3.9.1. Access types

The ETM access permission descriptions refer to the following types of access:

Debugger accesses

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 an ETM through a Direct JTAG interface, or a similar interface.

Processor accesses through a memory-mapped interface

These are accesses from a device in the system, such as a processor, that use the memory-mapped interface to the ETM registers, see Memory-mapped access, ETMv3.2 and later.

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

Processor accesses through the coprocessor interface

These are accesses that originate from an on-chip device, such as a processor, using the coprocessor interface to the ETM, see Coprocessor access, ETMv3.1 and later.

An ETM can distinguish between memory-mapped debugger accesses and memory-mapped processor accesses.

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