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| author | Masami Hiramatsu <mhiramat@kernel.org> | 2020-09-10 15:39:27 +0300 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-09-22 04:06:04 +0300 |
| commit | fd264ce96c382bc2e36eb1f49ac45c5980650244 (patch) | |
| tree | 6cba171396e64eea548b421115943c2a40326adc /Documentation/trace | |
| parent | ba0fbfbb21cd90d51e4f6668ee8397e810818028 (diff) | |
| download | linux-fd264ce96c382bc2e36eb1f49ac45c5980650244.tar.xz | |
Documentation: tracing: Add the startup timing of boot-time tracing
Add the note about when to start the boot-time tracing.
This will be needed for the people who wants to trace
earlier boot sequence.
Link: https://lkml.kernel.org/r/159974156678.478751.10215894815285734481.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/boottime-trace.rst | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst index ab3bfd67197c..89b64334929b 100644 --- a/Documentation/trace/boottime-trace.rst +++ b/Documentation/trace/boottime-trace.rst @@ -120,6 +120,20 @@ instance node, but those are also visible from other instances. So please take care for event name conflict. +When to Start +============= + +All boot-time tracing options starting with ``ftrace`` will be enabled at the +end of core_initcall. This means you can trace the events from postcore_initcall. +Most of the subsystems and architecture dependent drivers will be initialized +after that (arch_initcall or subsys_initcall). Thus, you can trace those with +boot-time tracing. +If you want to trace events before core_initcall, you can use the options +starting with ``kernel``. Some of them will be enabled eariler than the initcall +processing (for example,. ``kernel.ftrace=function`` and ``kernel.trace_event`` +will start before the initcall.) + + Examples ======== |