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Linus Torvalds1da177e2005-04-16 15:20:36 -07001S390 Debug Feature
2==================
3
4files: arch/s390/kernel/debug.c
Randy Dunlap58cc8552009-01-06 14:42:42 -08005 arch/s390/include/asm/debug.h
Linus Torvalds1da177e2005-04-16 15:20:36 -07006
7Description:
8------------
9The goal of this feature is to provide a kernel debug logging API
10where log records can be stored efficiently in memory, where each component
11(e.g. device drivers) can have one separate debug log.
12One purpose of this is to inspect the debug logs after a production system crash
13in order to analyze the reason for the crash.
Matt LaPlantea2ffd272006-10-03 22:49:15 +020014If the system still runs but only a subcomponent which uses dbf fails,
Michael Holzheu66a464d2005-06-25 14:55:33 -070015it is possible to look at the debug logs on a live system via the Linux
16debugfs filesystem.
Linus Torvalds1da177e2005-04-16 15:20:36 -070017The debug feature may also very useful for kernel and driver development.
18
19Design:
20-------
21Kernel components (e.g. device drivers) can register themselves at the debug
22feature with the function call debug_register(). This function initializes a
23debug log for the caller. For each debug log exists a number of debug areas
24where exactly one is active at one time. Each debug area consists of contiguous
25pages in memory. In the debug areas there are stored debug entries (log records)
26which are written by event- and exception-calls.
27
28An event-call writes the specified debug entry to the active debug
29area and updates the log pointer for the active area. If the end
30of the active debug area is reached, a wrap around is done (ring buffer)
31and the next debug entry will be written at the beginning of the active
32debug area.
33
34An exception-call writes the specified debug entry to the log and
35switches to the next debug area. This is done in order to be sure
36that the records which describe the origin of the exception are not
37overwritten when a wrap around for the current area occurs.
38
Nicolas Kaiser2254f5a2006-12-04 15:40:23 +010039The debug areas themselves are also ordered in form of a ring buffer.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040When an exception is thrown in the last debug area, the following debug
41entries are then written again in the very first area.
42
43There are three versions for the event- and exception-calls: One for
44logging raw data, one for text and one for numbers.
45
46Each debug entry contains the following data:
47
48- Timestamp
49- Cpu-Number of calling task
50- Level of debug entry (0...6)
51- Return Address to caller
52- Flag, if entry is an exception or not
53
54The debug logs can be inspected in a live system through entries in
Michael Holzheu66a464d2005-06-25 14:55:33 -070055the debugfs-filesystem. Under the toplevel directory "s390dbf" there is
Linus Torvalds1da177e2005-04-16 15:20:36 -070056a directory for each registered component, which is named like the
Michael Holzheu66a464d2005-06-25 14:55:33 -070057corresponding component. The debugfs normally should be mounted to
Nicolas Kaiser2254f5a2006-12-04 15:40:23 +010058/sys/kernel/debug therefore the debug feature can be accessed under
Michael Holzheu66a464d2005-06-25 14:55:33 -070059/sys/kernel/debug/s390dbf.
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61The content of the directories are files which represent different views
62to the debug log. Each component can decide which views should be
63used through registering them with the function debug_register_view().
64Predefined views for hex/ascii, sprintf and raw binary data are provided.
65It is also possible to define other views. The content of
Michael Holzheu66a464d2005-06-25 14:55:33 -070066a view can be inspected simply by reading the corresponding debugfs file.
Linus Torvalds1da177e2005-04-16 15:20:36 -070067
Paolo Ornati670e9f32006-10-03 22:57:56 +020068All debug logs have an actual debug level (range from 0 to 6).
Linus Torvalds1da177e2005-04-16 15:20:36 -070069The default level is 3. Event and Exception functions have a 'level'
70parameter. Only debug entries with a level that is lower or equal
71than the actual level are written to the log. This means, when
72writing events, high priority log entries should have a low level
73value whereas low priority entries should have a high one.
Michael Holzheu66a464d2005-06-25 14:55:33 -070074The actual debug level can be changed with the help of the debugfs-filesystem
75through writing a number string "x" to the 'level' debugfs file which is
Linus Torvalds1da177e2005-04-16 15:20:36 -070076provided for every debug log. Debugging can be switched off completely
Michael Holzheu66a464d2005-06-25 14:55:33 -070077by using "-" on the 'level' debugfs file.
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
79Example:
80
Michael Holzheu66a464d2005-06-25 14:55:33 -070081> echo "-" > /sys/kernel/debug/s390dbf/dasd/level
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
83It is also possible to deactivate the debug feature globally for every
84debug log. You can change the behavior using 2 sysctl parameters in
85/proc/sys/s390dbf:
Matt LaPlante992caac2006-10-03 22:52:05 +020086There are currently 2 possible triggers, which stop the debug feature
87globally. The first possibility is to use the "debug_active" sysctl. If
Linus Torvalds1da177e2005-04-16 15:20:36 -070088set to 1 the debug feature is running. If "debug_active" is set to 0 the
89debug feature is turned off.
Nicolas Kaiser2254f5a2006-12-04 15:40:23 +010090The second trigger which stops the debug feature is a kernel oops.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091That prevents the debug feature from overwriting debug information that
92happened before the oops. After an oops you can reactivate the debug feature
93by piping 1 to /proc/sys/s390dbf/debug_active. Nevertheless, its not
Nicolas Kaiser2254f5a2006-12-04 15:40:23 +010094suggested to use an oopsed kernel in a production environment.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095If you want to disallow the deactivation of the debug feature, you can use
96the "debug_stoppable" sysctl. If you set "debug_stoppable" to 0 the debug
97feature cannot be stopped. If the debug feature is already stopped, it
98will stay deactivated.
99
100Kernel Interfaces:
101------------------
102
103----------------------------------------------------------------------------
Michael Holzheu66a464d2005-06-25 14:55:33 -0700104debug_info_t *debug_register(char *name, int pages, int nr_areas,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 int buf_size);
106
Michael Holzheu66a464d2005-06-25 14:55:33 -0700107Parameter: name: Name of debug log (e.g. used for debugfs entry)
108 pages: number of pages, which will be allocated per area
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 nr_areas: number of debug areas
110 buf_size: size of data area in each debug entry
111
112Return Value: Handle for generated debug area
113 NULL if register failed
114
115Description: Allocates memory for a debug log
116 Must not be called within an interrupt handler
117
Michael Holzheu9637c3f2008-04-17 07:46:18 +0200118----------------------------------------------------------------------------
119debug_info_t *debug_register_mode(char *name, int pages, int nr_areas,
120 int buf_size, mode_t mode, uid_t uid,
121 gid_t gid);
122
123Parameter: name: Name of debug log (e.g. used for debugfs entry)
124 pages: Number of pages, which will be allocated per area
125 nr_areas: Number of debug areas
126 buf_size: Size of data area in each debug entry
127 mode: File mode for debugfs files. E.g. S_IRWXUGO
128 uid: User ID for debugfs files. Currently only 0 is
129 supported.
130 gid: Group ID for debugfs files. Currently only 0 is
131 supported.
132
133Return Value: Handle for generated debug area
134 NULL if register failed
135
136Description: Allocates memory for a debug log
137 Must not be called within an interrupt handler
138
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139---------------------------------------------------------------------------
140void debug_unregister (debug_info_t * id);
141
142Parameter: id: handle for debug log
143
144Return Value: none
145
146Description: frees memory for a debug log
147 Must not be called within an interrupt handler
148
149---------------------------------------------------------------------------
150void debug_set_level (debug_info_t * id, int new_level);
151
152Parameter: id: handle for debug log
153 new_level: new debug level
154
155Return Value: none
156
157Description: Sets new actual debug level if new_level is valid.
158
159---------------------------------------------------------------------------
Michael Holzheu66a464d2005-06-25 14:55:33 -0700160void debug_stop_all(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
162Parameter: none
163
164Return Value: none
165
166Description: stops the debug feature if stopping is allowed. Currently
167 used in case of a kernel oops.
168
169---------------------------------------------------------------------------
170debug_entry_t* debug_event (debug_info_t* id, int level, void* data,
171 int length);
172
173Parameter: id: handle for debug log
174 level: debug level
175 data: pointer to data for debug entry
176 length: length of data in bytes
177
178Return Value: Address of written debug entry
179
180Description: writes debug entry to active debug area (if level <= actual
181 debug level)
182
183---------------------------------------------------------------------------
184debug_entry_t* debug_int_event (debug_info_t * id, int level,
185 unsigned int data);
186debug_entry_t* debug_long_event(debug_info_t * id, int level,
187 unsigned long data);
188
189Parameter: id: handle for debug log
190 level: debug level
191 data: integer value for debug entry
192
193Return Value: Address of written debug entry
194
195Description: writes debug entry to active debug area (if level <= actual
196 debug level)
197
198---------------------------------------------------------------------------
199debug_entry_t* debug_text_event (debug_info_t * id, int level,
200 const char* data);
201
202Parameter: id: handle for debug log
203 level: debug level
204 data: string for debug entry
205
206Return Value: Address of written debug entry
207
208Description: writes debug entry in ascii format to active debug area
209 (if level <= actual debug level)
210
211---------------------------------------------------------------------------
212debug_entry_t* debug_sprintf_event (debug_info_t * id, int level,
213 char* string,...);
214
215Parameter: id: handle for debug log
216 level: debug level
217 string: format string for debug entry
218 ...: varargs used as in sprintf()
219
220Return Value: Address of written debug entry
221
222Description: writes debug entry with format string and varargs (longs) to
223 active debug area (if level $<=$ actual debug level).
224 floats and long long datatypes cannot be used as varargs.
225
226---------------------------------------------------------------------------
227
228debug_entry_t* debug_exception (debug_info_t* id, int level, void* data,
229 int length);
230
231Parameter: id: handle for debug log
232 level: debug level
233 data: pointer to data for debug entry
234 length: length of data in bytes
235
236Return Value: Address of written debug entry
237
238Description: writes debug entry to active debug area (if level <= actual
239 debug level) and switches to next debug area
240
241---------------------------------------------------------------------------
242debug_entry_t* debug_int_exception (debug_info_t * id, int level,
243 unsigned int data);
244debug_entry_t* debug_long_exception(debug_info_t * id, int level,
245 unsigned long data);
246
247Parameter: id: handle for debug log
248 level: debug level
249 data: integer value for debug entry
250
251Return Value: Address of written debug entry
252
253Description: writes debug entry to active debug area (if level <= actual
254 debug level) and switches to next debug area
255
256---------------------------------------------------------------------------
257debug_entry_t* debug_text_exception (debug_info_t * id, int level,
258 const char* data);
259
260Parameter: id: handle for debug log
261 level: debug level
262 data: string for debug entry
263
264Return Value: Address of written debug entry
265
266Description: writes debug entry in ascii format to active debug area
267 (if level <= actual debug level) and switches to next debug
268 area
269
270---------------------------------------------------------------------------
271debug_entry_t* debug_sprintf_exception (debug_info_t * id, int level,
272 char* string,...);
273
274Parameter: id: handle for debug log
275 level: debug level
276 string: format string for debug entry
277 ...: varargs used as in sprintf()
278
279Return Value: Address of written debug entry
280
281Description: writes debug entry with format string and varargs (longs) to
282 active debug area (if level $<=$ actual debug level) and
283 switches to next debug area.
284 floats and long long datatypes cannot be used as varargs.
285
286---------------------------------------------------------------------------
287
288int debug_register_view (debug_info_t * id, struct debug_view *view);
289
290Parameter: id: handle for debug log
291 view: pointer to debug view struct
292
293Return Value: 0 : ok
294 < 0: Error
295
Michael Holzheu66a464d2005-06-25 14:55:33 -0700296Description: registers new debug view and creates debugfs dir entry
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297
298---------------------------------------------------------------------------
299int debug_unregister_view (debug_info_t * id, struct debug_view *view);
300
301Parameter: id: handle for debug log
302 view: pointer to debug view struct
303
304Return Value: 0 : ok
305 < 0: Error
306
Michael Holzheu66a464d2005-06-25 14:55:33 -0700307Description: unregisters debug view and removes debugfs dir entry
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
309
310
311Predefined views:
312-----------------
313
314extern struct debug_view debug_hex_ascii_view;
315extern struct debug_view debug_raw_view;
316extern struct debug_view debug_sprintf_view;
317
318Examples
319--------
320
321/*
322 * hex_ascii- + raw-view Example
323 */
324
325#include <linux/init.h>
326#include <asm/debug.h>
327
328static debug_info_t* debug_info;
329
330static int init(void)
331{
332 /* register 4 debug areas with one page each and 4 byte data field */
333
Michael Holzheu66a464d2005-06-25 14:55:33 -0700334 debug_info = debug_register ("test", 1, 4, 4 );
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 debug_register_view(debug_info,&debug_hex_ascii_view);
336 debug_register_view(debug_info,&debug_raw_view);
337
338 debug_text_event(debug_info, 4 , "one ");
339 debug_int_exception(debug_info, 4, 4711);
340 debug_event(debug_info, 3, &debug_info, 4);
341
342 return 0;
343}
344
345static void cleanup(void)
346{
347 debug_unregister (debug_info);
348}
349
350module_init(init);
351module_exit(cleanup);
352
353---------------------------------------------------------------------------
354
355/*
356 * sprintf-view Example
357 */
358
359#include <linux/init.h>
360#include <asm/debug.h>
361
362static debug_info_t* debug_info;
363
364static int init(void)
365{
366 /* register 4 debug areas with one page each and data field for */
367 /* format string pointer + 2 varargs (= 3 * sizeof(long)) */
368
Michael Holzheu66a464d2005-06-25 14:55:33 -0700369 debug_info = debug_register ("test", 1, 4, sizeof(long) * 3);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 debug_register_view(debug_info,&debug_sprintf_view);
371
372 debug_sprintf_event(debug_info, 2 , "first event in %s:%i\n",__FILE__,__LINE__);
373 debug_sprintf_exception(debug_info, 1, "pointer to debug info: %p\n",&debug_info);
374
375 return 0;
376}
377
378static void cleanup(void)
379{
380 debug_unregister (debug_info);
381}
382
383module_init(init);
384module_exit(cleanup);
385
386
387
Michael Holzheu66a464d2005-06-25 14:55:33 -0700388Debugfs Interface
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389----------------
390Views to the debug logs can be investigated through reading the corresponding
Michael Holzheu66a464d2005-06-25 14:55:33 -0700391debugfs-files:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392
393Example:
394
Michael Holzheu66a464d2005-06-25 14:55:33 -0700395> ls /sys/kernel/debug/s390dbf/dasd
396flush hex_ascii level pages raw
397> cat /sys/kernel/debug/s390dbf/dasd/hex_ascii | sort +1
Linus Torvalds1da177e2005-04-16 15:20:36 -070039800 00974733272:680099 2 - 02 0006ad7e 07 ea 4a 90 | ....
39900 00974733272:682210 2 - 02 0006ade6 46 52 45 45 | FREE
40000 00974733272:682213 2 - 02 0006adf6 07 ea 4a 90 | ....
40100 00974733272:682281 1 * 02 0006ab08 41 4c 4c 43 | EXCP
40201 00974733272:682284 2 - 02 0006ab16 45 43 4b 44 | ECKD
40301 00974733272:682287 2 - 02 0006ab28 00 00 00 04 | ....
40401 00974733272:682289 2 - 02 0006ab3e 00 00 00 20 | ...
40501 00974733272:682297 2 - 02 0006ad7e 07 ea 4a 90 | ....
40601 00974733272:684384 2 - 00 0006ade6 46 52 45 45 | FREE
40701 00974733272:684388 2 - 00 0006adf6 07 ea 4a 90 | ....
408
409See section about predefined views for explanation of the above output!
410
411Changing the debug level
412------------------------
413
414Example:
415
416
Michael Holzheu66a464d2005-06-25 14:55:33 -0700417> cat /sys/kernel/debug/s390dbf/dasd/level
Linus Torvalds1da177e2005-04-16 15:20:36 -07004183
Michael Holzheu66a464d2005-06-25 14:55:33 -0700419> echo "5" > /sys/kernel/debug/s390dbf/dasd/level
420> cat /sys/kernel/debug/s390dbf/dasd/level
Linus Torvalds1da177e2005-04-16 15:20:36 -07004215
422
423Flushing debug areas
424--------------------
425Debug areas can be flushed with piping the number of the desired
Michael Holzheu66a464d2005-06-25 14:55:33 -0700426area (0...n) to the debugfs file "flush". When using "-" all debug areas
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427are flushed.
428
429Examples:
430
4311. Flush debug area 0:
Michael Holzheu66a464d2005-06-25 14:55:33 -0700432> echo "0" > /sys/kernel/debug/s390dbf/dasd/flush
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433
4342. Flush all debug areas:
Michael Holzheu66a464d2005-06-25 14:55:33 -0700435> echo "-" > /sys/kernel/debug/s390dbf/dasd/flush
436
437Changing the size of debug areas
438------------------------------------
439It is possible the change the size of debug areas through piping
440the number of pages to the debugfs file "pages". The resize request will
441also flush the debug areas.
442
443Example:
444
445Define 4 pages for the debug areas of debug feature "dasd":
446> echo "4" > /sys/kernel/debug/s390dbf/dasd/pages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447
448Stooping the debug feature
449--------------------------
450Example:
451
4521. Check if stopping is allowed
453> cat /proc/sys/s390dbf/debug_stoppable
4542. Stop debug feature
455> echo 0 > /proc/sys/s390dbf/debug_active
456
457lcrash Interface
458----------------
459It is planned that the dump analysis tool lcrash gets an additional command
460's390dbf' to display all the debug logs. With this tool it will be possible
461to investigate the debug logs on a live system and with a memory dump after
462a system crash.
463
464Investigating raw memory
465------------------------
466One last possibility to investigate the debug logs at a live
467system and after a system crash is to look at the raw memory
468under VM or at the Service Element.
469It is possible to find the anker of the debug-logs through
470the 'debug_area_first' symbol in the System map. Then one has
471to follow the correct pointers of the data-structures defined
472in debug.h and find the debug-areas in memory.
473Normally modules which use the debug feature will also have
474a global variable with the pointer to the debug-logs. Following
475this pointer it will also be possible to find the debug logs in
476memory.
477
478For this method it is recommended to use '16 * x + 4' byte (x = 0..n)
479for the length of the data field in debug_register() in
480order to see the debug entries well formatted.
481
482
483Predefined Views
484----------------
485
486There are three predefined views: hex_ascii, raw and sprintf.
487The hex_ascii view shows the data field in hex and ascii representation
488(e.g. '45 43 4b 44 | ECKD').
489The raw view returns a bytestream as the debug areas are stored in memory.
490
491The sprintf view formats the debug entries in the same way as the sprintf
Matt LaPlantefff92892006-10-03 22:47:42 +0200492function would do. The sprintf event/exception functions write to the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493debug entry a pointer to the format string (size = sizeof(long))
494and for each vararg a long value. So e.g. for a debug entry with a format
495string plus two varargs one would need to allocate a (3 * sizeof(long))
496byte data area in the debug_register() function.
497
Michael Holzheuf64d04c2009-09-11 10:28:59 +0200498IMPORTANT: Using "%s" in sprintf event functions is dangerous. You can only
499use "%s" in the sprintf event functions, if the memory for the passed string is
500available as long as the debug feature exists. The reason behind this is that
501due to performance considerations only a pointer to the string is stored in
502the debug feature. If you log a string that is freed afterwards, you will get
503an OOPS when inspecting the debug feature, because then the debug feature will
504access the already freed memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505
506NOTE: If using the sprintf view do NOT use other event/exception functions
507than the sprintf-event and -exception functions.
508
509The format of the hex_ascii and sprintf view is as follows:
510- Number of area
511- Timestamp (formatted as seconds and microseconds since 00:00:00 Coordinated
512 Universal Time (UTC), January 1, 1970)
513- level of debug entry
514- Exception flag (* = Exception)
515- Cpu-Number of calling task
516- Return Address to caller
517- data field
518
519The format of the raw view is:
520- Header as described in debug.h
521- datafield
522
523A typical line of the hex_ascii view will look like the following (first line
524is only for explanation and will not be displayed when 'cating' the view):
525
526area time level exception cpu caller data (hex + ascii)
527--------------------------------------------------------------------------
52800 00964419409:440690 1 - 00 88023fe
529
530
531Defining views
532--------------
533
534Views are specified with the 'debug_view' structure. There are defined
Michael Holzheu66a464d2005-06-25 14:55:33 -0700535callback functions which are used for reading and writing the debugfs files:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536
537struct debug_view {
538 char name[DEBUG_MAX_PROCF_LEN];
539 debug_prolog_proc_t* prolog_proc;
540 debug_header_proc_t* header_proc;
541 debug_format_proc_t* format_proc;
542 debug_input_proc_t* input_proc;
543 void* private_data;
544};
545
546where
547
548typedef int (debug_header_proc_t) (debug_info_t* id,
549 struct debug_view* view,
550 int area,
551 debug_entry_t* entry,
552 char* out_buf);
553
554typedef int (debug_format_proc_t) (debug_info_t* id,
555 struct debug_view* view, char* out_buf,
556 const char* in_buf);
557typedef int (debug_prolog_proc_t) (debug_info_t* id,
558 struct debug_view* view,
559 char* out_buf);
560typedef int (debug_input_proc_t) (debug_info_t* id,
561 struct debug_view* view,
562 struct file* file, const char* user_buf,
563 size_t in_buf_size, loff_t* offset);
564
565
566The "private_data" member can be used as pointer to view specific data.
567It is not used by the debug feature itself.
568
Michael Holzheu66a464d2005-06-25 14:55:33 -0700569The output when reading a debugfs file is structured like this:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
571"prolog_proc output"
572
573"header_proc output 1" "format_proc output 1"
574"header_proc output 2" "format_proc output 2"
575"header_proc output 3" "format_proc output 3"
576...
577
Michael Holzheu66a464d2005-06-25 14:55:33 -0700578When a view is read from the debugfs, the Debug Feature calls the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579'prolog_proc' once for writing the prolog.
580Then 'header_proc' and 'format_proc' are called for each
581existing debug entry.
582
583The input_proc can be used to implement functionality when it is written to
Michael Holzheu66a464d2005-06-25 14:55:33 -0700584the view (e.g. like with 'echo "0" > /sys/kernel/debug/s390dbf/dasd/level).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585
586For header_proc there can be used the default function
Paolo Ornati670e9f32006-10-03 22:57:56 +0200587debug_dflt_header_fn() which is defined in debug.h.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588and which produces the same header output as the predefined views.
589E.g:
59000 00964419409:440761 2 - 00 88023ec
591
592In order to see how to use the callback functions check the implementation
593of the default views!
594
595Example
596
597#include <asm/debug.h>
598
599#define UNKNOWNSTR "data: %08x"
600
601const char* messages[] =
602{"This error...........\n",
603 "That error...........\n",
604 "Problem..............\n",
605 "Something went wrong.\n",
606 "Everything ok........\n",
607 NULL
608};
609
610static int debug_test_format_fn(
611 debug_info_t * id, struct debug_view *view,
612 char *out_buf, const char *in_buf
613)
614{
615 int i, rc = 0;
616
617 if(id->buf_size >= 4) {
618 int msg_nr = *((int*)in_buf);
619 if(msg_nr < sizeof(messages)/sizeof(char*) - 1)
620 rc += sprintf(out_buf, "%s", messages[msg_nr]);
621 else
622 rc += sprintf(out_buf, UNKNOWNSTR, msg_nr);
623 }
624 out:
625 return rc;
626}
627
628struct debug_view debug_test_view = {
629 "myview", /* name of view */
630 NULL, /* no prolog */
631 &debug_dflt_header_fn, /* default header for each entry */
632 &debug_test_format_fn, /* our own format function */
633 NULL, /* no input function */
634 NULL /* no private data */
635};
636
637=====
638test:
639=====
640debug_info_t *debug_info;
641...
642debug_info = debug_register ("test", 0, 4, 4 ));
643debug_register_view(debug_info, &debug_test_view);
644for(i = 0; i < 10; i ++) debug_int_event(debug_info, 1, i);
645
Michael Holzheu66a464d2005-06-25 14:55:33 -0700646> cat /sys/kernel/debug/s390dbf/test/myview
Linus Torvalds1da177e2005-04-16 15:20:36 -070064700 00964419734:611402 1 - 00 88042ca This error...........
64800 00964419734:611405 1 - 00 88042ca That error...........
64900 00964419734:611408 1 - 00 88042ca Problem..............
65000 00964419734:611411 1 - 00 88042ca Something went wrong.
65100 00964419734:611414 1 - 00 88042ca Everything ok........
65200 00964419734:611417 1 - 00 88042ca data: 00000005
65300 00964419734:611419 1 - 00 88042ca data: 00000006
65400 00964419734:611422 1 - 00 88042ca data: 00000007
65500 00964419734:611425 1 - 00 88042ca data: 00000008
65600 00964419734:611428 1 - 00 88042ca data: 00000009