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 print the location being displayed
225 print the location with a line number if possible
227 display in unsigned hex
229 display in signed hex
231 display in unsigned octal
233 display in signed decimal
235 display in unsigned decimal
237 display in current radix, signed
239 display low 8 bits as a character.
240 Non-printing characters are displayed as an octal escape code (e.g.,
243 display the null-terminated string at the location.
244 Non-printing characters are displayed as octal escapes.
246 display in unsigned hex with character dump at the end of each line.
247 The location is also displayed in hex at the beginning of each line.
249 display as an instruction
251 display as an instruction with possible alternate formats depending on the
253 .Bl -tag -width ".Tn powerpc" -compact
266 display a symbol name for the pointer stored at the address
273 command with the last specified parameters to it
274 except that the next address displayed by it is used as the start address.
280 command with the last specified parameters to it
281 except that the last start address subtracted by the size displayed by it
282 is used as the start address.
284 .It Ic print Ns Op Li / Ns Cm acdoruxz
285 .It Ic p Ns Op Li / Ns Cm acdoruxz
288 according to the modifier character (as described above for
291 .Cm a , x , z , o , d , u , r ,
294 If no modifier is specified, the last one specified to it is used.
297 can be a string, in which case it is printed as it is.
299 .Bd -literal -offset indent
300 print/x "eax = " $eax "\enecx = " $ecx "\en"
304 .Bd -literal -offset indent
310 .Ic write Ns Op Li / Ns Cm bhl
311 .Ar addr expr1 Op Ar expr2 ...
314 .Ic w Ns Op Li / Ns Cm bhl
315 .Ar addr expr1 Op Ar expr2 ...
317 Write the expressions specified after
319 on the command line at succeeding locations starting with
321 The write unit size can be specified in the modifier with a letter
327 (long word) respectively.
329 long word is assumed.
332 since there is no delimiter between expressions, strange
334 It is best to enclose each expression in parentheses.
336 .It Ic set Li $ Ns Ar variable Oo Li = Oc Ar expr
337 Set the named variable or register with the value of
339 Valid variable names are described below.
341 .It Ic break Ns Op Li / Ns Cm u
342 .It Ic b Ns Op Li / Ns Cm u
347 is supplied, continues
349 \- 1 times before stopping at the
351 If the break point is set, a break point number is
354 This number can be used in deleting the break point
355 or adding conditions to it.
359 modifier is specified, this command sets a break point in user
363 option, the address is considered to be in the kernel
364 space, and a wrong space address is rejected with an error message.
365 This modifier can be used only if it is supported by machine dependent
369 If a user text is shadowed by a normal user space debugger,
370 user space break points may not work correctly.
372 point at the low-level code paths may also cause strange behavior.
374 .It Ic delete Ar addr
376 .It Ic delete Li # Ns Ar number
377 .It Ic d Li # Ns Ar number
378 Delete the break point.
379 The target break point can be specified by a
380 break point number with
384 specified in the original
388 .It Ic watch Ar addr Ns Li , Ns Ar size
389 Set a watchpoint for a region.
390 Execution stops when an attempt to modify the region occurs.
393 argument defaults to 4.
394 If you specify a wrong space address, the request is rejected
395 with an error message.
398 Attempts to watch wired kernel memory
399 may cause unrecoverable error in some systems such as i386.
400 Watchpoints on user addresses work best.
402 .It Ic hwatch Ar addr Ns Li , Ns Ar size
403 Set a hardware watchpoint for a region if supported by the
405 Execution stops when an attempt to modify the region occurs.
408 argument defaults to 4.
411 The hardware debug facilities do not have a concept of separate
412 address spaces like the watch command does.
415 for setting watchpoints on kernel address locations only, and avoid
416 its use on user mode address spaces.
418 .It Ic dhwatch Ar addr Ns Li , Ns Ar size
419 Delete specified hardware watchpoint.
421 .It Ic step Ns Op Li / Ns Cm p
422 .It Ic s Ns Op Li / Ns Cm p
425 times (the comma is a mandatory part of the syntax).
428 modifier is specified, print each instruction at each step.
429 Otherwise, only print the last instruction.
432 depending on machine type, it may not be possible to
433 single-step through some low-level code paths or user space code.
434 On machines with software-emulated single-stepping (e.g., pmax),
435 stepping through code executed by interrupt handlers will probably
438 .It Ic continue Ns Op Li / Ns Cm c
439 .It Ic c Ns Op Li / Ns Cm c
440 Continue execution until a breakpoint or watchpoint.
443 modifier is specified, count instructions while executing.
444 Some machines (e.g., pmax) also count loads and stores.
447 when counting, the debugger is really silently single-stepping.
448 This means that single-stepping on low-level code may cause strange
451 .It Ic until Ns Op Li / Ns Cm p
452 Stop at the next call or return instruction.
455 modifier is specified, print the call nesting depth and the
456 cumulative instruction count at each call or return.
458 only print when the matching return is hit.
460 .It Ic next Ns Op Li / Ns Cm p
461 .It Ic match Ns Op Li / Ns Cm p
462 Stop at the matching return instruction.
465 modifier is specified, print the call nesting depth and the
466 cumulative instruction count at each call or return.
467 Otherwise, only print when the matching return is hit.
470 .Ic trace Ns Op Li / Ns Cm u
475 .Ic t Ns Op Li / Ns Cm u
480 .Ic where Ns Op Li / Ns Cm u
485 .Ic bt Ns Op Li / Ns Cm u
492 option traces user space; if omitted,
496 The optional argument
498 is the number of frames to be traced.
501 is omitted, all frames are printed.
504 User space stack trace is valid
505 only if the machine dependent code supports it.
508 .Ic search Ns Op Li / Ns Cm bhl
516 This command might fail in interesting
517 ways if it does not find the searched-for value.
520 does not always recover from touching bad memory.
523 argument limits the search.
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.
808 .It Ic show Cm object Ns Oo Li / Ns Cm f Oc Ar addr
809 Prints the VM object at
813 option is specified the
814 complete object is printed.
818 Show statistics on VM pages.
822 Show statistics on VM page queues.
825 .It Ic show Cm pciregs
826 Print PCI bus registers.
827 The same information can be gathered in userspace by running
828 .Dq Nm pciconf Fl lv .
832 Print current processor state.
833 The output format is as follows:
835 .Bl -tag -compact -offset indent -width "spin locks held:"
837 Processor identifier.
839 Thread pointer, process identifier and the name of the process.
841 Control block pointer.
847 CPU identifier coming from APIC.
850 .It Ic spin locks held
851 Names of spin locks held.
855 .It Ic show Cm pgrpdump
856 Dump process groups present within the system.
859 .It Ic show Cm proc Op Ar addr
862 is specified, print information about the current process.
863 Otherwise, show information about the process at address
867 .It Ic show Cm procvm
868 Show process virtual memory layout.
871 .It Ic show Cm protosw Ar addr
872 Print protocol switch structure
878 .It Ic show Cm registers Ns Op Li / Ns Cm u
879 Display the register set.
882 modifier is specified, it displays user registers instead of
883 kernel registers or the currently saved one.
888 modifier depends on the machine.
889 If not supported, incorrect information will be displayed.
892 .It Ic show Cm rman Ar addr
893 Show resource manager object
897 Addresses of particular pointers can be gathered with "show allrman"
902 Show real time clock value.
903 Useful for long debugging sessions.
906 .It Ic show Cm sleepchain
907 Show all the threads a particular thread is waiting on based on
911 .It Ic show Cm sleepq
912 .It Ic show Cm sleepqueue
913 Both commands provide the same functionality.
915 .Vt struct sleepqueue
917 Sleepqueues are used within the
919 kernel to implement sleepable
920 synchronization primitives (thread holding a lock might sleep or
921 be context switched), which at the time of writing are:
929 .It Ic show Cm sockbuf Ar addr
930 .It Ic show Cm socket Ar addr
937 Output consists of all values present in structures mentioned.
938 For exact interpretation and more details, visit
943 .It Ic show Cm sysregs
944 Show system registers (e.g.,
947 Not present on some platforms.
950 .It Ic show Cm tcpcb Ar addr
951 Print TCP control block
955 For exact interpretation of output, visit
960 .It Ic show Cm thread Op Ar addr
963 is specified, show detailed information about current thread.
964 Otherwise, information about thread at
969 .It Ic show Cm threads
970 Show all threads within the system.
971 Output format is as follows:
973 .Bl -tag -width "PPID" -compact -offset indent -width "Second column"
975 Thread identifier (TID)
977 Thread structure address
983 .It Ic show Cm tty Ar addr
984 Display the contents of a TTY structure in a readable form.
987 .It Ic show Cm turnstile Ar addr
992 Turnstiles are structures used within the
995 synchronization primitives which, while holding a specific type of lock, cannot
996 sleep or context switch to another thread.
997 Currently, those are:
1004 Show UMA allocator statistics.
1005 Output consists five columns:
1007 .Bl -tag -compact -offset indent -width "Requests"
1009 Name of the UMA zone.
1010 The same string that was passed to
1012 as a first argument.
1014 Size of a given memory object (slab).
1016 Number of slabs being currently used.
1018 Number of free slabs within the UMA zone.
1020 Number of allocations requests to the given zone.
1023 The very same information might be gathered in the userspace
1025 .Dq Nm vmstat Fl z .
1028 .It Ic show Cm unpcb Ar addr
1029 Shows UNIX domain socket private control block
1031 present at the address
1035 .It Ic show Cm vmochk
1036 Prints, whether the internal VM objects are in a map somewhere
1037 and none have zero ref counts.
1040 .It Ic show Cm vmopag
1041 This is supposed to show physical addresses consumed by a
1043 Currently, it is not possible to use this command when
1045 is compiled in the kernel.
1048 .It Ic show Cm vnode Op Ar addr
1053 For the exact interpretation of the output, look at the
1058 .It Ic show Cm vnodebufs Ar addr
1059 Shows clean/dirty buffer lists of the vnode located at
1063 .It Ic show Cm watches
1064 Displays all watchpoints.
1065 Shows watchpoints set with "watch" command.
1068 .It Ic show Cm witness
1069 Shows information about lock acquisition coming from the
1075 Toggles between remote GDB and DDB mode.
1076 In remote GDB mode, another machine is required that runs
1078 using the remote debug feature, with a connection to the serial
1079 console port on the target machine.
1080 Currently only available on the
1087 .It Ic kill Ar sig pid
1092 The signal is acted on upon returning from the debugger.
1093 This command can be used to kill a process causing resource contention
1094 in the case of a hung system.
1097 for a list of signals.
1098 Note that the arguments are reversed relative to
1101 .It Ic reboot Op Ar seconds
1102 .It Ic reset Op Ar seconds
1103 Hard reset the system.
1104 If the optional argument
1106 is given, the debugger will wait for this long, at most a week,
1110 Print a short summary of the available commands and command
1115 .It Ic capture reset
1116 .It Ic capture status
1118 supports a basic output capture facility, which can be used to retrieve the
1119 results of debugging commands from userpsace using
1122 enables output capture;
1126 will clear the capture buffer and disable capture.
1128 will report current buffer use, buffer size, and disposition of output
1131 Userspace processes may inspect and manage
1136 .Dv debug.ddb.capture.bufsize
1137 may be used to query or set the current capture buffer size.
1139 .Dv debug.ddb.capture.maxbufsize
1140 may be used to query the compile-time limit on the capture buffer size.
1142 .Dv debug.ddb.capture.bytes
1143 may be used to query the number of bytes of output currently in the capture
1146 .Dv debug.ddb.capture.data
1147 returns the contents of the buffer as a string to an appropriately privileged
1150 This facility is particularly useful in concert with the scripting and
1152 facilities, allowing scripted debugging output to be captured and
1153 committed to disk as part of a textdump for later analysis.
1154 The contents of the capture buffer may also be inspected in a kernel core dump
1162 Run, define, list, and delete scripts.
1165 section for more information on the scripting facility.
1168 .It Ic textdump status
1169 .It Ic textdump unset
1172 command may be used to force the next kernel core dump to be a textdump
1173 rather than a traditional memory dump or minidump.
1175 reports whether a textdump has been scheduled.
1177 cancels a request to perform a textdump as the next kernel core dump.
1178 More information may be found in
1182 The debugger accesses registers and variables as
1184 Register names are as in the
1185 .Dq Ic show Cm registers
1187 Some variables are suffixed with numbers, and may have some modifier
1188 following a colon immediately after the variable name.
1189 For example, register variables can have a
1191 modifier to indicate user register (e.g.,
1194 Built-in variables currently supported are:
1196 .Bl -tag -width ".Va tabstops" -compact
1198 Input and output radix.
1200 Addresses are printed as
1201 .Dq Ar symbol Ns Li + Ns Ar offset
1207 The width of the displayed line.
1209 The number of lines.
1210 It is used by the built-in pager.
1213 .It Va work Ns Ar xx
1216 can take values from 0 to 31.
1219 Most expression operators in C are supported except
1227 .Bl -tag -width ".No Identifiers"
1229 The name of a symbol is translated to the value of the symbol, which
1230 is the address of the corresponding object.
1234 can be used in the identifier.
1235 If supported by an object format dependent routine,
1237 .Oo Ar filename : Oc Ar func : lineno ,
1239 .Oo Ar filename : Oc Ns Ar variable ,
1241 .Oo Ar filename : Oc Ns Ar lineno
1242 can be accepted as a symbol.
1244 Radix is determined by the first two letters:
1250 decimal; otherwise, follow current radix.
1256 address of the start of the last line examined.
1261 this is only changed by
1267 last address explicitly specified.
1268 .It Li $ Ns Ar variable
1269 Translated to the value of the specified variable.
1270 It may be followed by a
1272 and modifiers as described above.
1273 .It Ar a Ns Li # Ns Ar b
1274 A binary operator which rounds up the left hand side to the next
1275 multiple of right hand side.
1278 It may be followed by a
1280 and modifiers as described above.
1284 supports a basic scripting facility to allow automating tasks or responses to
1286 Each script consists of a list of DDB commands to be executed sequentially,
1287 and is assigned a unique name.
1288 Certain script names have special meaning, and will be automatically run on
1291 events if scripts by those names have been defined.
1295 command may be used to define a script by name.
1296 Scripts consist of a series of
1298 commands separated with the
1302 .Bd -literal -offset indent
1303 script kdb.enter.panic=bt; show pcpu
1304 script lockinfo=show alllocks; show lockedvnods
1309 command lists currently defined scripts.
1313 command execute a script by name.
1315 .Bd -literal -offset indent
1321 command may be used to delete a script by name.
1323 .Bd -literal -offset indent
1324 unscript kdb.enter.panic
1327 These functions may also be performed from userspace using the
1331 Certain scripts are run automatically, if defined, for specific
1334 The follow scripts are run when various events occur:
1335 .Bl -tag -width kdb.enter.powerfail
1336 .It Dv kdb.enter.acpi
1337 The kernel debugger was entered as a result of an
1340 .It Dv kdb.enter.bootflags
1341 The kernel debugger was entered at boot as a result of the debugger boot
1343 .It Dv kdb.enter.break
1344 The kernel debugger was entered as a result of a serial or console break.
1345 .It Dv kdb.enter.cam
1346 The kernel debugger was entered as a result of a
1349 .It Dv kdb.enter.mac
1350 The kernel debugger was entered as a result of an assertion failure in the
1353 TrustedBSD MAC Framework.
1354 .It Dv kdb.enter.ndis
1355 The kernel debugger was entered as a result of an
1358 .It Dv kdb.enter.netgraph
1359 The kernel debugger was entered as a result of a
1362 .It Dv kdb.enter.panic
1365 .It Dv kdb.enter.powerfail
1366 The kernel debugger was entered as a result of a powerfail NMI on the sparc64
1368 .It Dv kdb.enter.powerpc
1369 The kernel debugger was entered as a result of an unimplemented interrupt
1370 type on the powerpc platform.
1371 .It Dv kdb.enter.sysctl
1372 The kernel debugger was entered as a result of the
1375 .It Dv kdb.enter.trapsig
1376 The kernel debugger was entered as a result of a trapsig event on the sparc64
1378 .It Dv kdb.enter.unionfs
1379 The kernel debugger was entered as a result of an assertion failure in the
1381 .It Dv kdb.enter.unknown
1382 The kernel debugger was entered, but no reason has been set.
1383 .It Dv kdb.enter.vfslock
1384 The kernel debugger was entered as a result of a VFS lock violation.
1385 .It Dv kdb.enter.watchdog
1386 The kernel debugger was entered as a result of a watchdog firing.
1387 .It Dv kdb.enter.witness
1388 The kernel debugger was entered as a result of a
1393 In the event that none of these scripts is found,
1395 will attempt to execute a default script:
1396 .Bl -tag -width kdb.enter.powerfail
1397 .It Dv kdb.enter.default
1398 The kernel debugger was entered, but a script exactly matching the reason for
1399 entering was not defined.
1400 This can be used as a catch-all to handle cases not specifically of interest;
1402 .Dv kdb.enter.witness
1403 might be defined to have special handling, and
1404 .Dv kdb.enter.default
1405 might be defined to simply panic and reboot.
1408 On machines with an ISA expansion bus, a simple NMI generation card can be
1409 constructed by connecting a push button between the A01 and B01 (CHCHK# and
1411 Momentarily shorting these two fingers together may cause the bridge chipset to
1412 generate an NMI, which causes the kernel to pass control to
1414 Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary.
1415 The NMI allows one to break into the debugger on a wedged machine to
1417 Other bus' bridge chipsets may be able to generate NMI using bus specific
1420 Header files mention in this manual page can be found below
1430 .Pa netinet/in_pcb.h
1452 debugger was developed for Mach, and ported to
1454 This manual page translated from
1457 .An Garrett Wollman .
1459 .An Robert N. M. Watson