EL0 vs EL1 execute never control at Stage 2 is supported.
0x1
EL0/EL1 execute control distinction at Stage 2 bit is supported. All other values are
reserved.
SpecSEI, [27:24]
Describes whether the PE can generate SError interrupt exceptions from speculative reads of
memory, including speculative instruction fetches.
0x0
The PE never generates an SError interrupt due to an external abort on a speculative
read.
PAN, [23:20]
Privileged Access Never. Indicates support for the PAN bit in PSTATE, SPSR_EL1, SPSR_EL2,
SPSR_EL3, and DSPSR_EL0.
0x2
PAN supported and AT S1E1RP and AT S1E1WP instructions supported.
LO, [19:16]
Indicates support for LORegions.
0x1
LORegions are supported.
HD, [15:12]
Presence of Hierarchical Disables. Enables an operating system or hypervisor to hand over up to
4 bits of the last level page table descriptor (bits[62:59] of the page table entry) for use by
hardware for
IMPLEMENTATION DEFINED
usage. The value is:
0x2
Hierarchical Permission Disables and Hardware allocation of bits[62:59] supported.
VH, [11:8]
Indicates whether Virtualization Host Extensions are supported.
B2 AArch64 system registers
B2.59 ID_AA64MMFR1_EL1, AArch64 Memory Model Feature Register 1, EL1
100798_0300_00_en
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B2-224
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Summary of Contents for Cortex-A76 Core
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