[PATCH v3 1/7] Documentation: dynamic-debug: Add description of level bitmask

Stanimir Varbanov
2020-06-09T10:47:48Z

This adds description of the level bitmask feature.

Cc: Jonathan Corbet <corbet@lwn.net> (maintainer:DOCUMENTATION)

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
---
Documentation/admin-guide/dynamic-debug-howto.rst | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 0dc2eb8e44e5..c2b751fc8a17 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -208,6 +208,12 @@ line
line -1605 // the 1605 lines from line 1 to line 1605
line 1600- // all lines from line 1600 to the end of the file

+level
+ The given level will be a bitmask ANDed with the level of the each ``pr_debug()``
+ callsite. This will allow to group debug messages and show only those of the
+ same level. The -p flag takes precedence over the given level. Note that we can
+ have up to five groups of debug messages.
+
The flags specification comprises a change operation followed
by one or more flag characters. The change operation is one
of the characters::
@@ -346,6 +352,10 @@ Examples
// add module, function to all enabled messages
nullarbor:~ # echo -n '+mf' > <debugfs>/dynamic_debug/control

+ // enable all messages in file with 0x01 level bitmask
+ nullarbor:~ # echo -n 'file foo.c level 0x01 +p' >
+ <debugfs>/dynamic_debug/control
+
// boot-args example, with newlines and comments for readability
Kernel command line: ...
// see whats going on in dyndbg=value processing
--
2.17.1