path: root/Documentation
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authorAnton Vorontsov <anton.vorontsov@linaro.org>2012-07-17 14:26:15 -0700
committerAnton Vorontsov <anton.vorontsov@linaro.org>2012-09-06 22:16:58 -0700
commit65f8c95e46a1827ae8bbc52a817ea308dd7d65ae (patch)
treeadc856e8b50441b055350d8f1d83e3f641c77456 /Documentation
parentb4a871bce619dc5ca03cc6c78e1c467ceacb8e7e (diff)
pstore/ftrace: Convert to its own enable/disable debugfs knob
With this patch we no longer reuse function tracer infrastructure, now we register our own tracer back-end via a debugfs knob. It's a bit more code, but that is the only downside. On the bright side we have: - Ability to make persistent_ram module removable (when needed, we can move ftrace_ops struct into a module). Note that persistent_ram is still not removable for other reasons, but with this patch it's just one thing less to worry about; - Pstore part is more isolated from the generic function tracer. We tried it already by registering our own tracer in available_tracers, but that way we're loosing ability to see the traces while we record them to pstore. This solution is somewhere in the middle: we only register "internal ftracer" back-end, but not the "front-end"; - When there is only pstore tracing enabled, the kernel will only write to the pstore buffer, omitting function tracer buffer (which, of course, still can be enabled via 'echo function > current_tracer'). Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Diffstat (limited to 'Documentation')
1 files changed, 1 insertions, 3 deletions
diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt
index 197ad59ab9bf..69b3cac4749d 100644
--- a/Documentation/ramoops.txt
+++ b/Documentation/ramoops.txt
@@ -102,9 +102,7 @@ related hangs. The functions call chain log is stored in a "ftrace-ramoops"
file. Here is an example of usage:
# mount -t debugfs debugfs /sys/kernel/debug/
- # cd /sys/kernel/debug/tracing
- # echo function > current_tracer
- # echo 1 > options/func_pstore
+ # echo 1 > /sys/kernel/debug/pstore/record_ftrace
# reboot -f
# mount -t pstore pstore /mnt/

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