1.\" $NetBSD: ddb.4,v 1.153 2013/01/06 03:35:21 christos 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 5, 2013 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\*[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\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] on PC style keyboards. 124.It "" 125+++++ 126(five plus signs) on PDC console 127.It "" 128\*[Lt]Break\*[Gt] on serial console. 129.It hpcarm 130\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 131.It hpcmips 132\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 133.It hpcsh 134\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 135.It i386 136\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 137.It "" 138\*[Lt]Break\*[Gt] on serial console. 139.It mac68k 140\*[Lt]Command\*[Gt]-\*[Lt]Power\*[Gt], or the Interrupt switch. 141.It macppc 142Some models: 143\*[Lt]Command\*[Gt]-\*[Lt]Option\*[Gt]-\*[Lt]Power\*[Gt] 144.It mvme68k 145Abort switch on CPU card. 146.It pmax 147\*[Lt]Do\*[Gt] on 148.Tn LK-201 149rcons console. 150.It "" 151\*[Lt]Break\*[Gt] on serial console. 152.It sparc 153\*[Lt]L1\*[Gt]-A, or \*[Lt]Stop\*[Gt]-A on a 154.Tn Sun 155keyboard. 156.It "" 157\*[Lt]Break\*[Gt] on serial console. 158.It sparc64 159\*[Lt]L1\*[Gt]-A, or \*[Lt]Stop\*[Gt]-A on a 160.Tn Sun 161keyboard. 162.It "" 163\*[Lt]Break\*[Gt] on serial console. 164.It sun3 165\*[Lt]L1\*[Gt]-A, or \*[Lt]Stop\*[Gt]-A on a 166.Tn Sun 167keyboard. 168.It "" 169\*[Lt]Break\*[Gt] on serial console. 170.It vax 171\*[Lt]Esc\*[Gt]-\*[Lt]Shift\*[Gt]-D on serial console. 172.It x68k 173Interrupt switch on the body. 174.It xen dom0 175\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] on PC style keyboards. 176.It "" 177+++++ 178(five plus signs) on serial console. 179.It xen domU 180+++++ 181(five plus signs) on serial console. 182.It zaurus 183\*[Lt]Ctrl\*[Gt]-\*[Lt]Alt\*[Gt]-\*[Lt]Esc\*[Gt] 184.El 185.Pp 186The key sequence to activate 187.Nm 188can be changed by modifying 189.Dq hw.cnmagic 190with 191.Xr sysctl 8 . 192If the console is not dedicated to 193.Nm 194the sequence should not be easily typed by accident. 195In addition, 196.Nm 197may be explicitly activated by the debugging code in the kernel 198if 199.Cm DDB 200is configured. 201.Pp 202Commands can be automatically run when 203.Nm 204is entered by using 205.Cd options DDB_COMMANDONENTER 206or by setting 207.Ar ddb.commandonenter 208with 209.Xr sysctl 8 . 210Multiple commands can be separated by a semi-colon. 211 212.Sh COMMAND SYNTAX 213The general command syntax is: 214.Bd -ragged -offset indent 215.Ic command Ns Op Cm / Ns Ar modifier 216.Ar address 217.Op Cm , Ns Ar count 218.Ed 219.Pp 220The current memory location being edited is referred to as 221.Ar dot , 222and the next location is 223.Ar next . 224They are displayed as hexadecimal numbers. 225.Pp 226Commands that examine and/or modify memory update 227.Ar dot 228to the address of the last line examined or the last location 229modified, and set 230.Ar next 231to the next location to be examined or modified. 232Other commands don't change 233.Ar dot , 234and set 235.Ar next 236to be the same as 237.Ar dot . 238.Pp 239A blank line repeats the previous command from the address 240.Ar next 241with the previous 242.Cm count 243and no modifiers. 244Specifying 245.Cm address 246sets 247.Em dot 248to the address. 249If 250.Cm address 251is omitted, 252.Em dot 253is used. 254A missing 255.Cm count 256is taken to be 1 for printing commands, and infinity for stack traces. 257.Pp 258The syntax: 259.Bd -ragged -offset indent 260.Cm , Ns Ar count 261.Ed 262.Pp 263repeats the previous command, just as a blank line does, but with 264the specified 265.Cm count . 266.Pp 267.Nm 268has a 269.Xr more 1 Ns -like 270functionality; if a number of lines in a command's output exceeds the number 271defined in the 272.Va lines 273variable, then 274.Nm 275displays 276.Dq "--db more--" 277and waits for a response, which may be one of: 278.Bl -tag -offset indent -width "\*[Lt]return\*[Gt]" 279.It Aq return 280one more line. 281.It Aq space 282one more page. 283.It Ic q 284abort the current command, and return to the command input mode. 285.El 286.Pp 287You can set 288.Va lines 289variable to zero to disable this feature. 290.Pp 291If 292.Nm 293history editing is enabled (by defining the 294.D1 Cd options DDB_HISTORY_SIZE=num 295kernel option), then a history of the last 296.Cm num 297commands is kept. 298The history can be manipulated with the following key sequences: 299.Bl -tag -offset indent -width "\*[Lt]Ctrl\*[Gt]-P" 300.It \*[Lt]Ctrl\*[Gt]-P 301retrieve previous command in history (if any). 302.It \*[Lt]Ctrl\*[Gt]-N 303retrieve next command in history (if any). 304.El 305.Sh COMMANDS 306.Nm 307supports the following commands: 308.Bl -tag -width 5n 309.It Ic \&! Ns Ar address Ns Oo Cm ( Ar expression Ns Oo Ar ,... Oc Ns Cm ) Oc 310A synonym for 311.Ic call . 312.It Ic break Ns Oo Cm /u Oc Ar address Ns Op Cm , Ns Ar count 313Set a breakpoint at 314.Ar address . 315If 316.Ar count 317is supplied, continues 318.Pq Ar count Ns \-1 319times before stopping at the breakpoint. 320If the breakpoint is set, a breakpoint number is printed with 321.Sq \&# . 322This number can be used to 323.Ic delete 324the breakpoint, or to add 325conditions to it. 326.Pp 327If 328.Cm /u 329is specified, 330set a breakpoint at a user-space address. 331Without 332.Cm /u , 333.Ar address 334is considered to be in the kernel-space, and an address in the wrong 335space will be rejected, and an error message will be emitted. 336This modifier may only be used if it is supported by machine dependent 337routines. 338.Pp 339Warning: if a user text is shadowed by a normal user-space debugger, 340user-space breakpoints may not work correctly. 341Setting a breakpoint at the low-level code paths may also cause 342strange behavior. 343.It Ic bt Ns Oo Cm /ul Oc Oo Ar frame-address Oc Ns Oo Cm , Ns Ar count Oc 344A synonym for 345.Ic trace . 346.It Ic bt/t Ns Oo Cm /ul Oc Oo Ar pid Oc Ns Oo Cm , Ns Ar count Oc 347A synonym for 348.Ic trace/t . 349.It Ic bt/a Ns Oo Cm /ul Oc Oo Ar lwpaddr Oc Ns Oo Cm , Ns Ar count Oc 350A synonym for 351.Ic trace/a . 352.It Ic call Ar address Ns Oo Cm ( Ns Ar expression Ns Oo Ar ,... Oc Ns Cm ) Oc 353Call the function specified by 354.Ar address 355with the argument(s) listed in parentheses. 356Parentheses may be omitted if the function takes no arguments. 357The number of arguments is currently limited to 10. 358.It Ic continue Ns Op Cm /c 359Continue execution until a breakpoint or watchpoint. 360If 361.Cm /c 362is specified, count instructions while executing. 363Some machines (e.g., pmax) also count loads and stores. 364.Pp 365Warning: when counting, the debugger is really silently 366single-stepping. 367This means that single-stepping on low-level may cause strange 368behavior. 369.It Ic delete Ar "address" | Cm # Ns Ar number 370Delete a breakpoint. 371The target breakpoint may be specified by 372.Ar address , 373as per 374.Ic break , 375or by the breakpoint number returned by 376.Ic break 377if it's prefixed with 378.Sq Cm \&# . 379.It Ic dmesg Op Ar count 380Prints the contents of the kernel message buffer. 381The optional 382.Ar count 383argument will limit printing to at most the last 384.Ar count 385bytes of the message buffer. 386.It Ic dwatch Ar address 387Delete the watchpoint at 388.Ar address 389that was previously set with 390.Ic watch 391command. 392.It Ic examine Ns Oo Cm / Ns Ar modifier Oc Ar address Ns Op Cm , Ns Ar count 393Display the address locations according to the format in 394.Ar modifier . 395Multiple modifier formats display multiple locations. 396If 397.Ar modifier 398isn't specified, the modifier from the last use of 399.Ic examine 400is used. 401.Pp 402The valid format characters for 403.Ar modifier 404are: 405.Bl -tag -offset indent -width 2n -compact 406.It Cm b 407examine bytes (8 bits). 408.It Cm h 409examine half-words (16 bits). 410.It Cm l 411examine words (legacy 412.Dq long , 41332 bits). 414.It Cm L 415examine long words (implementation dependent) 416.It Cm a 417print the location being examined. 418.It Cm A 419print the location with a line number if possible. 420.It Cm x 421display in unsigned hex. 422.It Cm z 423display in signed hex. 424.It Cm o 425display in unsigned octal. 426.It Cm d 427display in signed decimal. 428.It Cm u 429display in unsigned decimal. 430.It Cm r 431display in current radix, signed. 432.It Cm c 433display low 8 bits as a character. 434Non-printing characters as displayed as an octal escape code 435(e.g., 436.Sq \e000 ) . 437.It Cm s 438display the NUL terminated string at the location. 439Non-printing characters are displayed as octal escapes. 440.It Cm m 441display in unsigned hex with a character dump at the end of each line. 442The location is displayed as hex at the beginning of each line. 443.It Cm i 444display as a machine instruction. 445.It Cm I 446display as a machine instruction, with possible alternative formats 447depending upon the machine: 448.Bl -tag -offset indent -width "sparc" -compact 449.It alpha 450print register operands 451.It m68k 452use Motorola syntax 453.It vax 454don't assume that each external label is a procedure entry mask 455.El 456.El 457.It Ic kill Ar pid Ns Op Cm , Ns Ar signal_number 458Send a signal to the process specified by the 459.Ar pid . 460Note that 461.Ar pid 462is interpreted using the current radix (see 463.Cm trace/t 464command for details). 465If 466.Ar signal_number 467isn't specified, the SIGTERM signal is sent. 468.It Ic match Ns Op Cm /p 469A synonym for 470.Ic next . 471.It Ic next Ns Op Cm /p 472Stop at the matching return instruction. 473If 474.Cm /p 475is specified, print the call nesting depth and the 476cumulative instruction count at each call or return. 477Otherwise, only print when the matching return is hit. 478.It Ic print Ns Oo Cm /axzodurc Oc Ar address Op Ar address ... 479Print addresses 480.Ar address 481according to the modifier character, as per 482.Ic examine . 483Valid modifiers are: 484.Cm /a , 485.Cm /x , 486.Cm /z , 487.Cm /o , 488.Cm /d , 489.Cm /u , 490.Cm /r , 491and 492.Cm /c 493(as per 494.Ic examine ) . 495If no modifier is specified, the most recent one specified is used. 496.Ar address 497may be a string, and is printed 498.Dq as-is . 499For example: 500.Bd -literal -offset indent 501print/x "eax = " $eax "\enecx = " $ecx "\en" 502.Ed 503.Pp 504will produce: 505.Bd -literal -offset indent 506eax = xxxxxx 507ecx = yyyyyy 508.Ed 509.It Ic ps Ns Oo Cm /a Oc Ns Oo Cm /n Oc Ns Oo Cm /w Oc Ns Oo Cm /l Oc 510A synonym for 511.Ic show all procs . 512.It Ic reboot Op Ar flags 513Reboot, using the optionally supplied boot 514.Ar flags , 515which is a bitmask supporting the same values as for 516.Xr reboot 2 . 517Some of the more useful flags: 518.Bl -column "Value" "RB_POWERDOWN" "Description" 519.It Sy "Value" Ta Sy "Name" Ta Sy "Description" 520.It 0x1 Ta RB_ASKNAME Ta Ask for file name to reboot from 521.It 0x2 Ta RB_SINGLE Ta Reboot to single user mode 522.It 0x4 Ta RB_NOSYNC Ta Don't sync before reboot 523.It 0x8 Ta RB_HALT Ta Halt instead of reboot 524.It 0x40 Ta RB_KDB Ta Boot into kernel debugger 525.It 0x100 Ta RB_DUMP Ta Dump unconditionally before reboot 526.It 0x808 Ta RB_POWERDOWN Ta Power off (or at least halt) 527.El 528.Pp 529Note: Limitations of the command line interface preclude 530specification of a boot string. 531.It Ic search Ns Oo Cm /bhl Oc Ar address Ar value \ 532Oo Ar mask Oc Oo Cm , Ns Ar count Oc 533Search memory from 534.Ar address 535for 536.Ar value . 537The unit size is specified with a modifier character, as per 538.Ic examine . 539Valid modifiers are: 540.Cm /b , 541.Cm /h , 542and 543.Cm /l . 544If no modifier is specified, 545.Cm /l 546is used. 547.Pp 548This command might fail in interesting ways if it doesn't find 549.Ar value . 550This is because 551.Nm 552doesn't always recover from touching bad memory. 553The optional 554.Ar count 555limits the search. 556.It Ic set Cm $ Ns Ar variable Oo Cm = Oc Ar expression 557Set the named variable or register to the value of 558.Ar expression . 559Valid variable names are described in 560.Sx VARIABLES . 561.It Ic show all callout 562Display information about callouts in the system. 563See 564.Xr callout 9 565for more information on callouts. 566.It Ic show all pages 567Display basic information about all physical pages managed by the VM system. 568For more detailed information about a single page, use 569.Ic show page . 570.It Ic show all pools Ns Op Cm /clp 571Display all pool information. 572Modifiers are the same as 573.Ic show pool . 574.It Ic "show\ all\ procs" Ns Oo Cm /a Oc Ns Oo Cm /n Oc Ns Oo Cm /w Oc Ns \ 575Oo Cm /l Oc 576Display all process information. 577Valid modifiers: 578.Bl -tag -width 3n 579.It Cm /n 580show process information in a 581.Xr ps 1 582style format. 583Information printed includes: process ID, parent process ID, 584process group, UID, process status, process flags, number of LWPs, 585command name, and process wait channel message. 586.It Cm /a 587show each process ID, command name, kernel virtual addresses of 588each process' proc structure, u-area, and vmspace structure. 589The vmspace address is also the address of the process' 590vm_map structure, and can be used in the 591.Ic show map 592command. 593.It Cm /w 594show each LWP ID, process ID, command name, system call emulation, 595priority, wait channel message and wait channel address. 596LWPs currently running on a CPU are marked with the '\&>' sign. 597.It Cm /l 598show each LWP ID, process ID, process status, CPU ID the LWP runs on, 599process flags, kernel virtual address of LWP structure, 600LWP name and wait channel message. 601LWPs currently running on a CPU are marked with the '\&>' sign. 602This is the default. 603.El 604.It Ic show arptab 605Dump the entire 606.Dv AF_INET 607routing table. 608This command is available only on systems which support inet and ARP. 609.It Ic show breaks 610Display all breakpoints. 611.It Ic show buf Ns Oo Cm /f Oc Ar address 612Print the struct buf at 613.Ar address . 614The 615.Cm /f 616does nothing at this time. 617.It Ic show event Ns Oo Cm /f Oc Ns Oo Cm /i Oc Ns Oo Cm /m Oc Ns \ 618Oo Cm /t Oc 619Print all the non-zero 620.Xr evcnt 9 621event counters. 622Valid modifiers: 623.Bl -tag -width 3n 624.It Cm /f 625event counters with a count of zero are printed as well. 626.It Cm /i 627interrupted counters will be displayed. 628.It Cm /m 629misc counters will be displayed. 630.It Cm /t 631trap counters will be displayed. 632.El 633.Pp 634If none of 635.Cm /i , 636.Cm /m 637or 638.Cm /t 639are specified, all are shown. 640You can combine any of these. 641For example, the modifier 642.Cm /itf 643will select both interrupt and trap events, including those that are non-zero. 644.It Ic show files Ar address 645Display information about the vnodes of the files that are currently 646open by the process associated with the proc structure at 647.Ar address . 648This address can be found using the 649.Ic show all procs /a 650command. 651If the kernel is compiled with 652.Cd options LOCKDEBUG 653then details about the locking of the underlying uvm object will also 654be displayed. 655.It Ic show lock Ar address 656Display information about a lock at 657.Ar address . 658This command is useful only if a kernel is compiled with 659.Cd options LOCKDEBUG . 660.It Ic show malloc Ar address 661If 662.Ar address 663is supplied, display the kernel memory allocator's idea on the 664allocation status for it. 665Also, print out global statistics for the memory allocator. 666This command is useful only if a kernel is compiled with 667.Cd options MALLOC_DEBUG . 668.It Ic show map Ns Oo Cm /f Oc Ar address 669Print the vm_map at 670.Ar address . 671If 672.Cm /f 673is specified, the complete map is printed. 674.It Ic show mount Ns Oo Cm /f Oc Ar address 675Print the mount structure at 676.Ar address . 677If 678.Cm /f 679is specified, the complete vnode list is printed. 680.It Ic show mbuf Ns Oo Cm /c Oc Ar address 681Print the mbuf structure at 682.Ar address . 683If 684.Cm /c 685is specified, the mbufs in the chain are followed. 686.It Ic show ncache Ar address 687Dump the namecache list associated with vnode at 688.Ar address . 689.It Ic show object Ns Oo Cm /f Oc Ar address 690Print the vm_object at 691.Ar address . 692If 693.Cm /f 694is specified, the complete object is printed. 695.It Ic show page Ns Oo Cm /f Oc Ar address 696Print the vm_page at 697.Ar address . 698If 699.Cm /f 700is specified, the complete page is printed. 701.It Ic show panic 702Print the current "panic" string. 703.It Ic show pool Ns Oo Cm /clp Oc Ar address 704Print the pool at 705.Ar address . 706Valid modifiers: 707.Bl -tag -width 4n -compact 708.It Cm /c 709Print the cachelist and its statistics for this pool. 710.It Cm /l 711Print the log entries for this pool. 712.It Cm /p 713Print the pagelist for this pool. 714.El 715.It Ic show proc Ns Oo Cm /ap Oc Ar address | pid 716Show information about a process and its LWPs. 717LWPs currently running on a CPU are marked with the '\&>' sign. 718.Bl -tag -width 4n -compact 719.It Cm /a 720The argument passed is the kernel virtual address 721of LWP structure. 722.It Cm /p 723The argument passed is a PID. 724Note that 725.Ar pid 726is interpreted using the current radix (see 727.Cm trace/t 728command for details). 729This is the default. 730.El 731.It Ic show registers Ns Op Cm /u 732Display the register set. 733If 734.Cm /u 735is specified, display user registers instead of kernel registers 736or the currently save one. 737.Pp 738Warning: support for 739.Cm /u 740is machine dependent. 741If not supported, incorrect information will be displayed. 742.It Ic show sched_qs 743Print the state of the scheduler's run queues. 744For each run queue that has an LWP, the run queue index and the list 745of LWPs will be shown. 746If the run queue has LWPs, but the sched_whichqs bit is not set for that 747queue, the queue index will be prefixed with a 748.Sq \&! . 749.It Ic show uvmexp 750Print a selection of UVM counters and statistics. 751.It Ic show uvmhist 752Dumps the UVM histories. 753This command is available only if a kernel is compiled with 754.Cd options UVMHIST . 755.It Ic show vnode Ns Oo Cm /f Oc Ar address 756Print the vnode at 757.Ar address . 758If 759.Cm /f 760is specified, the complete vnode is printed. 761.It Ic show watches 762Display all watchpoints. 763.It Ic sifting Ns Oo Cm /F Oc Ar string 764Search the symbol tables for all symbols of which 765.Ar string 766is a substring, and display them. 767If 768.Cm /F 769is specified, a character is displayed immediately after each symbol 770name indicating the type of symbol. 771.Pp 772For 773.Xr a.out 5 Ns -format 774symbol tables, 775absolute symbols display 776.Sy @ , 777text segment symbols display 778.Sy * , 779data segment symbols display 780.Sy + , 781.Tn BSS 782segment symbols display 783.Sy - , 784and filename symbols display 785.Sy / . 786For 787.Tn ELF Ns -format 788symbol tables, 789object symbols display 790.Sy + , 791function symbols display 792.Sy * , 793section symbols display 794.Sy \*[Am] , 795and file symbols display 796.Sy / . 797.Pp 798To sift for a string beginning with a number, escape the first 799character with a backslash as: 800.Bd -literal -offset indent 801sifting \\386 802.Ed 803.It Ic step Ns Oo Cm /p Oc Op Cm , Ns Ar count 804Single-step 805.Ar count 806times. 807If 808.Cm /p 809is specified, print each instruction at each step. 810Otherwise, only print the last instruction. 811.Pp 812Warning: depending on the machine type, it may not be possible 813to single-step through some low-level code paths or user-space 814code. 815On machines with software-emulated single-stepping (e.g., pmax), 816stepping through code executed by interrupt handlers will probably 817do the wrong thing. 818.It Ic sync 819Sync the disks, force a crash dump, and then reboot. 820.It Ic trace Ns Oo Cm /u Ns Oo Cm l Oc Oc Oo Ar frame-address Oc Ns \ 821Oo Cm , Ns Ar count Oc 822Stack trace from 823.Ar frame-address . 824If 825.Cm /u 826is specified, trace user-space, otherwise trace kernel-space. 827.Ar count 828is the number of frames to be traced. 829If 830.Ar count 831is omitted, all frames are printed. 832If 833.Cm /l 834is specified, the trace is printed and also stored in the kernel 835message buffer. 836.Pp 837Warning: user-space stack trace is valid only if the machine dependent 838code supports it. 839.It Ic trace/t Ns Oo Cm l Oc Oo Ar pid Oc Ns Oo Cm , Ns Ar count Oc 840Stack trace by 841.Dq thread 842(process, on 843.Nx ) 844rather than by stack frame address. 845Note that 846.Ar pid 847is interpreted using the current radix, whilst 848.Ic ps 849displays pids in decimal; prefix 850.Ar pid 851with 852.Sq 0t 853to force it to be interpreted as decimal (see 854.Sx VARIABLES 855section for radix). 856If 857.Cm /l 858is specified, the trace is printed and also stored in the kernel 859message buffer. 860.Pp 861Warning: trace by pid is valid only if the machine dependent code 862supports it. 863.It Ic trace/a Ns Oo Cm l Oc Oo Ar lwpaddr Oc Ns Oo Cm , Ns Ar count Oc 864Stack trace by light weight process (LWP) address 865rather than by stack frame address. 866If 867.Cm /l 868is specified, the trace is printed and also stored in the kernel 869message buffer. 870.Pp 871Warning: trace by LWP address is valid only if the machine dependent 872code supports it. 873.It Ic until Ns Op Cm /p 874Stop at the next call or return instruction. 875If 876.Cm /p 877is specified, print the call nesting depth and the 878cumulative instruction count at each call or return. 879Otherwise, only print when the matching return is hit. 880.It Ic watch Ar address Ns Oo Cm , Ns Ar size Oc 881Set a watchpoint for a region. 882Execution stops when an attempt to modify the region occurs. 883.Ar size 884defaults to 4. 885.Pp 886If you specify a wrong space address, the request is 887rejected with an error message. 888.Pp 889Warning: attempts to watch wired kernel memory may cause 890an unrecoverable error in some systems such as i386. 891Watchpoints on user addresses work the best. 892.It Ic whatis Ar address 893Describe what an address is. 894.It Ic write Ns Oo Cm /bhlBHL Oc Ar address Ar expression Oo Ar expression ... Oc 895Write the 896.Ar expression Ns s 897at succeeding locations. 898The unit size is specified with a modifier character, as per 899.Ic examine . 900Valid modifiers are: 901.Cm /b , 902.Cm /h , 903and 904.Cm /l . 905If no modifier is specified, 906.Cm /l 907is used. 908.Pp 909Specifying the modifiers in upper case, 910.Cm /B , 911.Cm /H , 912.Cm /L , 913will prevent 914.Nm 915from reading the memory location first, which is useful for avoiding 916side effects when writing to I/O memory regions. 917.Pp 918Warning: since there is no delimiter between 919.Ar expression Ns s , 920strange things may occur. 921It's best to enclose each 922.Ar expression 923in parentheses. 924.It Ic x Ns Oo Cm / Ns Ar modifier Oc Ar address Ns Op Cm , Ns Ar count 925A synonym for 926.Ic examine . 927.\" XXX - these commands aren't implemented; jhawk 19 May 2000 928.\" .It Ic xf 929.\" Examine forward. 930.\" .Ic xf 931.\" re-executes the most recent 932.\" .Ic execute 933.\" command with the same parameters except that 934.\" .Ar address 935.\" is set to 936.\" .Ar next . 937.\" .It Ic xb 938.\" Examine backward. 939.\" .Ic xb 940.\" re-executes the most recent 941.\" .Ic execute 942.\" command with the same parameters, except that 943.\" .Ar address 944.\" is set to the last start address minus its size. 945.El 946.Sh MACHINE-SPECIFIC COMMANDS 947The "glue" code that hooks 948.Nm 949into the 950.Nx 951kernel for any given port can also add machine specific commands 952to the 953.Nm 954command parser. 955All of these commands are preceded by the command word 956.Em machine 957to indicate that they are part of the machine-specific command 958set (e.g. 959.Ic machine reboot ) . 960Some of these commands are: 961.Ss ACORN26 962.Bl -tag -width "traptrace" -compact 963.It Ic bsw 964Writes one or two bytes to the IObus. 965Takes an address and a value. 966Use the 967.Dq b 968modifier to write a single byte and the 969.Dq h 970modifier to write two bytes. 971.It Ic frame 972Given a trap frame address, print out the trap frame. 973.It Ic irqstat 974Display the IRQ statistics 975.El 976.Ss ALPHA 977.Bl -tag -width "traptrace" -compact 978.It Ic cpu 979Switch to another cpu. 980.\" .It Ic halt 981.\" Call the PROM monitor to halt the CPU. 982.\" .It Ic reboot 983.\" Call the PROM monitor to reboot the CPU. 984.El 985.Ss AMD64 986.Bl -tag -width "traptrace" -compact 987.It Ic cpu 988Switch to another cpu. 989.El 990.Ss ARM32 991.Bl -tag -width "traptrace" -compact 992.It Ic frame 993Given a trap frame address, print out the trap frame. 994.El 995.Ss HP700 996.Bl -tag -width "traptrace" -compact 997.It Ic frame 998Without an address the default trap frame is printed. 999Otherwise, the trap frame address can be given, or, when the 1000.Dq l 1001modifier is used, an LWP address. 1002.El 1003.Ss I386 1004.Bl -tag -width "traptrace" -compact 1005.It Ic cpu 1006Switch to another cpu. 1007.El 1008.Ss IA64 1009.Bl -tag -width "traptrace" -compact 1010.It Ic vector 1011Without a vector, information about all 256 vectors is shown. 1012Otherwise, the given vector is shown. 1013.El 1014.Ss MIPS 1015.Bl -tag -width "traptrace" -compact 1016.It Ic cp0 1017Dump CP0 (coprocessor 0) register values. 1018.It Ic kvtop 1019Print the physical address for a given kernel virtual address. 1020.It Ic tlb 1021Print out the Translation Lookaside Buffer (TLB). 1022Only works in 1023.Nx 1024kernels compiled with 1025.Dv DEBUG 1026option. 1027.El 1028.Ss POWERPC 4xx 1029.Bl -tag -width "traptrace" -compact 1030.It Ic ctx 1031Print process MMU context information. 1032.It Ic pv 1033Print PA-\*[Gt]VA mapping information. 1034.It Ic reset 1035Reset the system. 1036.It Ic tf 1037Display the contents of the trapframe. 1038.It Ic tlb 1039Display instruction translation storage buffer information. 1040.It Ic dcr 1041Set the DCR register. 1042Must be between 0x00 and 0x3ff. 1043.It Ic user 1044Display user memory. 1045Use the 1046.Dq i 1047modifier to get instruction decoding. 1048.El 1049.Ss POWERPC OEA 1050.Bl -tag -width "traptrace" -compact 1051.It Ic bat 1052Print BAT registers and translations. 1053.It Ic mmu 1054Print MMU registers. 1055.El 1056.Ss SH3 1057.Bl -tag -width "traptrace" -compact 1058.It Ic tlb 1059Print TLB entries. 1060.It Ic cache 1061Print cache entries. 1062.It Ic frame 1063Print switch frame and trap frames. 1064.It Ic stack 1065Print kernel stack usage. 1066Only works in 1067.Nx 1068kernels compiled with the 1069.Dv KSTACK_DEBUG 1070option. 1071.El 1072.Ss SPARC 1073.Bl -tag -width "traptrace" -compact 1074.It Ic cpu 1075Switch to another cpu. 1076.It Ic prom 1077Enter the Sun PROM monitor. 1078.It Ic proc 1079Display some information about the LWP pointed to, or curlwp. 1080.It Ic pcb 1081Display information about the 1082.Dq struct pcb 1083listed. 1084.It Ic page 1085Display the pointer to the 1086.Dq struct vm_page 1087for this physical address. 1088.El 1089.Ss SPARC64 1090.Bl -tag -width "traptrace" -compact 1091.It Ic ctx 1092Print process context information. 1093.It Ic cpu 1094Switch to another cpu. 1095.It Ic dtlb 1096Print data translation look-aside buffer context information. 1097.It Ic dtsb 1098Display data translation storage buffer information. 1099.It Ic kmap 1100Display information about the listed mapping in the kernel pmap. 1101Use the 1102.Dq f 1103modifier to get a full listing. 1104.It Ic extract 1105Extract the physical address for a given virtual address from the kernel pmap. 1106.It Ic fpstate 1107Dump the FPU state. 1108.It Ic itlb 1109Print instruction translation look-aside buffer context information. 1110.It Ic itsb 1111Display instruction translation storage buffer information. 1112.It Ic lwp 1113Display a struct lwp 1114.It Ic pcb 1115Display information about the 1116.Dq struct pcb 1117listed. 1118.It Ic pctx 1119Attempt to change process context. 1120.It Ic page 1121Display the pointer to the 1122.Dq struct vm_page 1123for this physical address. 1124.It Ic phys 1125Display physical memory. 1126.It Ic pmap 1127Display the pmap. 1128Use the 1129.Dq f 1130modifier to get a fuller listing. 1131.It Ic proc 1132Display some information about the process pointed to, or curproc. 1133.It Ic prom 1134Enter the OFW PROM. 1135.It Ic pv 1136Display the 1137.Dq struct pv_entry 1138pointed to. 1139.It Ic sir 1140Reset the machine and enter prom (do a Software Initiated Reset). 1141.It Ic stack 1142Dump the window stack. 1143Use the 1144.Dq u 1145modifier to get userland information. 1146.It Ic tf 1147Display full trap frame state. 1148This is most useful for inclusion with bug reports. 1149.It Ic ts 1150Display trap state. 1151.It Ic traptrace 1152Display or set trap trace information. 1153Use the 1154.Dq r 1155and 1156.Dq f 1157modifiers to get reversed and full information, respectively. 1158.It Ic watch 1159Set or clear a physical or virtual hardware watchpoint. 1160Pass the address to be watched, or 1161.Dq 0 1162(or omit the address) to clear the watchpoint. 1163Optional modifiers are 1164.Dq p 1165for physical address, 1166.Dq r 1167for trap on read access (default: trap on write access only), 1168.Dq b 1169for 8 bit width, 1170.Dq h 1171for 16 bit, 1172.Dq l 1173for 32 bit or 1174.Dq L 1175for 64 bit. 1176.It Ic window 1177Print register window information. 1178Argument is a stack frame number (0 is 1179top of stack, which is used when no index is given). 1180.El 1181.Ss SUN2, SUN3 and SUN3X 1182.Bl -tag -width "traptrace" -compact 1183.It Ic abort 1184Drop into monitor via abort (allows continue). 1185.It Ic halt 1186Exit to Sun PROM monitor as in 1187.Xr halt 8 . 1188.It Ic reboot 1189Reboot the machine as in 1190.Xr reboot 8 . 1191.It Ic pgmap 1192Given an address, print the address, segment map, page map, and 1193Page Table Entry (PTE). 1194.El 1195.Ss VAX 1196.Bl -tag -width "traptrace" -compact 1197.It Ic cpu 1198Switch to another cpu. 1199.El 1200.Sh VARIABLES 1201.Nm 1202accesses registers and variables as 1203.Cm $ Ns Ar name . 1204Register names are as per the 1205.Ic show registers 1206command. 1207Some variables are suffixed with numbers, and may have a modifier 1208following a colon immediately after the variable name. 1209For example, register variables may have a 1210.Sq u 1211modifier to indicate user register 1212(e.g., 1213.Li "$eax:u" ) . 1214.Pp 1215Built-in variables currently supported are: 1216.Bl -tag -offset indent -width "maxwidth" -compact 1217.It Va lines 1218The number of lines. 1219This is used by the 1220.Ic more 1221feature. 1222When this variable is set to zero the 1223.Ic more 1224feature is disabled. 1225.It Va maxoff 1226Addresses are printed as 1227.Li 'symbol'+offset 1228unless 1229.Li offset 1230is greater than 1231.Va maxoff . 1232.It Va maxwidth 1233The width of the displayed line. 1234.Nm 1235wraps the current line by printing new line when 1236.Va maxwidth 1237column is reached. 1238When this variable is set to zero 1239.Nm 1240doesn't perform any wrapping. 1241.It Va onpanic 1242If greater than zero (the default is 1), 1243.Nm 1244will be invoked when the kernel panics. 1245If the kernel configuration option 1246.D1 Cd options DDB_ONPANIC=0 1247is used, 1248.Va onpanic 1249will be initialized to off, causing a stack trace to be printed and 1250the system to be rebooted instead of 1251.Nm 1252being entered. 1253Other useful settings are \-1, which suppresses the stack trace before 1254reboot, and 2, which causes a stack trace to be printed and 1255.Nm 1256to be entered. 1257.It Va fromconsole 1258If non-zero (the default), 1259the kernel allows to enter 1260.Nm 1261from the console (by break signal or special key sequence). 1262If the kernel configuration option 1263.D1 Cd options DDB_FROMCONSOLE=0 1264is used, 1265.Va fromconsole 1266will be initialized to off. 1267.It Va radix 1268Input and output radix. 1269.It Va tabstops 1270Tab stop width. 1271.It Va tee_msgbuf 1272If explicitly set to non zero (zero is the default) all 1273.Nm 1274output will not only be displayed on screen but 1275also be fed to the msgbuf. 1276The default of the variable can be set using the kernel configuration option 1277.D1 Cd options DDB_TEE_MSGBUF=1 1278which will initialize 1279.Va tee_msgbuf 1280to be 1. 1281This option is especially handy for poor souls 1282who don't have a serial console but want to recall 1283.Nm 1284output from a crash investigation. 1285This option is more generic than the /l command modifier possible for 1286selected commands as discussed above to log the output. 1287Mixing both /l 1288and this setting can give double loggings. 1289.\" .It Va work Ns Sy xx 1290.\" Temporary work variable. 1291.\" .Sq Sy xx 1292.\" is between 0 and 31. 1293.El 1294.Pp 1295All built-in variables are accessible via 1296.Xr sysctl 3 . 1297.Sh EXPRESSIONS 1298Almost all expression operators in C are supported, except 1299.Sq \&~ , 1300.Sq \&^ , 1301and unary 1302.Sq \&\*[Am] . 1303Special rules in 1304.Nm 1305are: 1306.Bl -tag -offset indent -width "identifier" 1307.It Ar identifier 1308name of a symbol. 1309It is translated to the address (or value) of it. 1310.Sq \&. 1311and 1312.Sq \&: 1313can be used in the identifier. 1314If supported by an object format dependent routine, 1315.Sm off 1316.Xo 1317.Oo Ar filename : Oc 1318.Ar function 1319.Oo : Ar line\ number Oc , 1320.Xc 1321.Sm on 1322.Sm off 1323.Xo 1324.Oo Ar filename : Oc 1325.Ar variable , 1326.Xc 1327.Sm on 1328and 1329.Sm off 1330.Xo 1331.Ar filename 1332.Oo : Ar "line number" Oc , 1333.Xc 1334.Sm on 1335can be accepted as a symbol. 1336The symbol may be prefixed with 1337.Ar symbol_table_name\^ : : 1338(e.g., 1339.Li emulator::mach_msg_trap ) 1340to specify other than kernel symbols. 1341.It Ar number 1342number. 1343Radix is determined by the first two characters: 1344.Sq 0x 1345- hex, 1346.Sq 0o 1347- octal, 1348.Sq 0t 1349- decimal, 1350otherwise follow current radix. 1351.It Cm . 1352.Ar dot 1353.It Cm + 1354.Ar next 1355.It Cm .. 1356address of the start of the last line examined. 1357Unlike 1358.Ar dot 1359or 1360.Ar next , 1361this is only changed by the 1362.Ic examine 1363or 1364.Ic write 1365commands. 1366.It Cm \&" \"" XXX: emacs highlighting 1367last address explicitly specified. 1368.It Cm $ Ns Ar name 1369register name or variable. 1370It is translated to the value of it. 1371It may be followed by a 1372.Sq \&: 1373and modifiers as described above. 1374.It Cm # 1375a binary operator which rounds up the left hand side to the next 1376multiple of right hand side. 1377.It Cm * Ns Ar expr 1378expression indirection. 1379It may be followed by a 1380.Sq \&: 1381and modifiers as described above. 1382.El 1383.Sh SEE ALSO 1384.Xr reboot 2 , 1385.Xr options 4 , 1386.Xr crash 8 , 1387.Xr reboot 8 , 1388.Xr sysctl 8 , 1389.Xr cnmagic 9 1390.Sh HISTORY 1391The 1392.Nm 1393kernel debugger was written as part of the MACH project at 1394Carnegie-Mellon University. 1395