1.\" $NetBSD: ddb.4,v 1.170 2017/12/28 23:16:42 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 December 28, 2017 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 "xen domU" -compact 110.It alpha 111<Ctrl>-<Alt>-<Esc> on PC style keyboards. 112.It amd64 113<Ctrl>-<Alt>-<Esc> 114.It "" 115<Break> on serial console. 116.It amiga 117<LAlt>-<LAmiga>-<F10> 118.It atari 119<Alt>-<LeftShift>-<F9> 120.It hp300 121<Shift>-<Reset> 122.It hpcarm 123<Ctrl>-<Alt>-<Esc> 124.It hpcmips 125<Ctrl>-<Alt>-<Esc> 126.It hpcsh 127<Ctrl>-<Alt>-<Esc> 128.It hppa 129<Ctrl>-<Alt>-<Esc> on PC style keyboards. 130.It "" 131+++++ 132(five plus signs) on PDC console 133.It "" 134<Break> on serial console. 135.It i386 136<Ctrl>-<Alt>-<Esc> 137.It "" 138<Break> on serial console. 139.It mac68k 140<Command>-<Power>, or the Interrupt switch. 141.It macppc 142Some models: 143<Command>-<Option>-<Power> 144.It mvme68k 145Abort switch on CPU card. 146.It pmax 147<Do> on LK-201 rcons console. 148.It "" 149<Break> on serial console. 150.It sandpoint 151<Break> on serial console. 152.It sparc 153<L1>-A, or <Stop>-A on a Sun keyboard. 154.It "" 155<Break> on serial console. 156.It sparc64 157<L1>-A, or <Stop>-A on a Sun keyboard. 158.It "" 159<Break> on serial console. 160.It sun3 161<L1>-A, or <Stop>-A on a Sun keyboard. 162.It "" 163<Break> on serial console. 164.It vax 165<Esc>-<Shift>-D on serial console. 166.It x68k 167Interrupt switch on the body. 168.It xen dom0 169<Ctrl>-<Alt>-<Esc> on PC style keyboards. 170.It "" 171+++++ 172(five plus signs) on serial console. 173.It xen domU 174+++++ 175(five plus signs) on serial console. 176.It zaurus 177<Ctrl>-<Alt>-<Esc> 178.El 179.Pp 180The key sequence to activate 181.Nm 182can be changed by modifying 183.Dq hw.cnmagic 184with 185.Xr sysctl 8 . 186If the console is not dedicated to 187.Nm 188the sequence should not be easily typed by accident. 189In addition, 190.Nm 191may be explicitly activated by the debugging code in the kernel 192if 193.Cm DDB 194is configured. 195.Pp 196Commands can be automatically run when 197.Nm 198is entered by using 199.Cd options DDB_COMMANDONENTER 200or by setting 201.Ar ddb.commandonenter 202with 203.Xr sysctl 8 . 204Multiple commands can be separated by a semi-colon. 205.Sh COMMAND SYNTAX 206The general command syntax is: 207.Bd -ragged -offset indent 208.Ic command Ns Op Cm / Ns Ar modifier 209.Ar address 210.Op Cm , Ns Ar count 211.Ed 212.Pp 213The current memory location being edited is referred to as 214.Ar dot , 215and the next location is 216.Ar next . 217They are displayed as hexadecimal numbers. 218.Pp 219Commands that examine and/or modify memory update 220.Ar dot 221to the address of the last line examined or the last location 222modified, and set 223.Ar next 224to the next location to be examined or modified. 225Other commands don't change 226.Ar dot , 227and set 228.Ar next 229to be the same as 230.Ar dot . 231.Pp 232A blank line repeats the previous command from the address 233.Ar next 234with the previous 235.Cm count 236and no modifiers. 237Specifying 238.Cm address 239sets 240.Em dot 241to the address. 242If 243.Cm address 244is omitted, 245.Em dot 246is used. 247A missing 248.Cm count 249is taken to be 1 for printing commands, and infinity for stack traces. 250.Pp 251The syntax: 252.Bd -ragged -offset indent 253.Cm , Ns Ar count 254.Ed 255.Pp 256repeats the previous command, just as a blank line does, but with 257the specified 258.Cm count . 259.Pp 260.Nm 261has a 262.Xr more 1 Ns -like 263functionality; if a number of lines in a command's output exceeds the number 264defined in the 265.Va lines 266variable, then 267.Nm 268displays 269.Dq "--db more--" 270and waits for a response, which may be one of: 271.Bl -tag -offset indent -width "<return>" 272.It Aq return 273one more line. 274.It Aq space 275one more page. 276.It Ic q 277abort the current command, and return to the command input mode. 278.El 279.Pp 280You can set 281.Va lines 282variable to zero to disable this feature. 283.Pp 284If 285.Nm 286history editing is enabled (by defining the 287.D1 Cd options DDB_HISTORY_SIZE=num 288kernel option), then a history of the last 289.Cm num 290commands is kept. 291The history can be manipulated with the following key sequences: 292.Bl -tag -offset indent -width "<Ctrl>-P" 293.It <Ctrl>-P 294retrieve previous command in history (if any). 295.It <Ctrl>-N 296retrieve next command in history (if any). 297.El 298.Sh COMMANDS 299.Nm 300supports the following commands: 301.Bl -tag -width 5n 302.It Ic \&! Ns Ar address Ns Oo Cm ( Ar expression Ns Oo Ar ,... Oc Ns Cm ) Oc 303A synonym for 304.Ic call . 305.It Ic break Ns Oo Cm /u Oc Ar address Ns Op Cm , Ns Ar count 306Set a breakpoint at 307.Ar address . 308If 309.Ar count 310is supplied, continues 311.Pq Ar count Ns \-1 312times before stopping at the breakpoint. 313If the breakpoint is set, a breakpoint number is printed with 314.Sq \&# . 315This number can be used to 316.Ic delete 317the breakpoint, or to add 318conditions to it. 319.Pp 320If 321.Cm /u 322is specified, 323set a breakpoint at a user-space address. 324Without 325.Cm /u , 326.Ar address 327is considered to be in the kernel-space, and an address in the wrong 328space will be rejected, and an error message will be emitted. 329This modifier may only be used if it is supported by machine dependent 330routines. 331.Pp 332Warning: if a user text is shadowed by a normal user-space debugger, 333user-space breakpoints may not work correctly. 334Setting a breakpoint at the low-level code paths may also cause 335strange behavior. 336.It Ic bt Ns Oo Cm /ul Oc Oo Ar frame-address Oc Ns Oo Cm , Ns Ar count Oc 337A synonym for 338.Ic trace . 339.It Ic bt/t Ns Oo Cm /ul Oc Oo Ar pid Oc Ns Oo Cm , Ns Ar count Oc 340A synonym for 341.Ic trace/t . 342.It Ic bt/a Ns Oo Cm /ul Oc Oo Ar lwpaddr Oc Ns Oo Cm , Ns Ar count Oc 343A synonym for 344.Ic trace/a . 345.It Ic call Ar address Ns Oo Cm ( Ns Ar expression Ns Oo Ar ,... Oc Ns Cm ) Oc 346Call the function specified by 347.Ar address 348with the argument(s) listed in parentheses. 349Parentheses may be omitted if the function takes no arguments. 350The number of arguments is currently limited to 10. 351.It Ic continue Ns Op Cm /c 352Continue execution until a breakpoint or watchpoint. 353If 354.Cm /c 355is specified, count instructions while executing. 356Some machines (e.g., pmax) also count loads and stores. 357.Pp 358Warning: when counting, the debugger is really silently 359single-stepping. 360This means that single-stepping on low-level may cause strange 361behavior. 362.It Ic delete Ar "address" | Cm # Ns Ar number 363Delete a breakpoint. 364The target breakpoint may be specified by 365.Ar address , 366as per 367.Ic break , 368or by the breakpoint number returned by 369.Ic break 370if it's prefixed with 371.Sq Cm \&# . 372.It Ic dmesg Op Ar count 373Prints the contents of the kernel message buffer. 374The optional 375.Ar count 376argument will limit printing to at most the last 377.Ar count 378bytes of the message buffer. 379.It Ic dwatch Ar address 380Delete the watchpoint at 381.Ar address 382that was previously set with 383.Ic watch 384command. 385.It Ic examine Ns Oo Cm / Ns Ar modifier Oc Ar address Ns Op Cm , Ns Ar count 386Display the address locations according to the format in 387.Ar modifier . 388Multiple modifier formats display multiple locations. 389If 390.Ar modifier 391isn't specified, the modifier from the last use of 392.Ic examine 393is used. 394.Pp 395The valid format characters for 396.Ar modifier 397are: 398.Bl -tag -offset indent -width 2n -compact 399.It Cm b 400examine bytes (8 bits). 401.It Cm h 402examine half-words (16 bits). 403.It Cm l 404examine words (legacy 405.Dq long , 40632 bits). 407.It Cm L 408examine long words (implementation dependent) 409.It Cm a 410print the location being examined. 411.It Cm A 412print the location with a line number if possible. 413.It Cm x 414display in unsigned hex. 415.It Cm z 416display in signed hex. 417.It Cm o 418display in unsigned octal. 419.It Cm d 420display in signed decimal. 421.It Cm u 422display in unsigned decimal. 423.It Cm r 424display in current radix, signed. 425.It Cm c 426display low 8 bits as a character. 427Non-printing characters as displayed as an octal escape code 428(e.g., 429.Sq \e000 ) . 430.It Cm s 431display the NUL terminated string at the location. 432Non-printing characters are displayed as octal escapes. 433.It Cm m 434display in unsigned hex with a character dump at the end of each line. 435The location is displayed as hex at the beginning of each line. 436.It Cm i 437display as a machine instruction. 438.It Cm I 439display as a machine instruction, with possible alternative formats 440depending upon the machine: 441.Bl -tag -offset indent -width "sparc" -compact 442.It alpha 443print register operands 444.It m68k 445use Motorola syntax 446.It vax 447don't assume that each external label is a procedure entry mask 448.El 449.El 450.It Ic kill Ar pid Ns Op Cm , Ns Ar signal_number 451Send a signal to the process specified by the 452.Ar pid . 453Note that 454.Ar pid 455is interpreted using the current radix (see 456.Cm trace/t 457command for details). 458If 459.Ar signal_number 460isn't specified, the SIGTERM signal is sent. 461.It Ic match Ns Op Cm /p 462A synonym for 463.Ic next . 464.It Ic next Ns Op Cm /p 465Stop at the matching return instruction. 466If 467.Cm /p 468is specified, print the call nesting depth and the 469cumulative instruction count at each call or return. 470Otherwise, only print when the matching return is hit. 471.It Ic print Ns Oo Cm /axzodurc Oc Ar address Op Ar address ... 472Print addresses 473.Ar address 474according to the modifier character, as per 475.Ic examine . 476Valid modifiers are: 477.Cm /a , 478.Cm /x , 479.Cm /z , 480.Cm /o , 481.Cm /d , 482.Cm /u , 483.Cm /r , 484and 485.Cm /c 486(as per 487.Ic examine ) . 488If no modifier is specified, the most recent one specified is used. 489.Ar address 490may be a string, and is printed 491.Dq as-is . 492For example: 493.Bd -literal -offset indent 494print/x "eax = " $eax "\enecx = " $ecx "\en" 495.Ed 496.Pp 497will produce: 498.Bd -literal -offset indent 499eax = xxxxxx 500ecx = yyyyyy 501.Ed 502.It Ic ps Ns Oo Cm /a Oc Ns Oo Cm /n Oc Ns Oo Cm /w Oc Ns Oo Cm /l Oc 503A synonym for 504.Ic show all procs . 505.It Ic reboot Op Ar flags 506Reboot, using the optionally supplied boot 507.Ar flags , 508which is a bitmask supporting the same values as for 509.Xr reboot 2 . 510Some of the more useful flags: 511.Bl -column "Value" "RB_POWERDOWN" "Description" 512.It Sy "Value" Ta Sy "Name" Ta Sy "Description" 513.It 0x1 Ta RB_ASKNAME Ta Ask for file name to reboot from 514.It 0x2 Ta RB_SINGLE Ta Reboot to single user mode 515.It 0x4 Ta RB_NOSYNC Ta Don't sync before reboot 516.It 0x8 Ta RB_HALT Ta Halt instead of reboot 517.It 0x40 Ta RB_KDB Ta Boot into kernel debugger 518.It 0x100 Ta RB_DUMP Ta Dump unconditionally before reboot 519.It 0x808 Ta RB_POWERDOWN Ta Power off (or at least halt) 520.El 521.Pp 522Note: Limitations of the command line interface preclude 523specification of a boot string. 524.It Ic search Ns Oo Cm /bhl Oc Ar address Ar value \ 525Oo Ar mask Oc Oo Cm , Ns Ar count Oc 526Search memory from 527.Ar address 528for 529.Ar value . 530The unit size is specified with a modifier character, as per 531.Ic examine . 532Valid modifiers are: 533.Cm /b , 534.Cm /h , 535and 536.Cm /l . 537If no modifier is specified, 538.Cm /l 539is used. 540.Pp 541This command might fail in interesting ways if it doesn't find 542.Ar value . 543This is because 544.Nm 545doesn't always recover from touching bad memory. 546The optional 547.Ar count 548limits the search. 549.It Ic set Cm $ Ns Ar variable Oo Cm = Oc Ar expression 550Set the named variable or register to the value of 551.Ar expression . 552Valid variable names are described in 553.Sx VARIABLES . 554.It Ic show all callout 555Display information about callouts in the system. 556See 557.Xr callout 9 558for more information on callouts. 559.It Ic show all pages 560Display basic information about all physical pages managed by the VM system. 561For more detailed information about a single page, use 562.Ic show page . 563.It Ic show all pools Ns Op Cm /clp 564Display all pool information. 565Modifiers are the same as 566.Ic show pool . 567.It Ic "show\ all\ procs" Ns Oo Cm /a Oc Ns Oo Cm /n Oc Ns Oo Cm /w Oc Ns \ 568Oo Cm /l Oc 569Display all process information. 570Valid modifiers: 571.Bl -tag -width 3n 572.It Cm /n 573show process information in a 574.Xr ps 1 575style format. 576Information printed includes: process ID, parent process ID, 577process group, UID, process status, process flags, number of LWPs, 578command name, and process wait channel message. 579.It Cm /a 580show each process ID, command name, kernel virtual addresses of 581each process' proc structure, u-area, and vmspace structure. 582The vmspace address is also the address of the process' 583vm_map structure, and can be used in the 584.Ic show map 585command. 586.It Cm /w 587show each LWP ID, process ID, command name, system call emulation, 588priority, wait channel message and wait channel address. 589LWPs currently running on a CPU are marked with the '\&>' sign. 590.It Cm /l 591show each LWP ID, process ID, process status, CPU ID the LWP runs on, 592process flags, kernel virtual address of LWP structure, 593LWP name and wait channel message. 594LWPs currently running on a CPU are marked with the '\&>' sign. 595This is the default. 596.El 597.It Ic show routes 598Dump the entire 599.Dv AF_INET 600routing table. 601This command is available only on systems which support inet. 602.It Ic show breaks 603Display all breakpoints. 604.It Ic show buf Ns Oo Cm /f Oc Ar address 605Print the struct buf at 606.Ar address . 607The 608.Cm /f 609does nothing at this time. 610.It Ic show event Ns Oo Cm /f Oc Ns Oo Cm /i Oc Ns Oo Cm /m Oc Ns \ 611Oo Cm /t Oc 612Print all the non-zero 613.Xr evcnt 9 614event counters. 615Valid modifiers: 616.Bl -tag -width 3n 617.It Cm /f 618event counters with a count of zero are printed as well. 619.It Cm /i 620interrupted counters will be displayed. 621.It Cm /m 622misc counters will be displayed. 623.It Cm /t 624trap counters will be displayed. 625.El 626.Pp 627If none of 628.Cm /i , 629.Cm /m 630or 631.Cm /t 632are specified, all are shown. 633You can combine any of these. 634For example, the modifier 635.Cm /itf 636will select both interrupt and trap events, including those that are non-zero. 637.It Ic show files Ar address 638Display information about the vnodes of the files that are currently 639open by the process associated with the proc structure at 640.Ar address . 641This address can be found using the 642.Ic show all procs /a 643command. 644If the kernel is compiled with 645.Cd options LOCKDEBUG 646then details about the locking of the underlying uvm object will also 647be displayed. 648.It Ic show lock Ar address 649Display information about a lock at 650.Ar address . 651This command is useful only if a kernel is compiled with 652.Cd options LOCKDEBUG . 653.It Ic show map Ns Oo Cm /f Oc Ar address 654Print the vm_map at 655.Ar address . 656If 657.Cm /f 658is specified, the complete map is printed. 659.It Ic show mount Ns Oo Cm /f Oc Ar address 660Print the mount structure at 661.Ar address . 662If 663.Cm /f 664is specified, the complete vnode list is printed. 665.It Ic show mbuf Ns Oo Cm /c Oc Ar address 666Print the mbuf structure at 667.Ar address . 668If 669.Cm /c 670is specified, the mbufs in the chain are followed. 671.It Ic show ncache Ar address 672Dump the namecache list associated with vnode at 673.Ar address . 674.It Ic show object Ns Oo Cm /f Oc Ar address 675Print the vm_object at 676.Ar address . 677If 678.Cm /f 679is specified, the complete object is printed. 680.It Ic show page Ns Oo Cm /f Oc Ar address 681Print the vm_page at 682.Ar address . 683If 684.Cm /f 685is specified, the complete page is printed. 686.It Ic show panic 687Print the current "panic" string. 688.It Ic show pool Ns Oo Cm /clp Oc Ar address 689Print the pool at 690.Ar address . 691Valid modifiers: 692.Bl -tag -width 4n -compact 693.It Cm /c 694Print the cachelist and its statistics for this pool. 695.It Cm /l 696Print the log entries for this pool. 697.It Cm /p 698Print the pagelist for this pool. 699.El 700.It Ic show proc Ns Oo Cm /ap Oc Ar address | pid 701Show information about a process and its LWPs. 702LWPs currently running on a CPU are marked with the '\&>' sign. 703.Bl -tag -width 4n -compact 704.It Cm /a 705The argument passed is the kernel virtual address 706of LWP structure. 707.It Cm /p 708The argument passed is a PID. 709Note that 710.Ar pid 711is interpreted using the current radix (see 712.Cm trace/t 713command for details). 714This is the default. 715.El 716.It Ic show registers Ns Op Cm /u 717Display the register set. 718If 719.Cm /u 720is specified, display user registers instead of kernel registers 721or the currently save one. 722.Pp 723Warning: support for 724.Cm /u 725is machine dependent. 726If not supported, incorrect information will be displayed. 727.It Ic show sched_qs 728Print the state of the scheduler's run queues. 729For each run queue that has an LWP, the run queue index and the list 730of LWPs will be shown. 731If the run queue has LWPs, but the sched_whichqs bit is not set for that 732queue, the queue index will be prefixed with a 733.Sq \&! . 734.It Ic show uvmexp 735Print a selection of UVM counters and statistics. 736.It Ic show kernhist Oo Ar addr Oc 737Dumps all the kernel histories if no address is specified, or the history 738at the address. 739This command is available only if a kernel is compiled with one or more 740of the kernel history options 741.Cd KERNHIST , 742.Cd SYSCALL_DEBUG , 743.Cd USB_DEBUG , 744.Cd BIOHIST , 745or 746.Cd UVMHIST . 747.It Ic show vnode Ns Oo Cm /f Oc Ar address 748Print the vnode at 749.Ar address . 750If 751.Cm /f 752is specified, the complete vnode is printed. 753.It Ic show vnode_lock Ns Oo Cm /f Oc Ar address 754Print the vnode which has its lock at 755.Ar address . 756If 757.Cm /f 758is specified, the complete vnode is printed. 759.It Ic show watches 760Display all watchpoints. 761.It Ic sifting Ns Oo Cm /F Oc Ar string 762Search the symbol tables for all symbols of which 763.Ar string 764is a substring, and display them. 765If 766.Cm /F 767is specified, a character is displayed immediately after each symbol 768name indicating the type of symbol. 769.Pp 770For 771.Xr a.out 5 Ns -format 772symbol tables, 773absolute symbols display 774.Sy @ , 775text segment symbols display 776.Sy * , 777data segment symbols display 778.Sy + , 779BSS segment symbols display 780.Sy - , 781and filename symbols display 782.Sy / . 783For ELF-format symbol tables, 784object symbols display 785.Sy + , 786function symbols display 787.Sy * , 788section symbols display 789.Sy & , 790and file symbols display 791.Sy / . 792.Pp 793To sift for a string beginning with a number, escape the first 794character with a backslash as: 795.Bd -literal -offset indent 796sifting \\386 797.Ed 798.It Ic step Ns Oo Cm /p Oc Op Cm , Ns Ar count 799Single-step 800.Ar count 801times. 802If 803.Cm /p 804is specified, print each instruction at each step. 805Otherwise, only print the last instruction. 806.Pp 807Warning: depending on the machine type, it may not be possible 808to single-step through some low-level code paths or user-space 809code. 810On machines with software-emulated single-stepping (e.g., pmax), 811stepping through code executed by interrupt handlers will probably 812do the wrong thing. 813.It Ic sync 814Sync the disks, force a crash dump, and then reboot. 815.It Ic trace Ns Oo Cm /u Ns Oo Cm l Oc Oc Oo Ar frame-address Oc Ns \ 816Oo Cm , Ns Ar count Oc 817Stack trace from 818.Ar frame-address . 819If 820.Cm /u 821is specified, trace user-space, otherwise trace kernel-space. 822.Ar count 823is the number of frames to be traced. 824If 825.Ar count 826is omitted, all frames are printed. 827If 828.Cm /l 829is specified, the trace is printed and also stored in the kernel 830message buffer. 831.Pp 832Warning: user-space stack trace is valid only if the machine dependent 833code supports it. 834.It Ic trace/t Ns Oo Cm l Oc Oo Ar pid Oc Ns Oo Cm , Ns Ar count Oc 835Stack trace by 836.Dq thread 837(process, on 838.Nx ) 839rather than by stack frame address. 840Note that 841.Ar pid 842is interpreted using the current radix, whilst 843.Ic ps 844displays pids in decimal; prefix 845.Ar pid 846with 847.Sq 0t 848to force it to be interpreted as decimal (see 849.Sx VARIABLES 850section for radix). 851If 852.Cm /l 853is specified, the trace is printed and also stored in the kernel 854message buffer. 855.Pp 856Warning: trace by pid is valid only if the machine dependent code 857supports it. 858.It Ic trace/a Ns Oo Cm l Oc Oo Ar lwpaddr Oc Ns Oo Cm , Ns Ar count Oc 859Stack trace by light weight process (LWP) address 860rather than by stack frame address. 861If 862.Cm /l 863is specified, the trace is printed and also stored in the kernel 864message buffer. 865.Pp 866Warning: trace by LWP address is valid only if the machine dependent 867code supports it. 868.It Ic until Ns Op Cm /p 869Stop at the next call or return instruction. 870If 871.Cm /p 872is specified, print the call nesting depth and the 873cumulative instruction count at each call or return. 874Otherwise, only print when the matching return is hit. 875.It Ic watch Ar address Ns Oo Cm , Ns Ar size Oc 876Set a watchpoint for a region. 877Execution stops when an attempt to modify the region occurs. 878.Ar size 879defaults to 4. 880.Pp 881If you specify a wrong space address, the request is 882rejected with an error message. 883.Pp 884Warning: attempts to watch wired kernel memory may cause 885an unrecoverable error in some systems such as i386. 886Watchpoints on user addresses work the best. 887.It Ic whatis Ar address 888Describe what an address is. 889.It Ic write Ns Oo Cm /bhlBHL Oc Ar address Ar expression Oo Ar expression ... Oc 890Write the 891.Ar expression Ns s 892at succeeding locations. 893The unit size is specified with a modifier character, as per 894.Ic examine . 895Valid modifiers are: 896.Cm /b , 897.Cm /h , 898and 899.Cm /l . 900If no modifier is specified, 901.Cm /l 902is used. 903.Pp 904Specifying the modifiers in upper case, 905.Cm /B , 906.Cm /H , 907.Cm /L , 908will prevent 909.Nm 910from reading the memory location first, which is useful for avoiding 911side effects when writing to I/O memory regions. 912.Pp 913Warning: since there is no delimiter between 914.Ar expression Ns s , 915strange things may occur. 916It's best to enclose each 917.Ar expression 918in parentheses. 919.It Ic x Ns Oo Cm / Ns Ar modifier Oc Ar address Ns Op Cm , Ns Ar count 920A synonym for 921.Ic examine . 922.\" XXX - these commands aren't implemented; jhawk 19 May 2000 923.\" .It Ic xf 924.\" Examine forward. 925.\" .Ic xf 926.\" re-executes the most recent 927.\" .Ic execute 928.\" command with the same parameters except that 929.\" .Ar address 930.\" is set to 931.\" .Ar next . 932.\" .It Ic xb 933.\" Examine backward. 934.\" .Ic xb 935.\" re-executes the most recent 936.\" .Ic execute 937.\" command with the same parameters, except that 938.\" .Ar address 939.\" is set to the last start address minus its size. 940.El 941.Sh MACHINE-SPECIFIC COMMANDS 942The "glue" code that hooks 943.Nm 944into the 945.Nx 946kernel for any given port can also add machine specific commands 947to the 948.Nm 949command parser. 950All of these commands are preceded by the command word 951.Em machine 952to indicate that they are part of the machine-specific command 953set (e.g. 954.Ic machine reboot ) . 955Some of these commands are: 956.Ss ACORN26 957.Bl -tag -width "traptrace" -compact 958.It Ic bsw 959Writes one or two bytes to the IObus. 960Takes an address and a value. 961Use the 962.Dq b 963modifier to write a single byte and the 964.Dq h 965modifier to write two bytes. 966.It Ic frame 967Given a trap frame address, print out the trap frame. 968.It Ic irqstat 969Display the IRQ statistics 970.El 971.Ss ALPHA 972.Bl -tag -width "traptrace" -compact 973.It Ic cpu 974Switch to another cpu. 975.\" .It Ic halt 976.\" Call the PROM monitor to halt the CPU. 977.\" .It Ic reboot 978.\" Call the PROM monitor to reboot the CPU. 979.El 980.Ss AMD64 981.Bl -tag -width "traptrace" -compact 982.It Ic cpu 983Switch to another cpu. 984.El 985.Ss ARM32 986.Bl -tag -width "traptrace" -compact 987.It Ic frame 988Given a trap frame address, print out the trap frame. 989.El 990.Ss HPPA 991.Bl -tag -width "traptrace" -compact 992.It Ic frame 993Without an address the default trap frame is printed. 994Otherwise, the trap frame address can be given, or, when the 995.Dq l 996modifier is used, an LWP address. 997.El 998.Ss I386 999.Bl -tag -width "traptrace" -compact 1000.It Ic cpu 1001Switch to another cpu. 1002.El 1003.Ss IA64 1004.Bl -tag -width "traptrace" -compact 1005.It Ic vector 1006Without a vector, information about all 256 vectors is shown. 1007Otherwise, the given vector is shown. 1008.El 1009.Ss MIPS 1010.Bl -tag -width "traptrace" -compact 1011.It Ic cp0 1012Dump CP0 (coprocessor 0) register values. 1013.It Ic kvtop 1014Print the physical address for a given kernel virtual address. 1015.It Ic tlb 1016Print out the Translation Lookaside Buffer (TLB). 1017Only works in 1018.Nx 1019kernels compiled with 1020.Dv DEBUG 1021option. 1022.El 1023.Ss POWERPC 4xx 1024.Bl -tag -width "traptrace" -compact 1025.It Ic ctx 1026Print process MMU context information. 1027.It Ic pv 1028Print PA->VA mapping information. 1029.It Ic reset 1030Reset the system. 1031.It Ic tf 1032Display the contents of the trapframe. 1033.It Ic tlb 1034Display instruction translation storage buffer information. 1035.It Ic dcr 1036Set the DCR register. 1037Must be between 0x00 and 0x3ff. 1038.It Ic user 1039Display user memory. 1040Use the 1041.Dq i 1042modifier to get instruction decoding. 1043.El 1044.Ss POWERPC OEA 1045.Bl -tag -width "traptrace" -compact 1046.It Ic bat 1047Print BAT registers and translations. 1048.It Ic mmu 1049Print MMU registers. 1050.El 1051.Ss SH3 1052.Bl -tag -width "traptrace" -compact 1053.It Ic tlb 1054Print TLB entries. 1055.It Ic cache 1056Print cache entries. 1057.It Ic frame 1058Print switch frame and trap frames. 1059.It Ic stack 1060Print kernel stack usage. 1061Only works in 1062.Nx 1063kernels compiled with the 1064.Dv KSTACK_DEBUG 1065option. 1066.El 1067.Ss SPARC 1068.Bl -tag -width "traptrace" -compact 1069.It Ic cpu 1070Switch to another cpu. 1071.It Ic prom 1072Enter the Sun PROM monitor. 1073.It Ic proc 1074Display some information about the LWP pointed to, or curlwp. 1075.It Ic pcb 1076Display information about the 1077.Dq struct pcb 1078listed. 1079.It Ic page 1080Display the pointer to the 1081.Dq struct vm_page 1082for this physical address. 1083.El 1084.Ss SPARC64 1085.Bl -tag -width "traptrace" -compact 1086.It Ic ctx 1087Print process context information. 1088.It Ic cpu 1089Switch to another cpu. 1090.It Ic dtlb 1091Print data translation look-aside buffer context information. 1092.It Ic dtsb 1093Display data translation storage buffer information. 1094.It Ic kmap 1095Display information about the listed mapping in the kernel pmap. 1096Use the 1097.Dq f 1098modifier to get a full listing. 1099.It Ic extract 1100Extract the physical address for a given virtual address from the kernel pmap. 1101.It Ic fpstate 1102Dump the FPU state. 1103.It Ic itlb 1104Print instruction translation look-aside buffer context information. 1105.It Ic itsb 1106Display instruction translation storage buffer information. 1107.It Ic lwp 1108Display a struct lwp 1109.It Ic pcb 1110Display information about the 1111.Dq struct pcb 1112listed. 1113.It Ic pctx 1114Attempt to change process context. 1115.It Ic page 1116Display the pointer to the 1117.Dq struct vm_page 1118for this physical address. 1119.It Ic phys 1120Display physical memory. 1121.It Ic pmap 1122Display the pmap. 1123Use the 1124.Dq f 1125modifier to get a fuller listing. 1126.It Ic proc 1127Display some information about the process pointed to, or curproc. 1128.It Ic prom 1129Enter the OFW PROM. 1130.It Ic pv 1131Display the 1132.Dq struct pv_entry 1133pointed to. 1134.It Ic sir 1135Reset the machine and enter prom (do a Software Initiated Reset). 1136.It Ic stack 1137Dump the window stack. 1138Use the 1139.Dq u 1140modifier to get userland information. 1141.It Ic tf 1142Display full trap frame state. 1143This is most useful for inclusion with bug reports. 1144.It Ic ts 1145Display trap state. 1146.It Ic traptrace 1147Display or set trap trace information. 1148Use the 1149.Dq r 1150and 1151.Dq f 1152modifiers to get reversed and full information, respectively. 1153.It Ic watch 1154Set or clear a physical or virtual hardware watchpoint. 1155Pass the address to be watched, or 1156.Dq 0 1157(or omit the address) to clear the watchpoint. 1158Optional modifiers are 1159.Dq p 1160for physical address, 1161.Dq r 1162for trap on read access (default: trap on write access only), 1163.Dq b 1164for 8 bit width, 1165.Dq h 1166for 16 bit, 1167.Dq l 1168for 32 bit or 1169.Dq L 1170for 64 bit. 1171.It Ic window 1172Print register window information. 1173Argument is a stack frame number (0 is 1174top of stack, which is used when no index is given). 1175.El 1176.Ss SUN2, SUN3 and SUN3X 1177.Bl -tag -width "traptrace" -compact 1178.It Ic abort 1179Drop into monitor via abort (allows continue). 1180.It Ic halt 1181Exit to Sun PROM monitor as in 1182.Xr halt 8 . 1183.It Ic reboot 1184Reboot the machine as in 1185.Xr reboot 8 . 1186.It Ic pgmap 1187Given an address, print the address, segment map, page map, and 1188Page Table Entry (PTE). 1189.El 1190.Ss VAX 1191.Bl -tag -width "traptrace" -compact 1192.It Ic cpu 1193Switch to another cpu. 1194.El 1195.Sh VARIABLES 1196.Nm 1197accesses registers and variables as 1198.Cm $ Ns Ar name . 1199Register names are as per the 1200.Ic show registers 1201command. 1202Some variables are suffixed with numbers, and may have a modifier 1203following a colon immediately after the variable name. 1204For example, register variables may have a 1205.Sq u 1206modifier to indicate user register 1207(e.g., 1208.Li "$eax:u" ) . 1209.Pp 1210Built-in variables currently supported are: 1211.Bl -tag -offset indent -width "maxwidth" -compact 1212.It Va lines 1213The number of lines. 1214This is used by the 1215.Ic more 1216feature. 1217When this variable is set to zero the 1218.Ic more 1219feature is disabled. 1220.It Va maxoff 1221Addresses are printed as 1222.Li 'symbol'+offset 1223unless 1224.Li offset 1225is greater than 1226.Va maxoff . 1227.It Va maxwidth 1228The width of the displayed line. 1229.Nm 1230wraps the current line by printing new line when 1231.Va maxwidth 1232column is reached. 1233When this variable is set to zero 1234.Nm 1235doesn't perform any wrapping. 1236.It Va onpanic 1237If greater than zero (the default is 1), 1238.Nm 1239will be invoked when the kernel panics. 1240If the kernel configuration option 1241.D1 Cd options DDB_ONPANIC=0 1242is used, 1243.Va onpanic 1244will be initialized to off, causing a stack trace to be printed and 1245the system to be rebooted instead of 1246.Nm 1247being entered. 1248Other useful settings are \-1, which suppresses the stack trace before 1249reboot, and 2, which causes a stack trace to be printed and 1250.Nm 1251to be entered. 1252.It Va fromconsole 1253If non-zero (the default), 1254the kernel allows to enter 1255.Nm 1256from the console (by break signal or special key sequence). 1257If the kernel configuration option 1258.D1 Cd options DDB_FROMCONSOLE=0 1259is used, 1260.Va fromconsole 1261will be initialized to off. 1262.It Va radix 1263Input and output radix. 1264.It Va tabstops 1265Tab stop width. 1266.It Va tee_msgbuf 1267If explicitly set to non zero (zero is the default) all 1268.Nm 1269output will not only be displayed on screen but 1270also be fed to the msgbuf. 1271The default of the variable can be set using the kernel configuration option 1272.D1 Cd options DDB_TEE_MSGBUF=1 1273which will initialize 1274.Va tee_msgbuf 1275to be 1. 1276This option is especially handy for poor souls 1277who don't have a serial console but want to recall 1278.Nm 1279output from a crash investigation. 1280This option is more generic than the /l command modifier possible for 1281selected commands as discussed above to log the output. 1282Mixing both /l 1283and this setting can give double loggings. 1284.It Va panicstackframes 1285Number of stack frames to display on panic. 1286Useful to avoid scrolling away the interesting frames on a glass tty. 1287Default value is 1288.Dv 65535 1289(all frames), useful value around 1290.Dv 10 . 1291.\" .It Va work Ns Sy xx 1292.\" Temporary work variable. 1293.\" .Sq Sy xx 1294.\" is between 0 and 31. 1295.El 1296.Pp 1297All built-in variables are accessible via 1298.Xr sysctl 3 . 1299.Sh EXPRESSIONS 1300Almost all expression operators in C are supported, except 1301.Sq \&~ , 1302.Sq \&^ , 1303and unary 1304.Sq \&& . 1305Special rules in 1306.Nm 1307are: 1308.Bl -tag -offset indent -width "identifier" 1309.It Ar identifier 1310name of a symbol. 1311It is translated to the address (or value) of it. 1312.Sq \&. 1313and 1314.Sq \&: 1315can be used in the identifier. 1316If supported by an object format dependent routine, 1317.Sm off 1318.Xo 1319.Oo Ar filename : Oc 1320.Ar function 1321.Oo : Ar line\ number Oc , 1322.Xc 1323.Sm on 1324.Sm off 1325.Xo 1326.Oo Ar filename : Oc 1327.Ar variable , 1328.Xc 1329.Sm on 1330and 1331.Sm off 1332.Xo 1333.Ar filename 1334.Oo : Ar "line number" Oc , 1335.Xc 1336.Sm on 1337can be accepted as a symbol. 1338The symbol may be prefixed with 1339.Ar symbol_table_name\^ : : 1340(e.g., 1341.Li emulator::mach_msg_trap ) 1342to specify other than kernel symbols. 1343.It Ar number 1344number. 1345Radix is determined by the first two characters: 1346.Sq 0x 1347- hex, 1348.Sq 0o 1349- octal, 1350.Sq 0t 1351- decimal, 1352otherwise follow current radix. 1353.It Cm . 1354.Ar dot 1355.It Cm + 1356.Ar next 1357.It Cm .. 1358address of the start of the last line examined. 1359Unlike 1360.Ar dot 1361or 1362.Ar next , 1363this is only changed by the 1364.Ic examine 1365or 1366.Ic write 1367commands. 1368.It Cm \&" \"" XXX: emacs highlighting 1369last address explicitly specified. 1370.It Cm $ Ns Ar name 1371register name or variable. 1372It is translated to the value of it. 1373It may be followed by a 1374.Sq \&: 1375and modifiers as described above. 1376.It Cm # 1377a binary operator which rounds up the left hand side to the next 1378multiple of right hand side. 1379.It Cm * Ns Ar expr 1380expression indirection. 1381It may be followed by a 1382.Sq \&: 1383and modifiers as described above. 1384.El 1385.Sh SEE ALSO 1386.Xr reboot 2 , 1387.Xr options 4 , 1388.Xr crash 8 , 1389.Xr reboot 8 , 1390.Xr sysctl 8 , 1391.Xr cnmagic 9 1392.Sh HISTORY 1393The 1394.Nm 1395kernel debugger was written as part of the MACH project at 1396Carnegie-Mellon University. 1397