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PMCEID2, Performance Monitors Common Event Identification register 2

The PMCEID2 characteristics are:

Purpose

Defines which common architectural events and common microarchitectural events are implemented, or counted, using PMU events in the range 0x4000 to 0x401F.

When the value of a bit in the register is 1 the corresponding common event is implemented and counted.

Note

Arm recommends that, if a common event is never counted, the value of the corresponding register bit is 0.

For more information about the common events and the use of the PMCEIDn registers see The section describing 'Event numbers and common events' in chapter D5 'The Performance Monitors Extension' of the Arm Architecture Reference Manual, for Armv8-A architecture profile.

Configuration

External register PMCEID2 bits [31:0] are architecturally mapped to AArch64 System register PMCEID0_EL0[63:32] .

External register PMCEID2 bits [63:32] are architecturally mapped to AArch32 System register PMCEID2[31:0] .

PMCEID2 is in the Core power domain.

This register is present only from Armv8.1. Otherwise, direct accesses to PMCEID2 are RES0.

Attributes

PMCEID2 is a 32-bit register.

Field descriptions

The PMCEID2 bit assignments are:

313029282726252423222120191817161514131211109876543210
IDhi<n>, bit [n]

IDhi<n>, bit [n], for n = 0 to 31

From Armv8.1:

IDhi[n] corresponds to common event (0x4000 + n).

For each bit:

IDhi<n>Meaning
0b0

The common event is not implemented, or not counted.

0b1

The common event is implemented.

A bit that corresponds to a reserved event number is reserved. The value might be used in a future revision of the architecture to identify an additional common event.

Note

Such an event might be added retrospectively to an earlier version of the PMU architecture, provided the event does not require any additional PMU features and has an event number that can be represented in the PMCEID<n> registers of that earlier version of the PMU architecture.


Otherwise:

Reserved, RES0.

Accessing the PMCEID2

Note

AllowExternalPMUAccess() has a new definition from Armv8.4. Refer to the Pseudocode definitions for more information.

PMCEID2 can be accessed through the external debug interface:

ComponentOffsetInstance
PMU0xE28PMCEID2

This interface is accessible as follows:

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


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