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PMCID1SR, CONTEXTIDR_EL1 Sample Register

The PMCID1SR characteristics are:

Purpose

Contains the sampled value of CONTEXTIDR_EL1, captured on reading PMPCSR[31:0].

Configuration

PMCID1SR is in the Core power domain.

Fields in this register reset to architecturally UNKNOWN values. These apply only on a Cold reset. The register is not affected by a Warm reset and is not affected by an External debug reset.

This register is present only from Armv8.2. Otherwise, direct accesses to PMCID1SR are RES0.

Implemented only when ARMv8.2-PCSample is implemented.

Note

Before Armv8.2, the PC Sample-based Profiling Extension can be implemented in the external debug register space, as indicated by the value of EDDEVID.PCSample.

Attributes

PMCID1SR is a 32-bit register.

Field descriptions

The PMCID1SR bit assignments are:

313029282726252423222120191817161514131211109876543210
CONTEXTIDR_EL1

CONTEXTIDR_EL1, bits [31:0]

From Armv8.2:

Context ID. The value of CONTEXTIDR that is associated with the most recent PMPCSR sample.

  • If EL1 is using AArch64, then the Context ID is sampled from CONTEXTIDR_EL1.
  • If EL1 is using AArch32, then the Context ID is sampled from CONTEXTIDR.
  • If EL3 is implemented and is using AArch32, then CONTEXTIDR is a banked register and PMCID1SR samples the current banked copy of CONTEXTIDR for the Security state that is associated with the most recent PMPCSR sample.

Because the value written to PMCID1SR is an indirect read of CONTEXTIDR, therefore it is CONSTRAINED UNPREDICTABLE whether PMCID1SR is set to the original or new value if a read of PMPCSR samples:

  • An instruction that writes to CONTEXTIDR_EL1.
  • The next Context synchronization event.
  • Any instruction executed between these two instructions.

On a Cold reset, this field resets to an architecturally UNKNOWN value.


Otherwise:

Reserved, RES0.

Accessing the PMCID1SR

IMPLEMENTATION DEFINED extensions to external debug might make the value of this register UNKNOWN, see 'Permitted behavior that might make the PC Sample-based profiling registers UNKNOWN' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile

PMCID1SR can be accessed through the external debug interface:

ComponentOffsetInstance
PMU0x208PMCID1SR

This interface is accessible as follows:

  • When IsCorePowered(), !DoubleLockStatus() and !OSLockStatus() access to this register is RO.
  • Otherwise access to this register returns an Error.
ComponentOffsetInstance
PMU0x228PMCID1SR

This interface is accessible as follows:

  • When IsCorePowered(), !DoubleLockStatus() and !OSLockStatus() access to this register is RO.
  • Otherwise access to this register returns an Error.


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