LORSA_EL1, LORegion Start Address (EL1)

The LORSA_EL1 characteristics are:

Purpose

Indicates whether the current LORegion descriptor selected by LORC_EL1.DS is enabled, and holds the physical address of the start of the LORegion.

This register is part of the Virtual memory control registers functional group.

Configuration

This register is RES0 if any of the following apply:

RW fields in this register reset to architecturally UNKNOWN values.

This register is introduced in ARMv8.1.

Attributes

LORSA_EL1 is a 64-bit register.

Field descriptions

The LORSA_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
000000000000SA[51:48]SA[47:16]
SA[47:16]000000000000000Valid
313029282726252423222120191817161514131211109876543210

Any of the fields in this register are permitted to be cached in a TLB.

Bits [63:52]

Reserved, RES0.

SA[51:48], bits [51:48]
In ARMv8.2:

Extension to SA[47:16]. See SA[47:16] for more details.


In ARMv8.1:

Reserved, RES0.

SA[47:16], bits [47:16]

Bits [47:16] of the start physical address of the LORegion described in the current LORegion descriptor selected by LORC_EL1.DS. Bits[15:0] of this address are defined to be 0x0000.

When ARMv8.2-LPA is implemented, and 52-bit addresses and a 64KB translation granule are in use, SA[51:48] form the upper part of the address value. Otherwise, for implementations with fewer than 52 physical address bits, SA[51:48] are RES0.

Bits [15:1]

Reserved, RES0.

Valid, bit [0]

Indicates whether the current LORegion Descriptor is enabled.

ValidMeaning
0

Disabled

1

Enabled

Accessing the LORSA_EL1

This register can be read using MRS with the following syntax:

MRS <Xt>, <systemreg>

This register can be written using MSR (register) with the following syntax:

MSR <systemreg>, <Xt>

This syntax uses the following encoding in the System instruction encoding space:

<systemreg> op0op1CRnCRmop2
LORSA_EL11100010100100000

Accessibility

The register is accessible as follows:

Control Accessibility
E2HTGENSEL0EL1EL2EL3
xx0 - - n/a -
x01 - RWRWRW
x11 - n/a RWRW

This table applies to all instructions that can access this register.

Traps and enables

For a description of the prioritization of any generated exceptions, see section D1.13.2 (Synchronous exception prioritization) in the ARM® Architecture Reference Manual, ARMv8, for ARMv8-A architecture profile. Subject to the prioritization rules, the following traps and enables are applicable when accessing this register.

When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 && HCR_EL2.E2H==0 :

When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 && HCR_EL2.E2H==1 && HCR_EL2.TGE==0 :

When EL3 is implemented and is using AArch64 and SCR_EL3.NS==1 :




18/04/2017 17:00

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