These are accesses from an external debug device. ARM recommends that these use an ARM Debug Interface v5, see the ARM Debug Interface v5 Architecture Specification, that provides a memory-mapped interface to the ETM registers.

An external debug device can also access a PTM through a Direct JTAG interface, or a similar interface.

These are accesses from a device in the system, such as a processor, that use the memory-mapped interface to the PTM registers, see Memory-mapped access.

If an implementation includes a memory-mapped processor interface to the PTM registers then it must also implement the software lock, controlled by the ETMLAR.

These are accesses that originate from an on-chip device, such as a processor, using the coprocessor interface to the PTM, see Coprocessor access.