ARM count

12.2.8. Cycle Count Register

The PMCCNTR characteristics are:

Purpose

Counts processor clock cycles.

Usage constraints

The PMCCNTR is:

• accessible as determined by the User Enable Register
• common to Secure and Non-secure states.

Configurations

Available in all configurations.

Attributes

See the register summary in Table 4.17.

To access the PMCCNTR, use:

MRC p15, 0, , c9, c13, 0 ; Read PMCCNTR

MCR p15, 0, , c9, c13, 0 ; Write PMCCNTR

The PMCCNTR must be disabled before software can write to it. Any attempt by software to write to this register when enabled is Unpredictable.