Documentation/trace/user_events.rst

2 user_events: User-based Event Tracing
8 --------
10 that can be viewed via existing tools, such as ftrace and perf.
18 tools that can read trace_events (such as ftrace and perf). The registration
31 -----------
39         /* Input: Size of the user_reg structure being used */
40         __u32 size;
45         /* Input: Enable size in bytes at address */
63 + size: This must be set to sizeof(struct user_reg).
68 + enable_size: The size of the value specified by enable_addr.
69   This must be 4 (32-bit) or 8 (64-bit). 64-bit values are only allowed to be
70   used on 64-bit kernels, however, 32-bit can be used on all kernels.
74   support for lower versions of the kernel. If a flag is not supported -EINVAL
92 or perf record -e user_events:[name] when attaching/recording.
96 future to change the subsystem name per-process to accommodate event isolation.
112   type name [size]
117 **NOTE:** *Long is not supported since size can vary between user and kernel.*
119 The size is only valid for types that start with a struct prefix.
133 --------
143 **NOTE:** By default events will auto-delete when there are no references left
147 -------------
157         /* Input: Size of the user_unreg structure being used */
158         __u32 size;
175 + size: This must be set to sizeof(struct user_unreg).
188 ------
213 If a user enables the user event via ftrace, the output would change to this::
215   test # Used by ftrace
221 ------------
227 payload of the event. Then the data would have to be 8 bytes (2 ints) in size,
263 ------------