trace/coresight/coresight-config.rst

26 This section introduces the basic concepts of a CoreSight system configuration.
38 CoreSight device is registered with the configuration manager.
49 A feature is enabled as part of a configuration being enabled on the system.
76 A configuration defines a set of features that are to be used in a trace
77 session where the configuration is selected. For any trace session only one
78 configuration may be selected.
81 to support system configuration. A configuration may select features to be
85 As with the feature, a descriptor is used to define the configuration.
86 This will define the features that must be enabled as part of the configuration
95 that the configuration uses. The number of values in a single preset set, equals
96 the sum of parameter values in the features used by the configuration.
98 e.g. a configuration consists of 3 features, one has 2 parameters, one has
102 Presets are optionally defined by the configuration, up to 15 can be defined.
110 The following steps take place in the operation of a configuration.
112 1) In this example, the configuration is 'autofdo', which has an
115 2) The configuration is enabled. For example 'perf' may select the
116    configuration as part of its command line::
120    which will enable the 'autofdo' configuration.
123    trace is enabled,  the configuration manager will check if the ETMv4
124    has a feature that relates to the currently active configuration.
130 5) At the end of the perf session, the configuration will be disabled.
150 The system has the configuration 'autofdo' built in. It may be examined as
173 The 'enable' and 'preset' files allow the control of a configuration when
176 The features referenced by the configuration can be examined in the features
212 The configurations loaded into the CoreSight configuration management are
222 a hash of the configuration name.
232 The 'autofdo' configuration may be selected on the perf command line::
246 Coresight can be controlled using sysfs. When this is in use then a configuration
249 In a configuration there are 'enable' and 'preset' files.
251 To enable a configuration for use with sysfs::
263 This will select preset3 for the configuration.
267 Note that the active sysfs configuration is a global parameter, therefore
268 only a single configuration can be active for sysfs at any one time.
269 Attempting to enable a second configuration will result in an error.
270 Additionally, attempting to disable the configuration while in use will
273 The use of the active configuration by sysfs is independent of the configuration
283 An example of a custom configuration is found in ./samples/coresight.
285 This creates a new configuration that uses the existing built in
288 When the module is loaded, then the configuration appears in the configfs
289 file system and is selectable in the same way as the built in configuration