2.8.1. Terms used in this section

In this section, the following terms are used with the specific meanings given:

Access address

This is the data address accessed by the processor.

Access size

This is the size of the data access made by the processor. The size is word, halfword or byte. Multiple word LSM accesses are traced as a sequence of word accesses.

Access value

This is the value of the data accessed at the access address. It depends on the access size, for example for a byte access the access value is 8 bits of data.

Comparison address

This is the address configured in the comparator registers. It can be a single address, programmed into a single ETMACVR, or an address range specified by a pair of ETMACVRs.

The ETMACTR, or ETMACTRs, associated with the comparison are programmed for data value comparisons.

For more information see About the address comparator registers.

Comparison size

This is the size of the required comparison, as defined by the Comparison access size field of the ETMACTR for the comparison. For more information see Comparator access size and Address Comparator Access Type Registers, ETMACTRn.

When the Comparison size is halfword or byte, from ETMv3.3 the appropriate ETMDCMR must have the same mask value set in each byte or halfword, as described in this section.


This is a significant change from how the ETMDCMR is programmed in earlier ETM versions:

  • In ETMv1, unused byte lanes must be masked out, based on the comparison size and the bottom bits of the ETMACVR.

  • In ETM versions 2.0 to 3.2, the register must be set to mask out the unwanted area of the comparison. For example, if you want to compare a byte at address 0x2000, bits [31:8] of the ETMDCMR must all be set to 1.

For more information see Operation of data value comparators, in ETMv3.2 and earlier.

For more information about comparison size, see Data Comparator Mask Registers, ETMDCMRn.

Comparison value

This is the value to be used for the data comparison, defined by programming the ETMDCVR. See Data Comparator Value Registers, ETMDCVRn. This is a 32-bit register, however the value programmed into the register must match the comparison size.

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