3.6.1. Resource identification

A resource identifier is seven bits:

Resource encoding

The resource encoding is given in Table 3.88.

Table 3.88. Resource encodings

Bits

Defined in ETM architecture versions

Description

[6:4]

v1.0

Resource type

[3:0]

v1.0

Resource index


Table 3.89 defines the available resource types and shows the bit encodings used to identify them.

Table 3.89. Resource identification encoding

Resource type (bits [6:4])

Index range (bits [3:0])

Description of resource type

b000

0-15

Single address comparator 1-16.

b001

0-7

Address range comparator 1-8.

Represents the range between two single address comparators.

b0018-11

Instrumentation resource 1-4.

Software-controlled resources. See Instrumentation resources, from ETMv3.3.

Only available in ETMv3.3 and later.

b010

0-7

EmbeddedICE module watchpoint comparators 1-8.

It is implementation defined whether an ETM supports EmbeddedICE watchpoint comparators. If it does:

  • In ETMv3.3 and earlier, two watchpoint comparators are implemented, using index values 0 and 1.

  • In ETMv3.4 and later, the number of watchpoint comparators is specified in the ETMCCER. The maximum number is eight, and the comparators use index values from 0 up to a maximum of 7.

b011

0-15

Memory map decodes 1-16.

b100

0-3

Counter 1-4 at zero.

b101

0-2

3-7

8-10

11

12-14

15

Sequencer in states 1-3.

Reserved.

Context ID comparator 1-3, ETMv2.0 and later.

VMID comparator, ETMv3.5

Reserved.

Trace start/stop resource, ETMv2.0 and later.

b110

0-3

4-7

8-11

12

13

14

15

External inputs 1-4.

Reserved.

Extended external input selectors 1-4, ETMv3.1 and later.

Reserved.

Processor is in Non-secure state.

Trace prohibited by processor.

Hard-wired input, always true.

b111

-

Reserved.


Note

  • Valid range encodings between 0 and 15 refer to resource IDs 1-16.

  • When a particular resource is active, this means that its output is a logical 1.

In ETMv3.5, if an invalid resource is programmed, such as one that is architecturally Reserved or a resource that is not supported by the specific implementation, the read value returned is unknown and the behavior of the event is unpredictable.

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