B2.68 ID_AA64PFR1_EL1, AArch64 Processor Feature Register 1, EL1

The ID_AA64PFR1_EL1 provides additional information about implemented core features in AArch64.

Bit field descriptions

ID_AA64PFR1_EL1 is a 64-bit register, and is part of the Identification registers functional group.

This register is Read Only.

Figure B2-51 ID_AA64PFR1_EL1 bit assignments
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RES0, [63:8]
SSBS, [7:4]

PSTATE.SSBS. The possible values are:

0x1AArch64 provides the PSTATE.SSBS mechanism to mark regions that are Speculative Store Bypassing Safe (SSBS), but does not implement the MSR/MRS instructions to directly read and write the PSTATE.SSBS field.
RES0, [3:0]

ID_AA64PFR1_EL1 is architecturally mapped to External register EDPFR.

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

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