Documentation/admin-guide/dynamic-debug-howto.rst

9 debug-print code to obtain additional kernel information.
22    - source filename
23    - function name
24    - line number (including ranges of line numbers)
25    - module name
26    - format string
27    - class name (as known/declared by each module)
29 NOTE: To actually get the debug-print output on the console, you may
32 Documentation/admin-guide/kernel-parameters.rst.
39   :#> head -n7 /proc/dynamic_debug/control
48 The 3rd space-delimited column shows the current flags, preceded by
60   :#> ddcmd '-p; module main func run* +p'
75 also under the mount-dir, typically ``/sys/kernel/debug/``.
83   :#> ddcmd file svcsock.c line 1603 +p
84   :#> ddcmd "file svcsock.c line 1603 +p"
85   :#> ddcmd '  file   svcsock.c     line  1603 +p  '
95   :#> cat query-batch-file > /proc/dynamic_debug/control
106   command ::= match-spec* flags-spec
108 The match-spec's select *prdbgs* from the catalog, upon which to apply
109 the flags-spec, all constraints are ANDed together.  An absent keyword
117   match-spec ::= 'func' string |
122 		 'line' line-range
124   line-range ::= lineno |
125 		 '-'lineno |
126 		 lineno'-' |
127 		 lineno'-'lineno
129   lineno ::= unsigned-int
133   ``line-range`` cannot contain space, e.g.
134   "1-30" is valid range but "1 - 30" is not.
140     The given string is compared against the function name
147     The given string is compared against either the src-root relative
155 	file inode.c:1-100	# parse :tail as a line-range (above)
158     The given string is compared against the module name
159     of each callsite.  The module name is the string as
161     suffix and with ``-`` changed to ``_``.  Examples::
190 	class JUNK		# silent non-match
193 line
194     The given line number or range of line numbers is compared
195     against the line number of each ``pr_debug()`` callsite.  A single
196     line number matches the callsite line number exactly.  A
197     range of line numbers matches any callsite between the first
198     and last line number inclusive.  An empty first number means
199     the first line in the file, an empty last line number means the
200     last line number in the file.  Examples::
202 	line 1603           // exactly line 1603
203 	line 1600-1605      // the six lines from line 1600 to line 1605
204 	line -1605          // the 1605 lines from line 1 to line 1605
205 	line 1600-          // all lines from line 1600 to the end of the file
211   -    remove the given flags
220   Decorator flags add to the message-prefix, in order:
222   m    Include module name
223   f    Include the function name
224   s    Include the source file name
225   l    Include line number
230 Note the regexp ``^[-+=][fslmpt_]+$`` matches a flags specification.
231 To clear all flags at once, use ``=_`` or ``-fslmpt``.
237 To activate debug messages for core code and built-in modules during
257 If ``foo`` module is not built-in, ``foo.dyndbg`` will still be processed at
289 ``foo`` is extracted from the param-name, and applied to each query in
290 ``QUERY``, and only 1 match-spec of each type is allowed.
294 - modules do not need to define it explicitly
295 - every module gets it tacitly, whether they use pr_debug or not
296 - it doesn't appear in ``/sys/module/$module/parameters/``
299 For ``CONFIG_DYNAMIC_DEBUG`` kernels, any settings given at boot-time (or
300 enabled by ``-DDEBUG`` flag during compilation) can be disabled later via
303    echo "module module_name -p" > /proc/dynamic_debug/control
310   // enable the message at line 1603 of file svcsock.c
311   :#> ddcmd 'file svcsock.c line 1603 +p'
323   :#> ddcmd 'func svc_process -p'
337   // boot-args example, with newlines and comments for readability
338   Kernel command line: ...
359 debug and add ``ccflags := -DDYNAMIC_DEBUG_MODULE`` into the Makefile of any
374 Otherwise, they are off by default; ``ccflags += -DDEBUG`` or