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Diffstat (limited to 'Documentation/trace/events.rst')
| -rw-r--r-- | Documentation/trace/events.rst | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst index f792b1959a33..2a5aa48eff6c 100644 --- a/Documentation/trace/events.rst +++ b/Documentation/trace/events.rst @@ -589,8 +589,19 @@ name:: { .type = "int", .name = "my_int_field" }, }; -See synth_field_size() for available types. If field_name contains [n] -the field is considered to be an array. +See synth_field_size() for available types. + +If field_name contains [n], the field is considered to be a static array. + +If field_names contains[] (no subscript), the field is considered to +be a dynamic array, which will only take as much space in the event as +is required to hold the array. + +Because space for an event is reserved before assigning field values +to the event, using dynamic arrays implies that the piecewise +in-kernel API described below can't be used with dynamic arrays. The +other non-piecewise in-kernel APIs can, however, be used with dynamic +arrays. If the event is created from within a module, a pointer to the module must be passed to synth_event_create(). This will ensure that the |