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

Message ID 20200609104604.1594-2-stanimir.varbanov@linaro.org
State New
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  • [v3,1/7] Documentation: dynamic-debug: Add description of level bitmask
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Commit Message

Stanimir Varbanov June 9, 2020, 10:45 a.m.
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
+    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