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
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
255 .Bl -tag -width ".Tn powerpc" -compact
268 display a symbol name for the pointer stored at the address
275 command with the last specified parameters to it
276 except that the next address displayed by it is used as the start address.
282 command with the last specified parameters to it
283 except that the last start address subtracted by the size displayed by it
284 is used as the start address.
286 .It Ic print Ns Op Li / Ns Cm acdoruxz
287 .It Ic p Ns Op Li / Ns Cm acdoruxz
290 according to the modifier character (as described above for
293 .Cm a , x , z , o , d , u , r ,
296 If no modifier is specified, the last one specified to it is used.
299 can be a string, in which case it is printed as it is.
301 .Bd -literal -offset indent
302 print/x "eax = " $eax "\enecx = " $ecx "\en"
306 .Bd -literal -offset indent
312 .Ic write Ns Op Li / Ns Cm bhl
313 .Ar addr expr1 Op Ar expr2 ...
316 .Ic w Ns Op Li / Ns Cm bhl
317 .Ar addr expr1 Op Ar expr2 ...
319 Write the expressions specified after
321 on the command line at succeeding locations starting with
323 The write unit size can be specified in the modifier with a letter
329 (long word) respectively.
331 long word is assumed.
334 since there is no delimiter between expressions, strange
336 It is best to enclose each expression in parentheses.
338 .It Ic set Li $ Ns Ar variable Oo Li = Oc Ar expr
339 Set the named variable or register with the value of
341 Valid variable names are described below.
343 .It Ic break Ns Op Li / Ns Cm u
344 .It Ic b Ns Op Li / Ns Cm u
349 is supplied, continues
351 \- 1 times before stopping at the
353 If the break point is set, a break point number is
356 This number can be used in deleting the break point
357 or adding conditions to it.
361 modifier is specified, this command sets a break point in user
365 option, the address is considered to be in the kernel
366 space, and a wrong space address is rejected with an error message.
367 This modifier can be used only if it is supported by machine dependent
371 If a user text is shadowed by a normal user space debugger,
372 user space break points may not work correctly.
374 point at the low-level code paths may also cause strange behavior.
376 .It Ic delete Ar addr
378 .It Ic delete Li # Ns Ar number
379 .It Ic d Li # Ns Ar number
380 Delete the break point.
381 The target break point can be specified by a
382 break point number with
386 specified in the original
390 .It Ic watch Ar addr Ns Li , Ns Ar size
391 Set a watchpoint for a region.
392 Execution stops when an attempt to modify the region occurs.
395 argument defaults to 4.
396 If you specify a wrong space address, the request is rejected
397 with an error message.
400 Attempts to watch wired kernel memory
401 may cause unrecoverable error in some systems such as i386.
402 Watchpoints on user addresses work best.
404 .It Ic hwatch Ar addr Ns Li , Ns Ar size
405 Set a hardware watchpoint for a region if supported by the
407 Execution stops when an attempt to modify the region occurs.
410 argument defaults to 4.
413 The hardware debug facilities do not have a concept of separate
414 address spaces like the watch command does.
417 for setting watchpoints on kernel address locations only, and avoid
418 its use on user mode address spaces.
420 .It Ic dhwatch Ar addr Ns Li , Ns Ar size
421 Delete specified hardware watchpoint.
423 .It Ic step Ns Op Li / Ns Cm p
424 .It Ic s Ns Op Li / Ns Cm p
427 times (the comma is a mandatory part of the syntax).
430 modifier is specified, print each instruction at each step.
431 Otherwise, only print the last instruction.
434 depending on machine type, it may not be possible to
435 single-step through some low-level code paths or user space code.
436 On machines with software-emulated single-stepping (e.g., pmax),
437 stepping through code executed by interrupt handlers will probably
440 .It Ic continue Ns Op Li / Ns Cm c
441 .It Ic c Ns Op Li / Ns Cm c
442 Continue execution until a breakpoint or watchpoint.
445 modifier is specified, count instructions while executing.
446 Some machines (e.g., pmax) also count loads and stores.
449 when counting, the debugger is really silently single-stepping.
450 This means that single-stepping on low-level code may cause strange
453 .It Ic until Ns Op Li / Ns Cm p
454 Stop at the next call or return instruction.
457 modifier is specified, print the call nesting depth and the
458 cumulative instruction count at each call or return.
460 only print when the matching return is hit.
462 .It Ic next Ns Op Li / Ns Cm p
463 .It Ic match Ns Op Li / Ns Cm p
464 Stop at the matching return instruction.
467 modifier is specified, print the call nesting depth and the
468 cumulative instruction count at each call or return.
469 Otherwise, only print when the matching return is hit.
472 .Ic trace Ns Op Li / Ns Cm u
477 .Ic t Ns Op Li / Ns Cm u
482 .Ic where Ns Op Li / Ns Cm u
487 .Ic bt Ns Op Li / Ns Cm u
494 option traces user space; if omitted,
498 The optional argument
500 is the number of frames to be traced.
503 is omitted, all frames are printed.
506 User space stack trace is valid
507 only if the machine dependent code supports it.
510 .Ic search Ns Op Li / Ns Cm bhl
518 This command might fail in interesting
519 ways if it does not find the searched-for value.
522 does not always recover from touching bad memory.
525 argument limits the search.
532 Prints the thread address for a thread kernel-mode stack of which contains the
534 If the thread is not found, search the thread stack cache and prints the
535 cached stack address.
536 Otherwise, prints nothing.
538 .It Ic show Cm all procs Ns Op Li / Ns Cm m
539 .It Ic ps Ns Op Li / Ns Cm m
540 Display all process information.
541 The process information may not be shown if it is not
542 supported in the machine, or the bottom of the stack of the
543 target process is not in the main memory at that time.
546 modifier will alter the display to show VM map
547 addresses for the process and not show other information.
550 .It Ic show Cm all trace
553 Show a stack trace for every thread in the system.
555 .It Ic show Cm all ttys
556 Show all TTY's within the system.
559 but also includes the address of the TTY structure.
562 .It Ic show Cm allchains
563 Show the same information like "show lockchain" does, but
564 for every thread in the system.
567 .It Ic show Cm alllocks
568 Show all locks that are currently held.
569 This command is only available if
571 is included in the kernel.
574 .It Ic show Cm allpcpu
575 The same as "show pcpu", but for every CPU present in the system.
578 .It Ic show Cm allrman
579 Show information related with resource management, including
580 interrupt request lines, DMA request lines, I/O ports, I/O memory
581 addresses, and Resource IDs.
585 Dump data about APIC IDT vector mappings.
588 .It Ic show Cm breaks
589 Show breakpoints set with the "break" command.
592 .It Ic show Cm bio Ar addr
593 Show information about the bio structure
601 for more details on the exact meaning of the structure fields.
604 .It Ic show Cm buffer Ar addr
605 Show information about the buf structure
611 header file for more details on the exact meaning of the structure fields.
614 .It Ic show Cm cbstat
615 Show brief information about the TTY subsystem.
619 Without argument, show the list of all created cdev's, consisting of devfs
620 node name and struct cdev address.
621 When address of cdev is supplied, show some internal devfs state of the cdev.
624 .It Ic show Cm conifhk
625 Lists hooks currently waiting for completion in
626 run_interrupt_driven_config_hooks().
629 .It Ic show Cm cpusets
630 Print numbered root and assigned CPU affinity sets.
636 .It Ic show Cm cyrixreg
637 Show registers specific to the Cyrix processor.
640 .It Ic show Cm domain Ar addr
641 Print protocol domain structure
647 header file for more details on the exact meaning of the structure fields.
650 .It Ic show Cm ffs Op Ar addr
651 Show brief information about ffs mount at the address
653 if argument is given.
654 Otherwise, provides the summary about each ffs mount.
657 .It Ic show Cm file Ar addr
658 Show information about the file structure
665 Show information about every file structure in the system.
668 .It Ic show Cm freepages
669 Show the number of physical pages in each of the free lists.
672 .It Ic show Cm geom Op Ar addr
675 argument is not given, displays the entire GEOM topology.
678 is given, displays details about the given GEOM object (class, geom,
679 provider or consumer).
684 The first column specifies the IDT vector.
685 The second one is the name of the interrupt/trap handler.
686 Those functions are machine dependent.
689 .It Ic show Cm inodedeps Op Ar addr
690 Show brief information about each inodedep structure.
693 is given, only inodedeps belonging to the fs located at the
694 supplied address are shown.
697 .It Ic show Cm inpcb Ar addr
698 Show information on IP Control Block
705 Dump information about interrupt handlers.
708 .It Ic show Cm intrcnt
709 Dump the interrupt statistics.
713 Show interrupt lines and their respective kernel threads.
722 shows, also list kernel internal details.
726 Show information from the local APIC registers for this CPU.
729 .It Ic show Cm lock Ar addr
731 The output format is as follows:
732 .Bl -tag -width "flags"
735 Possible types include
743 Flags passed to the lock initialization function.
744 For exact possibilities see manual pages of possible lock types.
746 Current state of a lock.
755 .It Ic show Cm lockchain Ar addr
756 Show all threads a particular thread at address
758 is waiting on based on non-sleepable and non-spin locks.
761 .It Ic show Cm lockedbufs
762 Show the same information as "show buf", but for every locked
767 .It Ic show Cm lockedvnods
768 List all locked vnodes in the system.
772 Prints all locks that are currently acquired.
773 This command is only available if
775 is included in the kernel.
778 .It Ic show Cm locktree
781 .It Ic show Cm malloc
784 memory allocator statistics.
785 The output format is as follows:
787 .Bl -tag -compact -offset indent -width "Requests"
789 Specifies a type of memory.
790 It is the same as a description string used while defining the
791 given memory type with
792 .Xr MALLOC_DECLARE 9 .
794 Number of memory allocations of the given type, for which
796 has not been called yet.
798 Total memory consumed by the given allocation type.
800 Number of memory allocation requests for the given
804 The same information can be gathered in userspace with
808 .It Ic show Cm map Ns Oo Li / Ns Cm f Oc Ar addr
813 modifier is specified the
814 complete map is printed.
817 .It Ic show Cm msgbuf
818 Print the system's message buffer.
819 It is the same output as in the
822 It is useful if you got a kernel panic, attached a serial cable
823 to the machine and want to get the boot messages from before the
827 Displays short info about all currently mounted file systems.
829 .It Ic show Cm mount Ar addr
830 Displays details about the given mount point.
833 .It Ic show Cm object Ns Oo Li / Ns Cm f Oc Ar addr
834 Prints the VM object at
838 option is specified the
839 complete object is printed.
843 Show statistics on VM pages.
847 Show statistics on VM page queues.
850 .It Ic show Cm pciregs
851 Print PCI bus registers.
852 The same information can be gathered in userspace by running
853 .Dq Nm pciconf Fl lv .
857 Print current processor state.
858 The output format is as follows:
860 .Bl -tag -compact -offset indent -width "spin locks held:"
862 Processor identifier.
864 Thread pointer, process identifier and the name of the process.
866 Control block pointer.
872 CPU identifier coming from APIC.
875 .It Ic spin locks held
876 Names of spin locks held.
880 .It Ic show Cm pgrpdump
881 Dump process groups present within the system.
884 .It Ic show Cm proc Op Ar addr
887 is specified, print information about the current process.
888 Otherwise, show information about the process at address
892 .It Ic show Cm procvm
893 Show process virtual memory layout.
896 .It Ic show Cm protosw Ar addr
897 Print protocol switch structure
903 .It Ic show Cm registers Ns Op Li / Ns Cm u
904 Display the register set.
907 modifier is specified, it displays user registers instead of
908 kernel registers or the currently saved one.
913 modifier depends on the machine.
914 If not supported, incorrect information will be displayed.
917 .It Ic show Cm rman Ar addr
918 Show resource manager object
922 Addresses of particular pointers can be gathered with "show allrman"
927 Show real time clock value.
928 Useful for long debugging sessions.
931 .It Ic show Cm sleepchain
932 Show all the threads a particular thread is waiting on based on
936 .It Ic show Cm sleepq
937 .It Ic show Cm sleepqueue
938 Both commands provide the same functionality.
940 .Vt struct sleepqueue
942 Sleepqueues are used within the
944 kernel to implement sleepable
945 synchronization primitives (thread holding a lock might sleep or
946 be context switched), which at the time of writing are:
954 .It Ic show Cm sockbuf Ar addr
955 .It Ic show Cm socket Ar addr
962 Output consists of all values present in structures mentioned.
963 For exact interpretation and more details, visit
968 .It Ic show Cm sysregs
969 Show system registers (e.g.,
972 Not present on some platforms.
975 .It Ic show Cm tcpcb Ar addr
976 Print TCP control block
980 For exact interpretation of output, visit
985 .It Ic show Cm thread Op Ar addr
988 is specified, show detailed information about current thread.
989 Otherwise, information about thread at
994 .It Ic show Cm threads
995 Show all threads within the system.
996 Output format is as follows:
998 .Bl -tag -compact -offset indent -width "Second column"
1000 Thread identifier (TID)
1001 .It Ic Second column
1002 Thread structure address
1008 .It Ic show Cm tty Ar addr
1009 Display the contents of a TTY structure in a readable form.
1012 .It Ic show Cm turnstile Ar addr
1014 .Vt struct turnstile
1015 structure at address
1017 Turnstiles are structures used within the
1020 synchronization primitives which, while holding a specific type of lock, cannot
1021 sleep or context switch to another thread.
1022 Currently, those are:
1029 Show UMA allocator statistics.
1030 Output consists five columns:
1032 .Bl -tag -compact -offset indent -width "Requests"
1034 Name of the UMA zone.
1035 The same string that was passed to
1037 as a first argument.
1039 Size of a given memory object (slab).
1041 Number of slabs being currently used.
1043 Number of free slabs within the UMA zone.
1045 Number of allocations requests to the given zone.
1048 The very same information might be gathered in the userspace
1050 .Dq Nm vmstat Fl z .
1053 .It Ic show Cm unpcb Ar addr
1054 Shows UNIX domain socket private control block
1056 present at the address
1060 .It Ic show Cm vmochk
1061 Prints, whether the internal VM objects are in a map somewhere
1062 and none have zero ref counts.
1065 .It Ic show Cm vmopag
1066 This is supposed to show physical addresses consumed by a
1068 Currently, it is not possible to use this command when
1070 is compiled in the kernel.
1073 .It Ic show Cm vnode Op Ar addr
1078 For the exact interpretation of the output, look at the
1083 .It Ic show Cm vnodebufs Ar addr
1084 Shows clean/dirty buffer lists of the vnode located at
1088 .It Ic show Cm watches
1089 Displays all watchpoints.
1090 Shows watchpoints set with "watch" command.
1093 .It Ic show Cm witness
1094 Shows information about lock acquisition coming from the
1100 Toggles between remote GDB and DDB mode.
1101 In remote GDB mode, another machine is required that runs
1103 using the remote debug feature, with a connection to the serial
1104 console port on the target machine.
1105 Currently only available on the
1112 .It Ic kill Ar sig pid
1117 The signal is acted on upon returning from the debugger.
1118 This command can be used to kill a process causing resource contention
1119 in the case of a hung system.
1122 for a list of signals.
1123 Note that the arguments are reversed relative to
1126 .It Ic reboot Op Ar seconds
1127 .It Ic reset Op Ar seconds
1128 Hard reset the system.
1129 If the optional argument
1131 is given, the debugger will wait for this long, at most a week,
1135 Print a short summary of the available commands and command
1140 .It Ic capture reset
1141 .It Ic capture status
1143 supports a basic output capture facility, which can be used to retrieve the
1144 results of debugging commands from userpsace using
1147 enables output capture;
1151 will clear the capture buffer and disable capture.
1153 will report current buffer use, buffer size, and disposition of output
1156 Userspace processes may inspect and manage
1161 .Dv debug.ddb.capture.bufsize
1162 may be used to query or set the current capture buffer size.
1164 .Dv debug.ddb.capture.maxbufsize
1165 may be used to query the compile-time limit on the capture buffer size.
1167 .Dv debug.ddb.capture.bytes
1168 may be used to query the number of bytes of output currently in the capture
1171 .Dv debug.ddb.capture.data
1172 returns the contents of the buffer as a string to an appropriately privileged
1175 This facility is particularly useful in concert with the scripting and
1177 facilities, allowing scripted debugging output to be captured and
1178 committed to disk as part of a textdump for later analysis.
1179 The contents of the capture buffer may also be inspected in a kernel core dump
1187 Run, define, list, and delete scripts.
1190 section for more information on the scripting facility.
1192 .It Ic textdump dump
1194 .It Ic textdump status
1195 .It Ic textdump unset
1198 command to immediately perform a textdump.
1199 More information may be found in
1203 command may be used to force the next kernel core dump to be a textdump
1204 rather than a traditional memory dump or minidump.
1206 reports whether a textdump has been scheduled.
1208 cancels a request to perform a textdump as the next kernel core dump.
1211 The debugger accesses registers and variables as
1213 Register names are as in the
1214 .Dq Ic show Cm registers
1216 Some variables are suffixed with numbers, and may have some modifier
1217 following a colon immediately after the variable name.
1218 For example, register variables can have a
1220 modifier to indicate user register (e.g.,
1223 Built-in variables currently supported are:
1225 .Bl -tag -width ".Va tabstops" -compact
1227 Input and output radix.
1229 Addresses are printed as
1230 .Dq Ar symbol Ns Li + Ns Ar offset
1236 The width of the displayed line.
1238 The number of lines.
1239 It is used by the built-in pager.
1242 .It Va work Ns Ar xx
1245 can take values from 0 to 31.
1248 Most expression operators in C are supported except
1256 .Bl -tag -width ".No Identifiers"
1258 The name of a symbol is translated to the value of the symbol, which
1259 is the address of the corresponding object.
1263 can be used in the identifier.
1264 If supported by an object format dependent routine,
1266 .Oo Ar filename : Oc Ar func : lineno ,
1268 .Oo Ar filename : Oc Ns Ar variable ,
1270 .Oo Ar filename : Oc Ns Ar lineno
1271 can be accepted as a symbol.
1273 Radix is determined by the first two letters:
1279 decimal; otherwise, follow current radix.
1285 address of the start of the last line examined.
1290 this is only changed by
1296 last address explicitly specified.
1297 .It Li $ Ns Ar variable
1298 Translated to the value of the specified variable.
1299 It may be followed by a
1301 and modifiers as described above.
1302 .It Ar a Ns Li # Ns Ar b
1303 A binary operator which rounds up the left hand side to the next
1304 multiple of right hand side.
1307 It may be followed by a
1309 and modifiers as described above.
1313 supports a basic scripting facility to allow automating tasks or responses to
1315 Each script consists of a list of DDB commands to be executed sequentially,
1316 and is assigned a unique name.
1317 Certain script names have special meaning, and will be automatically run on
1320 events if scripts by those names have been defined.
1324 command may be used to define a script by name.
1325 Scripts consist of a series of
1327 commands separated with the
1331 .Bd -literal -offset indent
1332 script kdb.enter.panic=bt; show pcpu
1333 script lockinfo=show alllocks; show lockedvnods
1338 command lists currently defined scripts.
1342 command execute a script by name.
1344 .Bd -literal -offset indent
1350 command may be used to delete a script by name.
1352 .Bd -literal -offset indent
1353 unscript kdb.enter.panic
1356 These functions may also be performed from userspace using the
1360 Certain scripts are run automatically, if defined, for specific
1363 The follow scripts are run when various events occur:
1364 .Bl -tag -width kdb.enter.powerfail
1365 .It Dv kdb.enter.acpi
1366 The kernel debugger was entered as a result of an
1369 .It Dv kdb.enter.bootflags
1370 The kernel debugger was entered at boot as a result of the debugger boot
1372 .It Dv kdb.enter.break
1373 The kernel debugger was entered as a result of a serial or console break.
1374 .It Dv kdb.enter.cam
1375 The kernel debugger was entered as a result of a
1378 .It Dv kdb.enter.mac
1379 The kernel debugger was entered as a result of an assertion failure in the
1382 TrustedBSD MAC Framework.
1383 .It Dv kdb.enter.ndis
1384 The kernel debugger was entered as a result of an
1387 .It Dv kdb.enter.netgraph
1388 The kernel debugger was entered as a result of a
1391 .It Dv kdb.enter.panic
1394 .It Dv kdb.enter.powerfail
1395 The kernel debugger was entered as a result of a powerfail NMI on the sparc64
1397 .It Dv kdb.enter.powerpc
1398 The kernel debugger was entered as a result of an unimplemented interrupt
1399 type on the powerpc platform.
1400 .It Dv kdb.enter.sysctl
1401 The kernel debugger was entered as a result of the
1404 .It Dv kdb.enter.trapsig
1405 The kernel debugger was entered as a result of a trapsig event on the sparc64
1407 .It Dv kdb.enter.unionfs
1408 The kernel debugger was entered as a result of an assertion failure in the
1410 .It Dv kdb.enter.unknown
1411 The kernel debugger was entered, but no reason has been set.
1412 .It Dv kdb.enter.vfslock
1413 The kernel debugger was entered as a result of a VFS lock violation.
1414 .It Dv kdb.enter.watchdog
1415 The kernel debugger was entered as a result of a watchdog firing.
1416 .It Dv kdb.enter.witness
1417 The kernel debugger was entered as a result of a
1422 In the event that none of these scripts is found,
1424 will attempt to execute a default script:
1425 .Bl -tag -width kdb.enter.powerfail
1426 .It Dv kdb.enter.default
1427 The kernel debugger was entered, but a script exactly matching the reason for
1428 entering was not defined.
1429 This can be used as a catch-all to handle cases not specifically of interest;
1431 .Dv kdb.enter.witness
1432 might be defined to have special handling, and
1433 .Dv kdb.enter.default
1434 might be defined to simply panic and reboot.
1437 On machines with an ISA expansion bus, a simple NMI generation card can be
1438 constructed by connecting a push button between the A01 and B01 (CHCHK# and
1440 Momentarily shorting these two fingers together may cause the bridge chipset to
1441 generate an NMI, which causes the kernel to pass control to
1443 Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary.
1444 The NMI allows one to break into the debugger on a wedged machine to
1446 Other bus' bridge chipsets may be able to generate NMI using bus specific
1449 Header files mention in this manual page can be found below
1459 .Pa netinet/in_pcb.h
1481 debugger was developed for Mach, and ported to
1483 This manual page translated from
1486 .An Garrett Wollman .
1488 .An Robert N. M. Watson