ID_AA64ZFR0_EL1, SVE Feature ID register 0

The ID_AA64ZFR0_EL1 characteristics are:

Purpose

Provides additional information about the implemented features of the AArch64 Scalable Vector Extension, when the ID_AA64PFR0_EL1.SVE field is not zero.

For general information about the interpretation of the ID registers see Principles of the ID scheme for fields in ID registers

Configuration

This register is present only when SVE is implemented. Otherwise, direct accesses to ID_AA64ZFR0_EL1 are RAZ.

Attributes

ID_AA64ZFR0_EL1 is a 64-bit register.

Field descriptions

The ID_AA64ZFR0_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
00000000000000000000000000000000
0000000000000000000000000000SVEver
313029282726252423222120191817161514131211109876543210

Bits [63:4]

Reserved, RES0.

SVEver, bits [3:0]

Scalable Vector Extension instruction set version. The defined values of this field are:

SVEverMeaning
0b0000

SVE instructions are implemented.

All other values are reserved. This field is only valid if the ID_AA64PFR0_EL1.SVE field is not zero.

Accessing the ID_AA64ZFR0_EL1

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

MRS <Xt>, <systemreg>

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

<systemreg> op0CRnop1op2CRm
ID_AA64ZFR0_EL11100000001000100

Accessibility

The register is accessible as follows:

ConfigurationAccessibility
EL0EL1EL2EL3
SCR_EL3.NS == 0 && SCR_EL3.EEL2 == 0-ROn/aRO
HCR_EL2.TGE == 0 && (SCR_EL3.NS == 1 || SCR_EL3.EEL2 == 1)-RORORO
HCR_EL2.TGE == 1 && (SCR_EL3.NS == 1 || SCR_EL3.EEL2 == 1)-n/aRORO

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.




15/10/2018 19:26; 79a37e9f651257790ccdbbdd2c8c3713837d12fb

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