2 .\" Mach Operating System
3 .\" Copyright (c) 1991,1990 Carnegie Mellon University
4 .\" Copyright (c) 2007 Robert N. M. Watson
5 .\" All Rights Reserved.
7 .\" Permission to use, copy, modify and distribute this software and its
8 .\" documentation is hereby granted, provided that both the copyright
9 .\" notice and this permission notice appear in all copies of the
10 .\" software, derivative works or modified versions, and any portions
11 .\" thereof, and that both notices appear in supporting documentation.
13 .\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
14 .\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
15 .\" ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17 .\" Carnegie Mellon requests users of this software to return to
19 .\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
20 .\" School of Computer Science
21 .\" Carnegie Mellon University
22 .\" Pittsburgh PA 15213-3890
24 .\" any improvements or extensions that they make and grant Carnegie Mellon
25 .\" the rights to redistribute these changes.
27 .\" changed a \# to #, since groff choked on it.
31 .\" Revision 1.1 1993/07/15 18:41:02 brezak
34 .\" Revision 2.6 92/04/08 08:52:57 rpd
36 .\" [92/01/17 14:19:22 jsb]
37 .\" Changes for OSF debugger modifications.
40 .\" Revision 2.5 91/06/25 13:50:22 rpd
41 .\" Added some watchpoint explanation.
44 .\" Revision 2.4 91/06/17 15:47:31 jsb
45 .\" Added documentation for continue/c, match, search, and watchpoints.
46 .\" I've not actually explained what a watchpoint is; maybe Rich can
47 .\" do that (hint, hint).
48 .\" [91/06/17 10:58:08 jsb]
50 .\" Revision 2.3 91/05/14 17:04:23 mrt
51 .\" Correcting copyright
53 .\" Revision 2.2 91/02/14 14:10:06 mrt
54 .\" Changed to new Mach copyright
55 .\" [91/02/12 18:10:12 mrt]
57 .\" Revision 2.2 90/08/30 14:23:15 dbg
63 .Dd September 30, 2013
68 .Nd interactive kernel debugger
70 In order to enable kernel debugging facilities include:
71 .Bd -ragged -offset indent
76 To prevent activation of the debugger on kernel
78 .Bd -ragged -offset indent
79 .Cd options KDB_UNATTENDED
82 In order to print a stack trace of the current thread on the console
84 .Bd -ragged -offset indent
88 To print the numerical value of symbols in addition to the symbolic
89 representation, define:
90 .Bd -ragged -offset indent
91 .Cd options DDB_NUMSYM
96 backend, so that remote debugging with
99 .Bd -ragged -offset indent
105 kernel debugger is an interactive debugger with a syntax inspired by
107 If linked into the running kernel,
108 it can be invoked locally with the
112 The debugger is also invoked on kernel
115 .Va debug.debugger_on_panic
117 MIB variable is set non-zero,
123 The current location is called
128 a hexadecimal format at a prompt.
135 to the address of the last line
136 examined or the last location modified, and set
139 the next location to be examined or changed.
140 Other commands do not change
147 The general command syntax is:
148 .Ar command Ns Op Li / Ns Ar modifier
149 .Ar address Ns Op Li , Ns Ar count
151 A blank line repeats the previous command from the address
154 count 1 and no modifiers.
167 to be 1 for printing commands or infinity for stack traces.
171 debugger has a pager feature (like the
175 If an output line exceeds the number set in the
177 variable, it displays
179 and waits for a response.
180 The valid responses for it are:
182 .Bl -tag -compact -width ".Li SPC"
188 abort the current command, and return to the command input mode
193 provides a small (currently 10 items) command history, and offers
196 command line editing capabilities.
200 control keys, the usual
202 arrow keys may be used to
203 browse through the history buffer, and move the cursor within the
206 .Bl -tag -width indent -compact
209 Display the addressed locations according to the formats in the modifier.
210 Multiple modifier formats display multiple locations.
211 If no format is specified, the last format specified for this command
214 The format characters are:
215 .Bl -tag -compact -width indent
217 look at by bytes (8 bits)
219 look at by half words (16 bits)
221 look at by long words (32 bits)
223 look at by quad words (64 bits)
225 print the location being displayed
227 print the location with a line number if possible
229 display in unsigned hex
231 display in signed hex
233 display in unsigned octal
235 display in signed decimal
237 display in unsigned decimal
239 display in current radix, signed
241 display low 8 bits as a character.
242 Non-printing characters are displayed as an octal escape code (e.g.,
245 display the null-terminated string at the location.
246 Non-printing characters are displayed as octal escapes.
248 display in unsigned hex with character dump at the end of each line.
249 The location is also displayed in hex at the beginning of each line.
251 display as an instruction
253 display as an instruction with possible alternate formats depending on the
254 machine, but none of the supported architectures have an alternate format.
256 display a symbol name for the pointer stored at the address
263 command with the last specified parameters to it
264 except that the next address displayed by it is used as the start address.
270 command with the last specified parameters to it
271 except that the last start address subtracted by the size displayed by it
272 is used as the start address.
274 .It Ic print Ns Op Li / Ns Cm acdoruxz
275 .It Ic p Ns Op Li / Ns Cm acdoruxz
278 according to the modifier character (as described above for
281 .Cm a , x , z , o , d , u , r ,
284 If no modifier is specified, the last one specified to it is used.
287 can be a string, in which case it is printed as it is.
289 .Bd -literal -offset indent
290 print/x "eax = " $eax "\enecx = " $ecx "\en"
294 .Bd -literal -offset indent
300 .Ic write Ns Op Li / Ns Cm bhl
301 .Ar addr expr1 Op Ar expr2 ...
304 .Ic w Ns Op Li / Ns Cm bhl
305 .Ar addr expr1 Op Ar expr2 ...
307 Write the expressions specified after
309 on the command line at succeeding locations starting with
311 The write unit size can be specified in the modifier with a letter
317 (long word) respectively.
319 long word is assumed.
322 since there is no delimiter between expressions, strange
324 It is best to enclose each expression in parentheses.
326 .It Ic set Li $ Ns Ar variable Oo Li = Oc Ar expr
327 Set the named variable or register with the value of
329 Valid variable names are described below.
331 .It Ic break Ns Op Li / Ns Cm u
332 .It Ic b Ns Op Li / Ns Cm u
337 is supplied, continues
339 \- 1 times before stopping at the
341 If the break point is set, a break point number is
344 This number can be used in deleting the break point
345 or adding conditions to it.
349 modifier is specified, this command sets a break point in user
353 option, the address is considered to be in the kernel
354 space, and a wrong space address is rejected with an error message.
355 This modifier can be used only if it is supported by machine dependent
359 If a user text is shadowed by a normal user space debugger,
360 user space break points may not work correctly.
362 point at the low-level code paths may also cause strange behavior.
364 .It Ic delete Ar addr
366 .It Ic delete Li # Ns Ar number
367 .It Ic d Li # Ns Ar number
368 Delete the break point.
369 The target break point can be specified by a
370 break point number with
374 specified in the original
378 .It Ic watch Ar addr Ns Li , Ns Ar size
379 Set a watchpoint for a region.
380 Execution stops when an attempt to modify the region occurs.
383 argument defaults to 4.
384 If you specify a wrong space address, the request is rejected
385 with an error message.
388 Attempts to watch wired kernel memory
389 may cause unrecoverable error in some systems such as i386.
390 Watchpoints on user addresses work best.
392 .It Ic hwatch Ar addr Ns Li , Ns Ar size
393 Set a hardware watchpoint for a region if supported by the
395 Execution stops when an attempt to modify the region occurs.
398 argument defaults to 4.
401 The hardware debug facilities do not have a concept of separate
402 address spaces like the watch command does.
405 for setting watchpoints on kernel address locations only, and avoid
406 its use on user mode address spaces.
408 .It Ic dhwatch Ar addr Ns Li , Ns Ar size
409 Delete specified hardware watchpoint.
411 .It Ic step Ns Op Li / Ns Cm p
412 .It Ic s Ns Op Li / Ns Cm p
415 times (the comma is a mandatory part of the syntax).
418 modifier is specified, print each instruction at each step.
419 Otherwise, only print the last instruction.
422 depending on machine type, it may not be possible to
423 single-step through some low-level code paths or user space code.
424 On machines with software-emulated single-stepping (e.g., pmax),
425 stepping through code executed by interrupt handlers will probably
428 .It Ic continue Ns Op Li / Ns Cm c
429 .It Ic c Ns Op Li / Ns Cm c
430 Continue execution until a breakpoint or watchpoint.
433 modifier is specified, count instructions while executing.
434 Some machines (e.g., pmax) also count loads and stores.
437 when counting, the debugger is really silently single-stepping.
438 This means that single-stepping on low-level code may cause strange
441 .It Ic until Ns Op Li / Ns Cm p
442 Stop at the next call or return instruction.
445 modifier is specified, print the call nesting depth and the
446 cumulative instruction count at each call or return.
448 only print when the matching return is hit.
450 .It Ic next Ns Op Li / Ns Cm p
451 .It Ic match Ns Op Li / Ns Cm p
452 Stop at the matching return instruction.
455 modifier is specified, print the call nesting depth and the
456 cumulative instruction count at each call or return.
457 Otherwise, only print when the matching return is hit.
460 .Ic trace Ns Op Li / Ns Cm u
465 .Ic t Ns Op Li / Ns Cm u
470 .Ic where Ns Op Li / Ns Cm u
475 .Ic bt Ns Op Li / Ns Cm u
482 option traces user space; if omitted,
486 The optional argument
488 is the number of frames to be traced.
491 is omitted, all frames are printed.
494 User space stack trace is valid
495 only if the machine dependent code supports it.
498 .Ic search Ns Op Li / Ns Cm bhl
506 This command might fail in interesting
507 ways if it does not find the searched-for value.
510 does not always recover from touching bad memory.
513 argument limits the search.
520 Prints the thread address for a thread kernel-mode stack of which contains the
522 If the thread is not found, search the thread stack cache and prints the
523 cached stack address.
524 Otherwise, prints nothing.
526 .It Ic show Cm all procs Ns Op Li / Ns Cm m
527 .It Ic ps Ns Op Li / Ns Cm m
528 Display all process information.
529 The process information may not be shown if it is not
530 supported in the machine, or the bottom of the stack of the
531 target process is not in the main memory at that time.
534 modifier will alter the display to show VM map
535 addresses for the process and not show other information.
538 .It Ic show Cm all ttys
539 Show all TTY's within the system.
542 but also includes the address of the TTY structure.
545 .It Ic show Cm allchains
546 Show the same information like "show lockchain" does, but
547 for every thread in the system.
550 .It Ic show Cm alllocks
551 Show all locks that are currently held.
552 This command is only available if
554 is included in the kernel.
557 .It Ic show Cm allpcpu
558 The same as "show pcpu", but for every CPU present in the system.
561 .It Ic show Cm allrman
562 Show information related with resource management, including
563 interrupt request lines, DMA request lines, I/O ports and I/O memory
568 Dump data about APIC IDT vector mappings.
571 .It Ic show Cm breaks
572 Show breakpoints set with the "break" command.
575 .It Ic show Cm buffer
576 Show buffer structure of
579 Such a structure is used within the
581 kernel for the I/O subsystem
583 For an exact interpretation of the output, please see the
588 .It Ic show Cm cbstat
589 Show brief information about the TTY subsystem.
593 Without argument, show the list of all created cdev's, consisting of devfs
594 node name and struct cdev address.
595 When address of cdev is supplied, show some internal devfs state of the cdev.
598 .It Ic show Cm conifhk
599 Lists hooks currently waiting for completion in
600 run_interrupt_driven_config_hooks().
603 .It Ic show Cm cpusets
604 Print numbered root and assigned CPU affinity sets.
610 .It Ic show Cm cyrixreg
611 Show registers specific to the Cyrix processor.
614 .It Ic show Cm domain Ar addr
615 Print protocol domain structure
621 header file for more details on the exact meaning of the structure fields.
624 .It Ic show Cm ffs Op Ar addr
625 Show brief information about ffs mount at the address
627 if argument is given.
628 Otherwise, provides the summary about each ffs mount.
631 .It Ic show Cm file Ar addr
632 Show information about the file structure
639 Show information about every file structure in the system.
642 .It Ic show Cm freepages
643 Show the number of physical pages in each of the free lists.
646 .It Ic show Cm geom Op Ar addr
649 argument is not given, displays the entire GEOM topology.
652 is given, displays details about the given GEOM object (class, geom,
653 provider or consumer).
658 The first column specifies the IDT vector.
659 The second one is the name of the interrupt/trap handler.
660 Those functions are machine dependent.
663 .It Ic show Cm inodedeps Op Ar addr
664 Show brief information about each inodedep structure.
667 is given, only inodedeps belonging to the fs located at the
668 supplied address are shown.
671 .It Ic show Cm inpcb Ar addr
672 Show information on IP Control Block
679 Dump information about interrupt handlers.
682 .It Ic show Cm intrcnt
683 Dump the interrupt statistics.
687 Show interrupt lines and their respective kernel threads.
696 shows, also list kernel internal details.
700 Show information from the local APIC registers for this CPU.
703 .It Ic show Cm lock Ar addr
705 The output format is as follows:
706 .Bl -tag -width "flags"
709 Possible types include
717 Flags passed to the lock initialization function.
718 For exact possibilities see manual pages of possible lock types.
720 Current state of a lock.
729 .It Ic show Cm lockchain Ar addr
730 Show all threads a particular thread at address
732 is waiting on based on non-sleepable and non-spin locks.
735 .It Ic show Cm lockedbufs
736 Show the same information as "show buf", but for every locked
741 .It Ic show Cm lockedvnods
742 List all locked vnodes in the system.
746 Prints all locks that are currently acquired.
747 This command is only available if
749 is included in the kernel.
752 .It Ic show Cm locktree
755 .It Ic show Cm malloc
758 memory allocator statistics.
759 The output format is as follows:
761 .Bl -tag -compact -offset indent -width "Requests"
763 Specifies a type of memory.
764 It is the same as a description string used while defining the
765 given memory type with
766 .Xr MALLOC_DECLARE 9 .
768 Number of memory allocations of the given type, for which
770 has not been called yet.
772 Total memory consumed by the given allocation type.
774 Number of memory allocation requests for the given
778 The same information can be gathered in userspace with
782 .It Ic show Cm map Ns Oo Li / Ns Cm f Oc Ar addr
787 modifier is specified the
788 complete map is printed.
791 .It Ic show Cm msgbuf
792 Print the system's message buffer.
793 It is the same output as in the
796 It is useful if you got a kernel panic, attached a serial cable
797 to the machine and want to get the boot messages from before the
801 Displays short info about all currently mounted file systems.
803 .It Ic show Cm mount Ar addr
804 Displays details about the given mount point.
807 .It Ic show Cm object Ns Oo Li / Ns Cm f Oc Ar addr
808 Prints the VM object at
812 option is specified the
813 complete object is printed.
817 Show statistics on VM pages.
821 Show statistics on VM page queues.
824 .It Ic show Cm pciregs
825 Print PCI bus registers.
826 The same information can be gathered in userspace by running
827 .Dq Nm pciconf Fl lv .
831 Print current processor state.
832 The output format is as follows:
834 .Bl -tag -compact -offset indent -width "spin locks held:"
836 Processor identifier.
838 Thread pointer, process identifier and the name of the process.
840 Control block pointer.
846 CPU identifier coming from APIC.
849 .It Ic spin locks held
850 Names of spin locks held.
854 .It Ic show Cm pgrpdump
855 Dump process groups present within the system.
858 .It Ic show Cm proc Op Ar addr
861 is specified, print information about the current process.
862 Otherwise, show information about the process at address
866 .It Ic show Cm procvm
867 Show process virtual memory layout.
870 .It Ic show Cm protosw Ar addr
871 Print protocol switch structure
877 .It Ic show Cm registers Ns Op Li / Ns Cm u
878 Display the register set.
881 modifier is specified, it displays user registers instead of
882 kernel registers or the currently saved one.
887 modifier depends on the machine.
888 If not supported, incorrect information will be displayed.
891 .It Ic show Cm rman Ar addr
892 Show resource manager object
896 Addresses of particular pointers can be gathered with "show allrman"
901 Show real time clock value.
902 Useful for long debugging sessions.
905 .It Ic show Cm sleepchain
906 Show all the threads a particular thread is waiting on based on
910 .It Ic show Cm sleepq
911 .It Ic show Cm sleepqueue
912 Both commands provide the same functionality.
914 .Vt struct sleepqueue
916 Sleepqueues are used within the
918 kernel to implement sleepable
919 synchronization primitives (thread holding a lock might sleep or
920 be context switched), which at the time of writing are:
928 .It Ic show Cm sockbuf Ar addr
929 .It Ic show Cm socket Ar addr
936 Output consists of all values present in structures mentioned.
937 For exact interpretation and more details, visit
942 .It Ic show Cm sysregs
943 Show system registers (e.g.,
946 Not present on some platforms.
949 .It Ic show Cm tcpcb Ar addr
950 Print TCP control block
954 For exact interpretation of output, visit
959 .It Ic show Cm thread Op Ar addr
962 is specified, show detailed information about current thread.
963 Otherwise, information about thread at
968 .It Ic show Cm threads
969 Show all threads within the system.
970 Output format is as follows:
972 .Bl -tag -compact -offset indent -width "Second column"
974 Thread identifier (TID)
976 Thread structure address
982 .It Ic show Cm tty Ar addr
983 Display the contents of a TTY structure in a readable form.
986 .It Ic show Cm turnstile Ar addr
991 Turnstiles are structures used within the
994 synchronization primitives which, while holding a specific type of lock, cannot
995 sleep or context switch to another thread.
996 Currently, those are:
1003 Show UMA allocator statistics.
1004 Output consists five columns:
1006 .Bl -tag -compact -offset indent -width "Requests"
1008 Name of the UMA zone.
1009 The same string that was passed to
1011 as a first argument.
1013 Size of a given memory object (slab).
1015 Number of slabs being currently used.
1017 Number of free slabs within the UMA zone.
1019 Number of allocations requests to the given zone.
1022 The very same information might be gathered in the userspace
1024 .Dq Nm vmstat Fl z .
1027 .It Ic show Cm unpcb Ar addr
1028 Shows UNIX domain socket private control block
1030 present at the address
1034 .It Ic show Cm vmochk
1035 Prints, whether the internal VM objects are in a map somewhere
1036 and none have zero ref counts.
1039 .It Ic show Cm vmopag
1040 This is supposed to show physical addresses consumed by a
1042 Currently, it is not possible to use this command when
1044 is compiled in the kernel.
1047 .It Ic show Cm vnode Op Ar addr
1052 For the exact interpretation of the output, look at the
1057 .It Ic show Cm vnodebufs Ar addr
1058 Shows clean/dirty buffer lists of the vnode located at
1062 .It Ic show Cm watches
1063 Displays all watchpoints.
1064 Shows watchpoints set with "watch" command.
1067 .It Ic show Cm witness
1068 Shows information about lock acquisition coming from the
1074 Toggles between remote GDB and DDB mode.
1075 In remote GDB mode, another machine is required that runs
1077 using the remote debug feature, with a connection to the serial
1078 console port on the target machine.
1079 Currently only available on the
1086 .It Ic kill Ar sig pid
1091 The signal is acted on upon returning from the debugger.
1092 This command can be used to kill a process causing resource contention
1093 in the case of a hung system.
1096 for a list of signals.
1097 Note that the arguments are reversed relative to
1100 .It Ic reboot Op Ar seconds
1101 .It Ic reset Op Ar seconds
1102 Hard reset the system.
1103 If the optional argument
1105 is given, the debugger will wait for this long, at most a week,
1109 Print a short summary of the available commands and command
1114 .It Ic capture reset
1115 .It Ic capture status
1117 supports a basic output capture facility, which can be used to retrieve the
1118 results of debugging commands from userpsace using
1121 enables output capture;
1125 will clear the capture buffer and disable capture.
1127 will report current buffer use, buffer size, and disposition of output
1130 Userspace processes may inspect and manage
1135 .Dv debug.ddb.capture.bufsize
1136 may be used to query or set the current capture buffer size.
1138 .Dv debug.ddb.capture.maxbufsize
1139 may be used to query the compile-time limit on the capture buffer size.
1141 .Dv debug.ddb.capture.bytes
1142 may be used to query the number of bytes of output currently in the capture
1145 .Dv debug.ddb.capture.data
1146 returns the contents of the buffer as a string to an appropriately privileged
1149 This facility is particularly useful in concert with the scripting and
1151 facilities, allowing scripted debugging output to be captured and
1152 committed to disk as part of a textdump for later analysis.
1153 The contents of the capture buffer may also be inspected in a kernel core dump
1161 Run, define, list, and delete scripts.
1164 section for more information on the scripting facility.
1166 .It Ic textdump dump
1168 .It Ic textdump status
1169 .It Ic textdump unset
1172 command to immediately perform a textdump.
1173 More information may be found in
1177 command may be used to force the next kernel core dump to be a textdump
1178 rather than a traditional memory dump or minidump.
1180 reports whether a textdump has been scheduled.
1182 cancels a request to perform a textdump as the next kernel core dump.
1185 The debugger accesses registers and variables as
1187 Register names are as in the
1188 .Dq Ic show Cm registers
1190 Some variables are suffixed with numbers, and may have some modifier
1191 following a colon immediately after the variable name.
1192 For example, register variables can have a
1194 modifier to indicate user register (e.g.,
1197 Built-in variables currently supported are:
1199 .Bl -tag -width ".Va tabstops" -compact
1201 Input and output radix.
1203 Addresses are printed as
1204 .Dq Ar symbol Ns Li + Ns Ar offset
1210 The width of the displayed line.
1212 The number of lines.
1213 It is used by the built-in pager.
1216 .It Va work Ns Ar xx
1219 can take values from 0 to 31.
1222 Most expression operators in C are supported except
1230 .Bl -tag -width ".No Identifiers"
1232 The name of a symbol is translated to the value of the symbol, which
1233 is the address of the corresponding object.
1237 can be used in the identifier.
1238 If supported by an object format dependent routine,
1240 .Oo Ar filename : Oc Ar func : lineno ,
1242 .Oo Ar filename : Oc Ns Ar variable ,
1244 .Oo Ar filename : Oc Ns Ar lineno
1245 can be accepted as a symbol.
1247 Radix is determined by the first two letters:
1253 decimal; otherwise, follow current radix.
1259 address of the start of the last line examined.
1264 this is only changed by
1270 last address explicitly specified.
1271 .It Li $ Ns Ar variable
1272 Translated to the value of the specified variable.
1273 It may be followed by a
1275 and modifiers as described above.
1276 .It Ar a Ns Li # Ns Ar b
1277 A binary operator which rounds up the left hand side to the next
1278 multiple of right hand side.
1281 It may be followed by a
1283 and modifiers as described above.
1287 supports a basic scripting facility to allow automating tasks or responses to
1289 Each script consists of a list of DDB commands to be executed sequentially,
1290 and is assigned a unique name.
1291 Certain script names have special meaning, and will be automatically run on
1294 events if scripts by those names have been defined.
1298 command may be used to define a script by name.
1299 Scripts consist of a series of
1301 commands separated with the
1305 .Bd -literal -offset indent
1306 script kdb.enter.panic=bt; show pcpu
1307 script lockinfo=show alllocks; show lockedvnods
1312 command lists currently defined scripts.
1316 command execute a script by name.
1318 .Bd -literal -offset indent
1324 command may be used to delete a script by name.
1326 .Bd -literal -offset indent
1327 unscript kdb.enter.panic
1330 These functions may also be performed from userspace using the
1334 Certain scripts are run automatically, if defined, for specific
1337 The follow scripts are run when various events occur:
1338 .Bl -tag -width kdb.enter.powerfail
1339 .It Dv kdb.enter.acpi
1340 The kernel debugger was entered as a result of an
1343 .It Dv kdb.enter.bootflags
1344 The kernel debugger was entered at boot as a result of the debugger boot
1346 .It Dv kdb.enter.break
1347 The kernel debugger was entered as a result of a serial or console break.
1348 .It Dv kdb.enter.cam
1349 The kernel debugger was entered as a result of a
1352 .It Dv kdb.enter.mac
1353 The kernel debugger was entered as a result of an assertion failure in the
1356 TrustedBSD MAC Framework.
1357 .It Dv kdb.enter.ndis
1358 The kernel debugger was entered as a result of an
1361 .It Dv kdb.enter.netgraph
1362 The kernel debugger was entered as a result of a
1365 .It Dv kdb.enter.panic
1368 .It Dv kdb.enter.powerfail
1369 The kernel debugger was entered as a result of a powerfail NMI on the sparc64
1371 .It Dv kdb.enter.powerpc
1372 The kernel debugger was entered as a result of an unimplemented interrupt
1373 type on the powerpc platform.
1374 .It Dv kdb.enter.sysctl
1375 The kernel debugger was entered as a result of the
1378 .It Dv kdb.enter.trapsig
1379 The kernel debugger was entered as a result of a trapsig event on the sparc64
1381 .It Dv kdb.enter.unionfs
1382 The kernel debugger was entered as a result of an assertion failure in the
1384 .It Dv kdb.enter.unknown
1385 The kernel debugger was entered, but no reason has been set.
1386 .It Dv kdb.enter.vfslock
1387 The kernel debugger was entered as a result of a VFS lock violation.
1388 .It Dv kdb.enter.watchdog
1389 The kernel debugger was entered as a result of a watchdog firing.
1390 .It Dv kdb.enter.witness
1391 The kernel debugger was entered as a result of a
1396 In the event that none of these scripts is found,
1398 will attempt to execute a default script:
1399 .Bl -tag -width kdb.enter.powerfail
1400 .It Dv kdb.enter.default
1401 The kernel debugger was entered, but a script exactly matching the reason for
1402 entering was not defined.
1403 This can be used as a catch-all to handle cases not specifically of interest;
1405 .Dv kdb.enter.witness
1406 might be defined to have special handling, and
1407 .Dv kdb.enter.default
1408 might be defined to simply panic and reboot.
1411 On machines with an ISA expansion bus, a simple NMI generation card can be
1412 constructed by connecting a push button between the A01 and B01 (CHCHK# and
1414 Momentarily shorting these two fingers together may cause the bridge chipset to
1415 generate an NMI, which causes the kernel to pass control to
1417 Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary.
1418 The NMI allows one to break into the debugger on a wedged machine to
1420 Other bus' bridge chipsets may be able to generate NMI using bus specific
1423 Header files mention in this manual page can be found below
1433 .Pa netinet/in_pcb.h
1455 debugger was developed for Mach, and ported to
1457 This manual page translated from
1460 .An Garrett Wollman .
1462 .An Robert N. M. Watson