Update instrumentation/events README file

[lttng-modules.git] / instrumentation / events / README

* Workflow for updating patches from newer kernel:

Diff mainline/ and lttng-module/ directories.

Pull the new headers from mainline kernel to mainline/.
Copy them into lttng-modules.
Apply diff. Fix conflicts.


* Workflow to add new Tracepoint instrumentation to newer kernel,
  and add support for it into LTTng:

a) instrument the kernel with new trace events headers. If you want that
   instrumentation distributed, you will have to push those changes into
   the upstream Linux kernel first,
b) copy those headers into lttng mainline/ directory,
c) look at a diff from other headers between mainline/ and 
   lttng/, and use that as a recipe to create a new lttng/
   header from the mainline/ header,
d) create a new file in probes/ for the new trace event header you added,
e) add it to probes/Makefile,
f) build, make modules_install,
g) don't forget to load that new module too.

Currently, LTTng policy is to only accept headers derived from trace
event headers accepted into the Linux kernel upstream for tracepoints
related to upstream kernel instrumentation.