1.\" $NetBSD: ddb.4,v 1.129 2010/01/10 09:08:23 wiz Exp $ 2.\" 3.\" Copyright (c) 1997 - 2009 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Luke Mewburn 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" --- 31.\" This manual page was derived from a -man.old document which bore 32.\" the following copyright message: 33.\" --- 34.\" 35.\" Mach Operating System 36.\" Copyright (c) 1991,1990 Carnegie Mellon University 37.\" All Rights Reserved. 38.\" 39.\" Permission to use, copy, modify and distribute this software and its 40.\" documentation is hereby granted, provided that both the copyright 41.\" notice and this permission notice appear in all copies of the 42.\" software, derivative works or modified versions, and any portions 43.\" thereof, and that both notices appear in supporting documentation. 44.\" 45.\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 46.\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 47.\" ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 48.\" 49.\" Carnegie Mellon requests users of this software to return to 50.\" 51.\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 52.\" School of Computer Science 53.\" Carnegie Mellon University 54.\" Pittsburgh PA 15213-3890 55.\" 56.\" any improvements or extensions that they make and grant Carnegie Mellon 57.\" the rights to redistribute these changes. 58.\" 59.Dd January 10, 2010 60.Dt DDB 4 61.Os 62.Sh NAME 63.Nm ddb 64.Nd in-kernel debugger 65.Sh SYNOPSIS 66.Cd options DDB 67.Pp 68To enable history editing: 69.Cd options DDB_HISTORY_SIZE=integer 70.Pp 71To disable entering 72.\" XXX: hack; .Nm automatically introduces newline in SYNOPSIS 73.Ic ddb 74upon kernel panic: 75.Cd options DDB_ONPANIC=0 76.Pp 77To enable teeing all 78.\" XXX: hack; .Nm automatically introduces newline in SYNOPSIS 79.Ic ddb 80output to the kernel msgbuf: 81.Cd options DDB_TEE_MSGBUF=1 82.Pp 83To specify commands which will be executed on each entry to 84.Ic ddb : 85.Cd options DDB_COMMANDONENTER="trace;show registers" 86In this case, "trace" and then "show registers" will be executed automatically. 87.Pp 88To enable extended online help: 89.Cd options DDB_VERBOSE_HELP . 90.Sh DESCRIPTION 91.Nm 92is the in-kernel debugger. 93It may be entered at any time via a special key sequence, and 94optionally may be invoked when the kernel panics. 95.Sh ENTERING THE DEBUGGER 96Unless 97.Dv DDB_ONPANIC 98is set to 0, 99.Nm 100will be activated whenever the kernel would otherwise panic. 101.Pp 102.Nm 103may also be activated from the console. 104In general, sending a break on a serial console will activate 105.Nm . 106There are also key sequences for each port that will activate 107.Nm 108from the keyboard: 109.Bl -tag -offset indent -width "mvme68k" -compact 110.It alpha 111\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] on PC style keyboards. 112.It amd64 113\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 114.It "" 115\*[Lt]Break\*[Gt] on serial console. 116.It amiga 117\*[Lt]LAlt\*[Gt]-\*[Lt]LAmiga\*[Gt]-\*[Lt]F10\*[Gt] 118.It atari 119\*[Lt]Alt\*[Gt]-\*[Lt]LeftShift\*[Gt]-\*[Lt]F9\*[Gt] 120.It hp300 121\*[Lt]Shift\*[Gt]-\*[Lt]Reset\*[Gt] 122.It hp700 123+++++ 124(five plus signs) 125.It "" 126\*[Lt]Break\*[Gt] on serial console. 127.It hpcarm 128\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 129.It hpcmips 130\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 131.It hpcsh 132\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 133.It i386 134\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 135.It "" 136\*[Lt]Break\*[Gt] on serial console. 137.It mac68k 138\*[Lt]Command\*[Gt]-\*[Lt]Power\*[Gt], or the Interrupt switch. 139.It macppc 140Some models: 141\*[Lt]Command\*[Gt]-\*[Lt]Option\*[Gt]-\*[Lt]Power\*[Gt] 142.It mvme68k 143Abort switch on CPU card. 144.It pmax 145\*[Lt]Do\*[Gt] on 146.Tn LK-201 147rcons console. 148.It "" 149\*[Lt]Break\*[Gt] on serial console. 150.It sparc 151\*[Lt]L1\*[Gt]-A, or \*[Lt]Stop\*[Gt]-A on a 152.Tn Sun 153keyboard. 154.It "" 155\*[Lt]Break\*[Gt] on serial console. 156.It sparc64 157\*[Lt]L1\*[Gt]-A, or \*[Lt]Stop\*[Gt]-A on a 158.Tn Sun 159keyboard. 160.It "" 161\*[Lt]Break\*[Gt] on serial console. 162.It sun3 163\*[Lt]L1\*[Gt]-A, or \*[Lt]Stop\*[Gt]-A on a 164.Tn Sun 165keyboard. 166.It "" 167\*[Lt]Break\*[Gt] on serial console. 168.It vax 169\*[Lt]Esc\*[Gt]-\*[Lt]Shift\*[Gt]-D on serial console. 170.It x68k 171Interrupt switch on the body. 172.It xen 173+++++ 174(five plus signs) 175.It zaurus 176\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 177.El 178.Pp 179The key sequence to activate 180.Nm 181can be changed by modifying 182.Dq hw.cnmagic 183with 184.Xr sysctl 8 . 185If the console is not dedicated to 186.Nm 187the sequence should not be easily typed by accident. 188In addition, 189.Nm 190may be explicitly activated by the debugging code in the kernel 191if 192.Cm DDB 193is configured. 194.Sh COMMAND SYNTAX 195The general command syntax is: 196.Bd -ragged -offset indent 197.Ic command Ns Op Cm / Ns Ar modifier 198.Ar address 199.Op Cm , Ns Ar count 200.Ed 201.Pp 202The current memory location being edited is referred to as 203.Ar dot , 204and the next location is 205.Ar next . 206They are displayed as hexadecimal numbers. 207.Pp 208Commands that examine and/or modify memory update 209.Ar dot 210to the address of the last line examined or the last location 211modified, and set 212.Ar next 213to the next location to be examined or modified. 214Other commands don't change 215.Ar dot , 216and set 217.Ar next 218to be the same as 219.Ar dot . 220.Pp 221A blank line repeats the previous command from the address 222.Ar next 223with the previous 224.Cm count 225and no modifiers. 226Specifying 227.Cm address 228sets 229.Em dot 230to the address. 231If 232.Cm address 233is omitted, 234.Em dot 235is used. 236A missing 237.Cm count 238is taken to be 1 for printing commands, and infinity for stack traces. 239.Pp 240The syntax: 241.Bd -ragged -offset indent 242.Cm , Ns Ar count 243.Ed 244.Pp 245repeats the previous command, just as a blank line does, but with 246the specified 247.Cm count . 248.Pp 249.Nm 250has a 251.Xr more 1 Ns -like 252functionality; if a number of lines in a command's output exceeds the number 253defined in the 254.Va lines 255variable, then 256.Nm 257displays 258.Dq "--db more--" 259and waits for a response, which may be one of: 260.Bl -tag -offset indent -width "\*[Lt]return\*[Gt]" 261.It Aq return 262one more line. 263.It Aq space 264one more page. 265.It Ic q 266abort the current command, and return to the command input mode. 267.El 268.Pp 269You can set 270.Va lines 271variable to zero to disable this feature. 272.Pp 273If 274.Nm 275history editing is enabled (by defining the 276.D1 Cd options DDB_HISTORY_SIZE=num 277kernel option), then a history of the last 278.Cm num 279commands is kept. 280The history can be manipulated with the following key sequences: 281.Bl -tag -offset indent -width "\*[Lt]Ctrl\*[Gt]-P" 282.It \*[Lt]Ctrl\*[Gt]-P 283retrieve previous command in history (if any). 284.It \*[Lt]Ctrl\*[Gt]-N 285retrieve next command in history (if any). 286.El 287.Sh COMMANDS 288.Nm 289supports the following commands: 290.Bl -tag -width 5n 291.It Ic \&! Ns Ar address Ns Oo Cm ( Ar expression Ns Oo Ar ,... Oc Ns Cm ) Oc 292A synonym for 293.Ic call . 294.It Ic break Ns Oo Cm /u Oc Ar address Ns Op Cm , Ns Ar count 295Set a breakpoint at 296.Ar address . 297If 298.Ar count 299is supplied, continues 300.Pq Ar count Ns -1 301times before stopping at the breakpoint. 302If the breakpoint is set, a breakpoint number is printed with 303.Sq \&# . 304This number can be used to 305.Ic delete 306the breakpoint, or to add 307conditions to it. 308.Pp 309If 310.Cm /u 311is specified, 312set a breakpoint at a user-space address. 313Without 314.Cm /u , 315.Ar address 316is considered to be in the kernel-space, and an address in the wrong 317space will be rejected, and an error message will be emitted. 318This modifier may only be used if it is supported by machine dependent 319routines. 320.Pp 321Warning: if a user text is shadowed by a normal user-space debugger, 322user-space breakpoints may not work correctly. 323Setting a breakpoint at the low-level code paths may also cause 324strange behavior. 325.It Ic bt Ns Oo Cm /ul Oc Oo Ar frame-address Oc Ns Oo Cm , Ns Ar count Oc 326A synonym for 327.Ic trace . 328.It Ic bt/t Ns Oo Cm /ul Oc Oo Ar pid Oc Ns Oo Cm , Ns Ar count Oc 329A synonym for 330.Ic trace/t . 331.It Ic bt/a Ns Oo Cm /ul Oc Oo Ar lwpaddr Oc Ns Oo Cm , Ns Ar count Oc 332A synonym for 333.Ic trace/a . 334.It Ic call Ar address Ns Oo Cm ( Ns Ar expression Ns Oo Ar ,... Oc Ns Cm ) Oc 335Call the function specified by 336.Ar address 337with the argument(s) listed in parentheses. 338Parentheses may be omitted if the function takes no arguments. 339The number of arguments is currently limited to 10. 340.It Ic continue Ns Op Cm /c 341Continue execution until a breakpoint or watchpoint. 342If 343.Cm /c 344is specified, count instructions while executing. 345Some machines (e.g., pmax) also count loads and stores. 346.Pp 347Warning: when counting, the debugger is really silently 348single-stepping. 349This means that single-stepping on low-level may cause strange 350behavior. 351.It Ic delete Ar "address" | Cm # Ns Ar number 352Delete a breakpoint. 353The target breakpoint may be specified by 354.Ar address , 355as per 356.Ic break , 357or by the breakpoint number returned by 358.Ic break 359if it's prefixed with 360.Sq Cm \&# . 361.It Ic dmesg Op Ar count 362Prints the contents of the kernel message buffer. 363The optional 364.Ar count 365argument will limit printing to at most the last 366.Ar count 367bytes of the message buffer. 368.It Ic dwatch Ar address 369Delete the watchpoint at 370.Ar address 371that was previously set with 372.Ic watch 373command. 374.It Ic examine Ns Oo Cm / Ns Ar modifier Oc Ar address Ns Op Cm , Ns Ar count 375Display the address locations according to the format in 376.Ar modifier . 377Multiple modifier formats display multiple locations. 378If 379.Ar modifier 380isn't specified, the modifier from the last use of 381.Ic examine 382is used. 383.Pp 384The valid format characters for 385.Ar modifier 386are: 387.Bl -tag -offset indent -width 2n -compact 388.It Cm b 389examine bytes (8 bits). 390.It Cm h 391examine half-words (16 bits). 392.It Cm l 393examine words (legacy 394.Dq long , 39532 bits). 396.It Cm L 397examine long words (implementation dependent) 398.It Cm a 399print the location being examined. 400.It Cm A 401print the location with a line number if possible. 402.It Cm x 403display in unsigned hex. 404.It Cm z 405display in signed hex. 406.It Cm o 407display in unsigned octal. 408.It Cm d 409display in signed decimal. 410.It Cm u 411display in unsigned decimal. 412.It Cm r 413display in current radix, signed. 414.It Cm c 415display low 8 bits as a character. 416Non-printing characters as displayed as an octal escape code 417(e.g., 418.Sq \e000 ) . 419.It Cm s 420display the NUL terminated string at the location. 421Non-printing characters are displayed as octal escapes. 422.It Cm m 423display in unsigned hex with a character dump at the end of each line. 424The location is displayed as hex at the beginning of each line. 425.It Cm i 426display as a machine instruction. 427.It Cm I 428display as a machine instruction, with possible alternative formats 429depending upon the machine: 430.Bl -tag -offset indent -width "sparc" -compact 431.It alpha 432print register operands 433.It m68k 434use Motorola syntax 435.It vax 436don't assume that each external label is a procedure entry mask 437.El 438.El 439.It Ic kill Ar pid Ns Op Cm , Ns Ar signal_number 440Send a signal to the process specified by the 441.Ar pid . 442Note that 443.Ar pid 444is interpreted using the current radix (see 445.Cm trace/t 446command for details). 447If 448.Ar signal_number 449isn't specified, the SIGTERM signal is sent. 450.It Ic match Ns Op Cm /p 451A synonym for 452.Ic next . 453.It Ic next Ns Op Cm /p 454Stop at the matching return instruction. 455If 456.Cm /p 457is specified, print the call nesting depth and the 458cumulative instruction count at each call or return. 459Otherwise, only print when the matching return is hit. 460.It Ic print Ns Oo Cm /axzodurc Oc Ar address Op Ar address ... 461Print addresses 462.Ar address 463according to the modifier character, as per 464.Ic examine . 465Valid modifiers are: 466.Cm /a , 467.Cm /x , 468.Cm /z , 469.Cm /o , 470.Cm /d , 471.Cm /u , 472.Cm /r , 473and 474.Cm /c 475(as per 476.Ic examine ) . 477If no modifier is specified, the most recent one specified is used. 478.Ar address 479may be a string, and is printed 480.Dq as-is . 481For example: 482.Bd -literal -offset indent 483print/x "eax = " $eax "\enecx = " $ecx "\en" 484.Ed 485.Pp 486will produce: 487.Bd -literal -offset indent 488eax = xxxxxx 489ecx = yyyyyy 490.Ed 491.It Ic ps Ns Oo Cm /a Oc Ns Oo Cm /n Oc Ns Oo Cm /w Oc Ns Oo Cm /l Oc 492A synonym for 493.Ic show all procs . 494.It Ic reboot Op Ar flags 495Reboot, using the optionally supplied boot 496.Ar flags , 497which is a bitmask supporting the same values as for 498.Xr reboot 2 . 499Some of the more useful flags: 500.Bl -column "Value" "RB_POWERDOWN" "Description" 501.It Sy "Value" Ta Sy "Name" Ta Sy "Description" 502.It 0x1 Ta RB_ASKNAME Ta Ask for file name to reboot from 503.It 0x2 Ta RB_SINGLE Ta Reboot to single user mode 504.It 0x4 Ta RB_NOSYNC Ta Don't sync before reboot 505.It 0x8 Ta RB_HALT Ta Halt instead of reboot 506.It 0x40 Ta RB_KDB Ta Boot into kernel debugger 507.It 0x100 Ta RB_DUMP Ta Dump unconditionally before reboot 508.It 0x808 Ta RB_POWERDOWN Ta Power off (or at least halt) 509.El 510.Pp 511Note: Limitations of the command line interface preclude 512specification of a boot string. 513.It Ic search Ns Oo Cm /bhl Oc Ar address Ar value \ 514Oo Ar mask Oc Oo Cm , Ns Ar count Oc 515Search memory from 516.Ar address 517for 518.Ar value . 519The unit size is specified with a modifier character, as per 520.Ic examine . 521Valid modifiers are: 522.Cm /b , 523.Cm /h , 524and 525.Cm /l . 526If no modifier is specified, 527.Cm /l 528is used. 529.Pp 530This command might fail in interesting ways if it doesn't find 531.Ar value . 532This is because 533.Nm 534doesn't always recover from touching bad memory. 535The optional 536.Ar count 537limits the search. 538.It Ic set Cm $ Ns Ar variable Oo Cm = Oc Ar expression 539Set the named variable or register to the value of 540.Ar expression . 541Valid variable names are described in 542.Sx VARIABLES . 543.It Ic show all callout 544Display information about callouts in the system. 545See 546.Xr callout 9 547for more information on callouts. 548.It Ic show all pages 549Display basic information about all physical pages managed by the VM system. 550For more detailed information about a single page, use 551.Ic show page . 552.It Ic show all pools Ns Op Cm /clp 553Display all pool information. 554Modifiers are the same as 555.Ic show pool . 556.It Ic "show\ all\ procs" Ns Oo Cm /a Oc Ns Oo Cm /n Oc Ns Oo Cm /w Oc Ns \ 557Oo Cm /l Oc 558Display all process information. 559Valid modifiers: 560.Bl -tag -width 3n 561.It Cm /n 562show process information in a 563.Xr ps 1 564style format. 565Information printed includes: process ID, parent process ID, 566process group, UID, process status, process flags, process 567command name, and process wait channel message. 568.It Cm /a 569show the kernel virtual addresses of each process' 570proc structure, u-area, and vmspace structure. 571The vmspace address is also the address of the process' 572vm_map structure, and can be used in the 573.Ic show map 574command. 575.It Cm /w 576show each process' PID, command, system call emulation, wait channel 577address, and wait channel message. 578.It Cm /l 579show each process' associated LWP information, including each LWP's 580LID, flags, kernel LWP structure address, u-area, and wait channel. 581This is the default. 582.El 583.It Ic show arptab 584Dump the entire 585.Dv AF_INET 586routing table. 587This command is available only on systems which support inet and ARP. 588.It Ic show breaks 589Display all breakpoints. 590.It Ic show buf Ns Oo Cm /f Oc Ar address 591Print the struct buf at 592.Ar address . 593The 594.Cm /f 595does nothing at this time. 596.It Ic show event Ns Oo Cm /f Oc Ns Oo Cm /i Oc Ns Oo Cm /m Oc Ns \ 597Oo Cm /t Oc 598Print all the non-zero 599.Xr evcnt 9 600event counters. 601Valid modifiers: 602.Bl -tag -width 3n 603.It Cm /f 604event counters with a count of zero are printed as well. 605.It Cm /i 606interrupted counters will be displayed. 607.It Cm /m 608misc counters will be displayed. 609.It Cm /t 610trap counters will be displayed. 611.El 612.Pp 613If none of 614.Cm /i , 615.Cm /m 616or 617.Cm /t 618are specified, all are shown. 619You can combine any of these. 620For example, the modifier 621.Cm /itf 622will select both interrupt and trap events, including those that are non-zero. 623.It Ic show files Ar address 624Display information about the vnodes of the files that are currently 625open by the process associated with the proc structure at 626.Ar address . 627This address can be found using the 628.Ic show all procs /a 629command. 630If the kernel is compiled with 631.Cd options LOCKDEBUG 632then details about the locking of the underlying uvm object will also 633be displayed. 634.It Ic show lock Ar address 635Display information about a lock at 636.Ar address . 637This command is useful only if a kernel is compiled with 638.Cd options LOCKDEBUG . 639.It Ic show malloc Ar address 640If 641.Ar address 642is supplied, display the kernel memory allocator's idea on the 643allocation status for it. 644Also, print out global statistics for the memory allocator. 645This command is useful only if a kernel is compiled with 646.Cd options MALLOC_DEBUG . 647.It Ic show map Ns Oo Cm /f Oc Ar address 648Print the vm_map at 649.Ar address . 650If 651.Cm /f 652is specified, the complete map is printed. 653.It Ic show mount Ns Oo Cm /f Oc Ar address 654Print the mount structure at 655.Ar address . 656If 657.Cm /f 658is specified, the complete vnode list is printed. 659.It Ic show mbuf Ns Oo Cm /c Oc Ar address 660Print the mbuf structure at 661.Ar address . 662If 663.Cm /c 664is specified, the mbufs in the chain are followed. 665.It Ic show ncache Ar address 666Dump the namecache list associated with vnode at 667.Ar address . 668.It Ic show object Ns Oo Cm /f Oc Ar address 669Print the vm_object at 670.Ar address . 671If 672.Cm /f 673is specified, the complete object is printed. 674.It Ic show page Ns Oo Cm /f Oc Ar address 675Print the vm_page at 676.Ar address . 677If 678.Cm /f 679is specified, the complete page is printed. 680.It Ic show pool Ns Oo Cm /clp Oc Ar address 681Print the pool at 682.Ar address . 683Valid modifiers: 684.Bl -tag -width 4n -compact 685.It Cm /c 686Print the cachelist and its statistics for this pool. 687.It Cm /l 688Print the log entries for this pool. 689.It Cm /p 690Print the pagelist for this pool. 691.El 692.It Ic show registers Ns Op Cm /u 693Display the register set. 694If 695.Cm /u 696is specified, display user registers instead of kernel registers 697or the currently save one. 698.Pp 699Warning: support for 700.Cm /u 701is machine dependent. 702If not supported, incorrect information will be displayed. 703.It Ic show sched_qs 704Print the state of the scheduler's run queues. 705For each run queue that has an LWP, the run queue index and the list 706of LWPs will be shown. 707If the run queue has LWPs, but the sched_whichqs bit is not set for that 708queue, the queue index will be prefixed with a 709.Sq \&! . 710.It Ic show uvmexp 711Print a selection of UVM counters and statistics. 712.It Ic show uvmhist 713Dumps the UVM histories. 714This command is available only if a kernel is compiled with 715.Cd options UVMHIST . 716.It Ic show vnode Ns Oo Cm /f Oc Ar address 717Print the vnode at 718.Ar address . 719If 720.Cm /f 721is specified, the complete vnode is printed. 722.It Ic show watches 723Display all watchpoints. 724.It Ic sifting Ns Oo Cm /F Oc Ar string 725Search the symbol tables for all symbols of which 726.Ar string 727is a substring, and display them. 728If 729.Cm /F 730is specified, a character is displayed immediately after each symbol 731name indicating the type of symbol. 732.Pp 733For 734.Xr a.out 5 Ns -format 735symbol tables, 736absolute symbols display 737.Sy @ , 738text segment symbols display 739.Sy * , 740data segment symbols display 741.Sy + , 742.Tn BSS 743segment symbols display 744.Sy - , 745and filename symbols display 746.Sy / . 747For 748.Tn ELF Ns -format 749symbol tables, 750object symbols display 751.Sy + , 752function symbols display 753.Sy * , 754section symbols display 755.Sy \*[Am] , 756and file symbols display 757.Sy / . 758.Pp 759To sift for a string beginning with a number, escape the first 760character with a backslash as: 761.Bd -literal -offset indent 762sifting \\386 763.Ed 764.It Ic step Ns Oo Cm /p Oc Op Cm , Ns Ar count 765Single-step 766.Ar count 767times. 768If 769.Cm /p 770is specified, print each instruction at each step. 771Otherwise, only print the last instruction. 772.Pp 773Warning: depending on the machine type, it may not be possible 774to single-step through some low-level code paths or user-space 775code. 776On machines with software-emulated single-stepping (e.g., pmax), 777stepping through code executed by interrupt handlers will probably 778do the wrong thing. 779.It Ic sync 780Force a crash dump, and then reboot. 781.It Ic trace Ns Oo Cm /u Ns Oo Cm l Oc Oc Oo Ar frame-address Oc Ns \ 782Oo Cm , Ns Ar count Oc 783Stack trace from 784.Ar frame-address . 785If 786.Cm /u 787is specified, trace user-space, otherwise trace kernel-space. 788.Ar count 789is the number of frames to be traced. 790If 791.Ar count 792is omitted, all frames are printed. 793If 794.Cm /l 795is specified, the trace is printed and also stored in the kernel 796message buffer. 797.Pp 798Warning: user-space stack trace is valid only if the machine dependent 799code supports it. 800.It Ic trace/t Ns Oo Cm l Oc Oo Ar pid Oc Ns Oo Cm , Ns Ar count Oc 801Stack trace by 802.Dq thread 803(process, on 804.Nx ) 805rather than by stack frame address. 806Note that 807.Ar pid 808is interpreted using the current radix, whilst 809.Ic ps 810displays pids in decimal; prefix 811.Ar pid 812with 813.Sq 0t 814to force it to be interpreted as decimal (see 815.Sx VARIABLES 816section for radix). 817If 818.Cm /l 819is specified, the trace is printed and also stored in the kernel 820message buffer. 821.Pp 822Warning: trace by pid is valid only if the machine dependent code 823supports it. 824.It Ic trace/a Ns Oo Cm l Oc Oo Ar lwpaddr Oc Ns Oo Cm , Ns Ar count Oc 825Stack trace by light weight process (LWP) address 826rather than by stack frame address. 827If 828.Cm /l 829is specified, the trace is printed and also stored in the kernel 830message buffer. 831.Pp 832Warning: trace by LWP address is valid only if the machine dependent 833code supports it. 834.It Ic until Ns Op Cm /p 835Stop at the next call or return instruction. 836If 837.Cm /p 838is specified, print the call nesting depth and the 839cumulative instruction count at each call or return. 840Otherwise, only print when the matching return is hit. 841.It Ic watch Ar address Ns Oo Cm , Ns Ar size Oc 842Set a watchpoint for a region. 843Execution stops when an attempt to modify the region occurs. 844.Ar size 845defaults to 4. 846.Pp 847If you specify a wrong space address, the request is 848rejected with an error message. 849.Pp 850Warning: attempts to watch wired kernel memory may cause 851an unrecoverable error in some systems such as i386. 852Watchpoints on user addresses work the best. 853.It Ic whatis Ar address 854Describe what an address is. 855.It Ic write Ns Oo Cm /bhl Oc Ar address Ar expression Oo Ar expression ... Oc 856Write the 857.Ar expression Ns s 858at succeeding locations. 859The unit size is specified with a modifier character, as per 860.Ic examine . 861Valid modifiers are: 862.Cm /b , 863.Cm /h , 864and 865.Cm /l . 866If no modifier is specified, 867.Cm /l 868is used. 869.Pp 870Warning: since there is no delimiter between 871.Ar expression Ns s , 872strange things may occur. 873It's best to enclose each 874.Ar expression 875in parentheses. 876.It Ic x Ns Oo Cm / Ns Ar modifier Oc Ar address Ns Op Cm , Ns Ar count 877A synonym for 878.Ic examine . 879.\" XXX - these commands aren't implemented; jhawk 19 May 2000 880.\" .It Ic xf 881.\" Examine forward. 882.\" .Ic xf 883.\" re-executes the most recent 884.\" .Ic execute 885.\" command with the same parameters except that 886.\" .Ar address 887.\" is set to 888.\" .Ar next . 889.\" .It Ic xb 890.\" Examine backward. 891.\" .Ic xb 892.\" re-executes the most recent 893.\" .Ic execute 894.\" command with the same parameters, except that 895.\" .Ar address 896.\" is set to the last start address minus its size. 897.El 898.Sh MACHINE-SPECIFIC COMMANDS 899The "glue" code that hooks 900.Nm 901into the 902.Nx 903kernel for any given port can also add machine specific commands 904to the 905.Nm 906command parser. 907All of these commands are preceded by the command word 908.Em machine 909to indicate that they are part of the machine-specific command 910set (e.g. 911.Ic machine reboot ) . 912Some of these commands are: 913.Ss ALPHA 914.Bl -tag -width "traptrace" -compact 915.It Ic halt 916Call the PROM monitor to halt the CPU. 917.It Ic reboot 918Call the PROM monitor to reboot the CPU. 919.El 920.Ss ARM32 921.Bl -tag -width "traptrace" -compact 922.It Ic panic 923Print the current "panic" string. 924.It Ic frame 925Given a trap frame address, print out the trap frame. 926.El 927.Ss MIPS 928.Bl -tag -width "traptrace" -compact 929.It Ic cp0 930Dump CP0 (coprocessor 0) register values. 931.It Ic kvtop 932Print the physical address for a given kernel virtual address. 933.It Ic tlb 934Print out the Translation Lookaside Buffer (TLB). 935Only works in 936.Nx 937kernels compiled with 938.Dv DEBUG 939option. 940.El 941.Ss SH3 942.Bl -tag -width "traptrace" -compact 943.It Ic tlb 944Print TLB entries 945.It Ic cache 946Print cache entries 947.It Ic frame 948Print switch frame and trap frames. 949.It Ic stack 950Print kernel stack usage. 951Only works in 952.Nx 953kernels compiled with the 954.Dv KSTACK_DEBUG 955option. 956.El 957.Ss SPARC 958.Bl -tag -width "traptrace" -compact 959.It Ic cpu 960Switch to another cpu. 961.It Ic prom 962Enter the Sun PROM monitor. 963.It Ic proc 964Display some information about the LWP pointed to, or curlwp. 965.It Ic pcb 966Display information about the 967.Dq struct pcb 968listed. 969.It Ic page 970Display the pointer to the 971.Dq struct vm_page 972for this physical address. 973.El 974.Ss SPARC64 975.Bl -tag -width "traptrace" -compact 976.It Ic ctx 977Print process context information. 978.It Ic cpu 979Switch to another cpu. 980.It Ic dtlb 981Print data translation look-aside buffer context information. 982.It Ic dtsb 983Display data translation storage buffer information. 984.It Ic kmap 985Display information about the listed mapping in the kernel pmap. 986Use the 987.Dq f 988modifier to get a full listing. 989.It Ic extract 990Extract the physical address for a given virtual address from the kernel pmap. 991.It Ic fpstate 992Dump the FPU state. 993.It Ic itlb 994Print instruction translation look-aside buffer context information. 995.It Ic itsb 996Display instruction translation storage buffer information. 997.It Ic lwp 998Display a struct lwp 999.It Ic pcb 1000Display information about the 1001.Dq struct pcb 1002listed. 1003.It Ic pctx 1004Attempt to change process context. 1005.It Ic page 1006Display the pointer to the 1007.Dq struct vm_page 1008for this physical address. 1009.It Ic phys 1010Display physical memory. 1011.It Ic pmap 1012Display the pmap. 1013Use the 1014.Dq f 1015modifier to get a fuller listing. 1016.It Ic proc 1017Display some information about the process pointed to, or curproc. 1018.It Ic prom 1019Enter the OFW PROM. 1020.It Ic pv 1021Display the 1022.Dq struct pv_entry 1023pointed to. 1024.It Ic sir 1025Reset the machine and enter prom (do a Software Initiated Reset). 1026.It Ic stack 1027Dump the window stack. 1028Use the 1029.Dq u 1030modifier to get userland information. 1031.It Ic tf 1032Display full trap frame state. 1033This is most useful for inclusion with bug reports. 1034.It Ic ts 1035Display trap state. 1036.It Ic traptrace 1037Display or set trap trace information. 1038Use the 1039.Dq r 1040and 1041.Dq f 1042modifiers to get reversed and full information, respectively. 1043.It Ic watch 1044Set or clear a physical or virtual hardware watchpoint. 1045Pass the address to be watched, or 1046.Dq 0 1047(or omit the address) to clear the watchpoint. 1048Optional modifiers are 1049.Dq p 1050for physical address, 1051.Dq r 1052for trap on read access (default: trap on write access only), 1053.Dq b 1054for 8 bit width, 1055.Dq h 1056for 16 bit, 1057.Dq l 1058for 32 bit or 1059.Dq L 1060for 64 bit. 1061.It Ic window 1062Print register window information. 1063Argument is a stack frame number (0 is 1064top of stack, which is used when no index is given). 1065.El 1066.Ss SUN3 and SUN3X 1067.Bl -tag -width "traptrace" -compact 1068.It Ic abort 1069Drop into monitor via abort (allows continue). 1070.It Ic halt 1071Exit to Sun PROM monitor as in 1072.Xr halt 8 . 1073.It Ic reboot 1074Reboot the machine as in 1075.Xr reboot 8 . 1076.It Ic pgmap 1077Given an address, print the address, segment map, page map, and 1078Page Table Entry (PTE). 1079.El 1080.Sh VARIABLES 1081.Nm 1082accesses registers and variables as 1083.Cm $ Ns Ar name . 1084Register names are as per the 1085.Ic show registers 1086command. 1087Some variables are suffixed with numbers, and may have a modifier 1088following a colon immediately after the variable name. 1089For example, register variables may have a 1090.Sq u 1091modifier to indicate user register 1092(e.g., 1093.Li "$eax:u" ) . 1094.Pp 1095Built-in variables currently supported are: 1096.Bl -tag -offset indent -width "maxwidth" -compact 1097.It Va lines 1098The number of lines. 1099This is used by the 1100.Ic more 1101feature. 1102When this variable is set to zero the 1103.Ic more 1104feature is disabled. 1105.It Va maxoff 1106Addresses are printed as 1107.Li 'symbol'+offset 1108unless 1109.Li offset 1110is greater than 1111.Va maxoff . 1112.It Va maxwidth 1113The width of the displayed line. 1114.Nm 1115wraps the current line by printing new line when 1116.Va maxwidth 1117column is reached. 1118When this variable is set to zero 1119.Nm 1120doesn't perform any wrapping. 1121.It Va onpanic 1122If non-zero (the default), 1123.Nm 1124will be invoked when the kernel panics. 1125If the kernel configuration option 1126.D1 Cd options DDB_ONPANIC=0 1127is used, 1128.Va onpanic 1129will be initialized to off. 1130.It Va fromconsole 1131If non-zero (the default), 1132the kernel allows to enter 1133.Nm 1134from the console (by break signal or special key sequence). 1135If the kernel configuration option 1136.D1 Cd options DDB_FROMCONSOLE=0 1137is used, 1138.Va fromconsole 1139will be initialized to off. 1140.It Va radix 1141Input and output radix. 1142.It Va tabstops 1143Tab stop width. 1144.It Va tee_msgbuf 1145If explicitly set to non zero (zero is the default) all 1146.Nm 1147output will not only be displayed on screen but 1148also be fed to the msgbuf. 1149The default of the variable can be set using the kernel configuration option 1150.D1 Cd options DDB_TEE_MSGBUF=1 1151which will initialize 1152.Va tee_msgbuf 1153to be 1. 1154This option is especially handy for poor souls 1155who don't have a serial console but want to recall 1156.Nm 1157output from a crash investigation. 1158This option is more generic than the /l command modifier possible for 1159selected commands as discussed above to log the output. 1160Mixing both /l 1161and this setting can give double loggings. 1162.\" .It Va work Ns Sy xx 1163.\" Temporary work variable. 1164.\" .Sq Sy xx 1165.\" is between 0 and 31. 1166.El 1167.Pp 1168All built-in variables are accessible via 1169.Xr sysctl 3 . 1170.Sh EXPRESSIONS 1171Almost all expression operators in C are supported, except 1172.Sq \&~ , 1173.Sq \&^ , 1174and unary 1175.Sq \&\*[Am] . 1176Special rules in 1177.Nm 1178are: 1179.Bl -tag -offset indent -width "identifier" 1180.It Ar identifier 1181name of a symbol. 1182It is translated to the address (or value) of it. 1183.Sq \&. 1184and 1185.Sq \&: 1186can be used in the identifier. 1187If supported by an object format dependent routine, 1188.Sm off 1189.Xo 1190.Oo Ar filename : Oc 1191.Ar function 1192.Oo : Ar line\ number Oc , 1193.Xc 1194.Sm on 1195.Sm off 1196.Xo 1197.Oo Ar filename : Oc 1198.Ar variable , 1199.Xc 1200.Sm on 1201and 1202.Sm off 1203.Xo 1204.Ar filename 1205.Oo : Ar "line number" Oc , 1206.Xc 1207.Sm on 1208can be accepted as a symbol. 1209The symbol may be prefixed with 1210.Ar symbol_table_name\^ : : 1211(e.g., 1212.Li emulator::mach_msg_trap ) 1213to specify other than kernel symbols. 1214.It Ar number 1215number. 1216Radix is determined by the first two characters: 1217.Sq 0x 1218- hex, 1219.Sq 0o 1220- octal, 1221.Sq 0t 1222- decimal, 1223otherwise follow current radix. 1224.It Cm . 1225.Ar dot 1226.It Cm + 1227.Ar next 1228.It Cm .. 1229address of the start of the last line examined. 1230Unlike 1231.Ar dot 1232or 1233.Ar next , 1234this is only changed by the 1235.Ic examine 1236or 1237.Ic write 1238commands. 1239.It Cm \&" \"" XXX: emacs highlighting 1240last address explicitly specified. 1241.It Cm $ Ns Ar name 1242register name or variable. 1243It is translated to the value of it. 1244It may be followed by a 1245.Sq \&: 1246and modifiers as described above. 1247.It Cm # 1248a binary operator which rounds up the left hand side to the next 1249multiple of right hand side. 1250.It Cm * Ns Ar expr 1251expression indirection. 1252It may be followed by a 1253.Sq \&: 1254and modifiers as described above. 1255.El 1256.Sh SEE ALSO 1257.Xr reboot 2 , 1258.Xr options 4 , 1259.Xr crash 8 , 1260.Xr reboot 8 , 1261.Xr sysctl 8 , 1262.Xr cnmagic 9 1263.Sh HISTORY 1264The 1265.Nm 1266kernel debugger was written as part of the MACH project at 1267Carnegie-Mellon University. 1268