4.3.28. c13, Context ID Register

The CONTEXTIDR characteristics are:

Purpose
  • Holds a process IDentification (ID) value for the running process.

  • The Embedded Trace Macrocell (ETM) and the debug logic use this register. The ETM can broadcast its value to indicate the process that is running. You must program each process with a unique number.

  • Enables process dependent breakpoints and instructions.

Usage constraints

The CONTEXTIDR is:

  • a read/write register

  • accessible in Privileged mode only.

Configurations

Available in all processor configurations.

Attributes

The CONTEXTIDR, bits [31:0] contain the process ID number.

To use the CONTEXTIDR, read or write CP15 with:

MRC p15, 0, <Rd>, c13, c0, 1  ; Read CONTEXTIDR
MCR p15, 0, <Rd>, c13, c0, 1  ; Write CONTEXTIDR
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