4.2. Internal Coprocessor Instructions


The CP15 register map may change in later ARM processors. It is strongly recommend that you structure software so that any code accessing coprocessor 15 is contained in a single module. It can then be updated easily.

CP15 registers can only be accessed with MRC and MCR instructions in a Privileged mode. The instruction bit pattern of the MCR and MRC instructions is shown below.

Figure 4.1. MRC, MCR bit pattern

CDP, LDC and STC instructions, as well as unprivileged MRC and MCR instructions to CP15 cause the undefined instruction trap to be taken.

The CRn field of MRC and MCR instructions specifies the coprocessor register to access. The CRm field and opcode_2 fields are used to specify a particular action when addressing some registers.

In all instructions which access CP15:

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