867 lines
19 KiB
Groff
867 lines
19 KiB
Groff
.\" $NetBSD: ddb.4,v 1.26 1998/05/26 05:09:10 msaitoh Exp $
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.\"
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.\" Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Luke Mewburn
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" ---
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.\" This manual page was derived from a -man.old document which bore
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.\" the following copyright message:
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.\" ---
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.\"
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.\" Mach Operating System
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.\" Copyright (c) 1991,1990 Carnegie Mellon University
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.\" All Rights Reserved.
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.\"
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.\" Permission to use, copy, modify and distribute this software and its
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.\" documentation is hereby granted, provided that both the copyright
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.\" notice and this permission notice appear in all copies of the
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.\" software, derivative works or modified versions, and any portions
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.\" thereof, and that both notices appear in supporting documentation.
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.\"
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.\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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.\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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.\" ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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.\"
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.\" Carnegie Mellon requests users of this software to return to
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.\"
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.\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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.\" School of Computer Science
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.\" Carnegie Mellon University
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.\" Pittsburgh PA 15213-3890
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.\"
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.\" any improvements or extensions that they make and grant Carnegie Mellon
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.\" the rights to redistribute these changes.
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.\"
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.Dd November 17, 1997
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.Dt DDB 4
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.Os NetBSD
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.Sh NAME
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.Nm ddb
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.Nd in-kernel debugger
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|
.Sh SYNOPSIS
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.Cd options DDB
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.Pp
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|
To enable history editing:
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.Cd options DDB_HISTORY_SIZE=integer
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.Pp
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|
To disable entering
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.Nm
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|
upon kernel panic:
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|
.Cd options DDB_ONPANIC=0
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|
.Sh DESCRIPTION
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|
.Nm
|
|
is the in-kernel debugger.
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It may be entered at any time via a special key sequence, and
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optionally may be invoked when the kernel panics.
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|
.Sh ENTERING THE DEBUGGER
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|
Unless
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.Dv DDB_ONPANIC
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is set to 0,
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.Nm
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will be activated whenever the kernel would otherwise panic.
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.Pp
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|
.Nm
|
|
may also be activated from the console.
|
|
In general, sending a break on a serial console will activate
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|
.Nm "" .
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|
There are also key sequences for each port that will activate
|
|
.Nm
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|
from the keyboard:
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|
.Bl -tag -offset indent -width "mvme68k"
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|
.It alpha
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|
<Ctrl>-<Alt>-<Esc> on PC style keyboards.
|
|
.It amiga
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|
<LAlt>-<LAmiga>-<F10>
|
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.It hp300
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<Shift>-<Reset>
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|
.It i386
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<Ctrl>-<Alt>-<Esc>
|
|
.It mac68k
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<Command>-<Power>, or the Interrupt switch.
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|
.It mvme68k
|
|
Abort switch on CPU card.
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.It pmax
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<Do> on
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.Tn LK-201
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rcons console.
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.br
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<Break> on serial console.
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.It sparc
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<L1>-A, or <Stop>-A on a
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.Tn Sun
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keyboard.
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.br
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<Break> on serial console.
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.It sun3
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<L1>-A, or <Stop>-A on a
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.Tn Sun
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keyboard.
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.br
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<Break> on serial console.
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.It sun3x
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<L1>-A, or <Stop>-A on a
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.Tn Sun
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keyboard.
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.br
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<Break> on serial console.
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.It x68k
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Interrupt switch on the body.
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|
.El
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.Pp
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|
In addition,
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|
.Nm
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|
may be explicitly activated by the debugging code in the kernel
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|
if
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.Cm DDB
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is configured.
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|
.Sh COMMAND SYNTAX
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.Pp
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|
The general command syntax is:
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.Bd -ragged -offset indent
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|
.Ic command Ns Op Cm / Ns Ar modifier
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.Ar address
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.Op Cm , Ns Ar count
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.Ed
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.Pp
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|
The current memory location being edited is referred to as
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.Ar dot ,
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|
and the next location is
|
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.Ar next .
|
|
They are displayed as hexadecimal numbers.
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|
.Pp
|
|
Commands that examine and/or modify memory update
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.Ar dot
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|
to the address of the last line examined or the last location
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modified, and set
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|
.Ar next
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|
to the next location to be examined or modified.
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Other commands don't change
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.Ar dot ,
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and set
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.Ar next
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to be the same as
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|
.Ar dot .
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.Pp
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|
A blank line repeats the previous command from the address
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.Ar next
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with a
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.Cm count
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of 1 and no modifiers.
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Specifying
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.Cm address
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sets
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.Em dot
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to the address.
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If
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.Cm address
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is omitted,
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|
.Em dot
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is used.
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|
A missing
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.Cm count
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is taken to be 1 for printing commands, and infinity for stack traces.
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.Pp
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.Nm
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has a
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.Xr more 1 -like
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functionality; if a number of lines in a command's output exceeds the number
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defined in the
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.Va lines
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variable, then
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.Nm
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|
displays
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.Dq "--db more--"
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|
and waits for a response, which may be one of:
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|
.Bl -tag -offset indent -width "<return>"
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.It <return>
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one more line.
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|
.It <space>
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one more page.
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.It Ic q
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abort the current command, and return to the command input mode.
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.El
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.Pp
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|
If
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.Nm
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history editing is enabled (by defining the
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|
.D1 Cd options DDB_HISTORY_SIZE=num
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kernel option), then a history of the last
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.Cm num
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commands is kept.
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|
The history can be manipulated with the following key sequences:
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|
.Bl -tag -offset indent -width "<Ctrl>-P"
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|
.It <Ctrl>-P
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|
retrieve previous command in history (if any).
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|
.It <Ctrl>-N
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|
retrieve next command in history (if any).
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.El
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|
.Sh COMMANDS
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.Nm
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|
supports the following commands:
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|
.Bl -tag -width 5n
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|
.It Xo
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|
.Ic examine Ns Op Cm / Ns Ar modifier
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|
.Ar address Ns Op Cm , Ns Ar count
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|
.Xc
|
|
Display the address locations according to the format in
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|
.Ar modifier .
|
|
Multiple modifier formats display multiple locations.
|
|
If
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|
.Ar modifier
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|
isn't specified, the modifier from the last use of
|
|
.Ic examine
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|
is used.
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|
.Pp
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|
The valid format characters for
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.Ar modifier
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|
are:
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|
.Bl -tag -offset indent -width 2n
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.It Cm b
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|
examine bytes (8 bits).
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|
.It Cm h
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|
examine half-words (16 bits).
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|
.It Cm l
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|
examine long-words (32 bits).
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|
.It Cm a
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|
print the location being examined.
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|
.It Cm A
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|
print the location with a line number if possible.
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|
.It Cm x
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|
display in unsigned hex.
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|
.It Cm z
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|
display in signed hex.
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|
.It Cm o
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|
display in unsigned octal.
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|
.It Cm d
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|
display in signed decimal.
|
|
.It Cm u
|
|
display in unsigned decimal.
|
|
.It Cm r
|
|
display in current radix, signed.
|
|
.It Cm c
|
|
display low 8 bits as a character.
|
|
Non-printing characters as displayed as an octal escape code
|
|
(e.g.,
|
|
.Sq \e000 ) .
|
|
.It Cm s
|
|
display the NUL terminated string at the location.
|
|
Non-printing characters are displayed as octal escapes.
|
|
.It Cm m
|
|
display in unsigned hex with a character dump at the end of each line.
|
|
The location is displayed as hex at the beginning of each line.
|
|
.It Cm i
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|
display as a machine instruction.
|
|
.It Cm I
|
|
display as a machine instruction, with possible alternative formats
|
|
depending upon the machine:
|
|
.Bl -tag -offset indent -width "sparc"
|
|
.It alpha
|
|
print register operands
|
|
.It m68k
|
|
use Motorola syntax
|
|
.It pc532
|
|
print instruction bytes in hex
|
|
.It vax
|
|
don't assume that each external label is a procedure entry mask
|
|
.El
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|
.El
|
|
.It Xo
|
|
.Ic x Ns Op Cm / Ns Ar modifier
|
|
.Ar address Ns Op Cm , Ns Ar count
|
|
.Xc
|
|
A synonym for
|
|
.Ic examine .
|
|
.It Ic xf
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|
Examine forward.
|
|
.Ic xf
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|
re-executes the most recent
|
|
.Ic execute
|
|
command with the same parameters except that
|
|
.Ar address
|
|
is set to
|
|
.Ar next .
|
|
.It Ic xb
|
|
Examine backward.
|
|
.Ic xb
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|
re-executes the most recent
|
|
.Ic execute
|
|
command with the same parameters, except that
|
|
.Ar address
|
|
is set to the last start address minus its size.
|
|
.It Xo
|
|
.Ic print Ns Op Cm /axzodurc
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|
.Ar address Op Ar address ...
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|
.Xc
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|
Print addresses
|
|
.Ar address
|
|
according to the modifier character, as per
|
|
.Ic examine .
|
|
Valid modifiers are:
|
|
.Cm /a ,
|
|
.Cm /x ,
|
|
.Cm /z ,
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|
.Cm /o ,
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|
.Cm /d ,
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|
.Cm /u ,
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|
.Cm /r ,
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|
and
|
|
.Cm /c
|
|
(as per
|
|
.Ic examine ) .
|
|
If no modifier is specified, the most recent one specified is used.
|
|
.Ar address
|
|
may be a string, and is printed
|
|
.Dq as-is .
|
|
For example:
|
|
.Bd -literal -offset indent
|
|
print/x "eax = " $eax "\enecx = " $ecx "\en"
|
|
.Ed
|
|
.Pp
|
|
will produce:
|
|
.Bd -literal -offset indent
|
|
eax = xxxxxx
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|
ecx = yyyyyy
|
|
.Ed
|
|
.It Xo
|
|
.Ic write Ns Op Cm /bhl
|
|
.Ar address
|
|
.Ar expression Op Ar expression ...
|
|
.Xc
|
|
Write the
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|
.Ar expression Ns s
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|
at succeeding locations.
|
|
The unit size is specified with a modifier character, as per
|
|
.Ic examine .
|
|
Valid modifiers are:
|
|
.Cm /b ,
|
|
.Cm /h ,
|
|
and
|
|
.Cm /l .
|
|
If no modifier is specified,
|
|
.Cm /l
|
|
is used.
|
|
.Pp
|
|
Warning: since there is no delimiter between
|
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.Ar expression Ns s ,
|
|
strange things may occur.
|
|
It's best to enclose each
|
|
.Ar expression
|
|
in parentheses.
|
|
.It Xo
|
|
.Ic set
|
|
.Cm $ Ns Ar variable
|
|
.Op Cm =
|
|
.Ar expression
|
|
.Xc
|
|
Set the named variable or register to the value of
|
|
.Ar expression .
|
|
Valid variable names are described in
|
|
.Sx VARIABLES .
|
|
.It Xo
|
|
.Cm break Ns Op Cm /u
|
|
.Ar address Ns Op Cm , Ns Ar count
|
|
.Xc
|
|
Set a breakpoint at
|
|
.Ar address .
|
|
If
|
|
.Ar count
|
|
is supplied, continues
|
|
.Pq Ar count Ns -1
|
|
times before stopping at the breakpoint.
|
|
If the breakpoint is set, a breakpoint number is printed with
|
|
.Sq # .
|
|
This number can be used to
|
|
.Ic delete
|
|
the breakpoint, or to add
|
|
conditions to it.
|
|
.Pp
|
|
If
|
|
.Cm /u
|
|
is specified,
|
|
set a breakpoint at a user-space address.
|
|
Without
|
|
.Cm /u ,
|
|
.Ar address
|
|
is considered to be in the kernel-space, and an address in the wrong
|
|
space will be rejected, and an error message will be emitted.
|
|
This modifier may only be used if it is supported by machine dependent
|
|
routines.
|
|
.Pp
|
|
Warning: if a user text is shadowed by a normal user-space debugger,
|
|
user-space breakpoints may not work correctly.
|
|
Setting a breakpoint at the low-level code paths may also cause
|
|
strange behavior.
|
|
.It Xo
|
|
.Ic delete
|
|
.Ar "address" |
|
|
.Cm # Ns Ar number
|
|
.Xc
|
|
Delete a breakpoint.
|
|
The target breakpoint may be specified by
|
|
.Ar address ,
|
|
as per
|
|
.Ic break ,
|
|
or by the breakpoint number returned by
|
|
.Ic break
|
|
if it's prefixed with
|
|
.Sq Cm # .
|
|
.It Xo
|
|
.Ic step Ns Op Cm /p
|
|
.Op Cm , Ns Ar count
|
|
.Xc
|
|
Single-step
|
|
.Ar count
|
|
times.
|
|
If
|
|
.Cm /p
|
|
is specified, print each instruction at each step.
|
|
Otherwise, only print the last instruction.
|
|
.Pp
|
|
Warning: depending on the machine type, it may not be possible
|
|
to single-step through some low-level code paths or user-space
|
|
code.
|
|
On machines with software-emulated single-stepping (e.g., pmax),
|
|
stepping through code executed by interrupt handlers will probably
|
|
do the wrong thing.
|
|
.It Ic continue Ns Op Cm /c
|
|
Continue execution until a breakpoint or watchpoint.
|
|
If
|
|
.Cm /c
|
|
is specified, count instructions while executing.
|
|
Some machines (e.g., pmax) also count loads and stores.
|
|
.Pp
|
|
Warning: when counting, the debugger is really silently
|
|
single-stepping.
|
|
This means that single-stepping on low-level may cause strange
|
|
behavior.
|
|
.It Ic until Ns Op Cm /p
|
|
Stop at the next call or return instruction.
|
|
If
|
|
.Cm /p
|
|
is specified, print the call nesting depth and the
|
|
cumulative instruction count at each call or return.
|
|
Otherwise, only print when the matching return is hit.
|
|
.It Ic next Ns Op Cm /p
|
|
Stop at the matching return instruction.
|
|
If
|
|
.Cm /p
|
|
is specified, print the call nesting depth and the
|
|
cumulative instruction count at each call or return.
|
|
Otherwise, only print when the matching return is hit.
|
|
.It Ic match Ns Op Cm /p
|
|
A synonym for
|
|
.Ic next .
|
|
.It Xo
|
|
.Cm trace Ns Op Cm /u
|
|
.Sm off
|
|
.Op Ar frame-address
|
|
.Op Cm , Ar count
|
|
.Sm on
|
|
.Xc
|
|
Stack trace from
|
|
.Ar frame-address .
|
|
If
|
|
.Cm /u
|
|
is specified, trace user-space, otherwise trace kernel-space.
|
|
.Ar count
|
|
is the number of frames to be traced.
|
|
If
|
|
.Ar count
|
|
is omitted, all frames are printed.
|
|
.Pp
|
|
Warning: user-space stack trace is valid only if the machine dependent
|
|
code supports it.
|
|
.It Xo
|
|
.Cm trace/t
|
|
.Sm off
|
|
.Op Ar pid
|
|
.Op Cm , Ar count
|
|
.Sm on
|
|
.Xc
|
|
Stack trace by
|
|
.Dq thread
|
|
(process, on
|
|
.Nx )
|
|
rather than by stack frame address.
|
|
Note that
|
|
.Ar pid
|
|
is interpreted using the current radix, whilst
|
|
.Ic ps
|
|
displays pids in decimal; prefix
|
|
.Ar pid
|
|
with
|
|
.Sq 0t
|
|
to force it to be interpreted as decimal.
|
|
.Pp
|
|
Warning: trace by pid is valid only if the machine dependent code
|
|
supports it.
|
|
.It Xo
|
|
.Ic search Ns Op Cm /bhl
|
|
.Ar address
|
|
.Ar value
|
|
.Op Ar mask
|
|
.Op Cm , Ns Ar count
|
|
.Xc
|
|
Search memory from
|
|
.Ar address
|
|
for
|
|
.Ar value .
|
|
The unit size is specified with a modifier character, as per
|
|
.Ic examine .
|
|
Valid modifiers are:
|
|
.Cm /b ,
|
|
.Cm /h ,
|
|
and
|
|
.Cm /l .
|
|
If no modifier is specified,
|
|
.Cm /l
|
|
is used.
|
|
.Pp
|
|
This command might fail in interesting ways if it doesn't find
|
|
.Ar value .
|
|
This is because
|
|
.Nm
|
|
doesn't always recover from touching bad memory.
|
|
The optional
|
|
.Ar count
|
|
limits the search.
|
|
.It Ic reboot Op Ar flags
|
|
Reboot, using the optionally supplied boot
|
|
.Ar flags .
|
|
.Pp
|
|
Note: Limitations of the command line interface preclude
|
|
specification of a boot string.
|
|
.It Xo
|
|
.Sm off
|
|
.Ic "show\ all\ procs"
|
|
.Op Cm /a
|
|
.Op Cm /n
|
|
.Op Cm /w
|
|
.Sm on
|
|
.Xc
|
|
Display all process information.
|
|
Valid modifiers:
|
|
.Bl -tag -width 3n
|
|
.It Cm /n
|
|
show process information in a
|
|
.Xr ps 1
|
|
style format (this is the default).
|
|
Information printed includes: process ID, parent process ID,
|
|
process group, UID, process status, process flags, process
|
|
command name, and process wait channel message.
|
|
.It Cm /a
|
|
show the kernel virtual addresses of each process'
|
|
proc structure, u-are, and vmspace structure.
|
|
The vmspace address is also the address of the process'
|
|
vm_map structure, and can be used in the
|
|
.Ic "show map"
|
|
command.
|
|
.It Cm /w
|
|
show each process' PID, command, system call emulation, wait channel
|
|
address, and wait channel message.
|
|
.El
|
|
.It Xo
|
|
.Sm off
|
|
.Ic ps
|
|
.Op Cm /a
|
|
.Op Cm /n
|
|
.Op Cm /w
|
|
.Sm on
|
|
.Xc
|
|
A synonym for
|
|
.Ic "show all procs" .
|
|
.It Ic "show registers" Ns Op Cm /u
|
|
Display the register set.
|
|
If
|
|
.Cm /u
|
|
is specified, display user registers instead of kernel registers
|
|
or the currently save one.
|
|
.Pp
|
|
Warning: support for
|
|
.Cm /u
|
|
is machine dependent.
|
|
If not supported, incorrect information will be displayed.
|
|
.It Xo
|
|
.Ic "show map" Ns Op Cm /f
|
|
.Ar address
|
|
.Xc
|
|
Print the vm_map at
|
|
.Ar address .
|
|
If
|
|
.Cm /f
|
|
is specified the complete map is printed.
|
|
.It Xo
|
|
.Ic "show object" Ns Op Cm /f
|
|
.Ar address
|
|
.Xc
|
|
Print the vm_object at
|
|
.Ar address .
|
|
If
|
|
.Cm /f
|
|
is specified the complete object is printed.
|
|
.It Ic "show watches"
|
|
Display all watchpoints.
|
|
.It Xo
|
|
.Ic watch
|
|
.Sm off
|
|
.Ar address
|
|
.Op Cm , Ar size
|
|
.Sm on
|
|
.Xc
|
|
Set a watchpoint for a region.
|
|
Execution stops when an attempt to modify the region occurs.
|
|
.Ar size
|
|
defaults to 4.
|
|
.Pp
|
|
If you specify a wrong space address, the request is
|
|
rejected with an error message.
|
|
.Pp
|
|
Warning: attempts to watch wired kernel memory may cause
|
|
an unrecoverable error in some systems such as i386.
|
|
Watchpoints on user addresses work the best.
|
|
.El
|
|
.Sh MACHINE-SPECIFIC COMMANDS
|
|
The "glue" code that hooks
|
|
.Nm
|
|
into the
|
|
.Nx
|
|
kernel for any given port can also add machine specific commands
|
|
to the
|
|
.Nm
|
|
command parser.
|
|
All of these commands are preceded by the command word
|
|
.Em machine
|
|
to indicate that they are part of the machine-specific command
|
|
set (e.g.
|
|
.Ic "machine reboot"
|
|
).
|
|
Some of these commands are:
|
|
.Ss ALPHA
|
|
.Bl -tag -width "intrchain"
|
|
.It Ic halt
|
|
Call the PROM monitor to halt the CPU.
|
|
.It Ic reboot
|
|
Call the PROM monitor to reboot the CPU.
|
|
.El
|
|
.Ss ARM32
|
|
.Bl -tag -width "intrchain"
|
|
.It Ic vmstat
|
|
Equivalent to
|
|
.Xr vmstat 8
|
|
output with "-s" option (statistics).
|
|
.It Ic vnode
|
|
Print out a description of a vnode.
|
|
.It Ic intrchain
|
|
Print the list of IRQ handlers.
|
|
.It Ic panic
|
|
Print the current "panic" string.
|
|
.It Ic frame
|
|
Given a trap frame address, print out the trap frame.
|
|
.El
|
|
.Ss MIPS
|
|
.Bl -tag -width "intrchain"
|
|
.It Ic halt
|
|
Call the PROM monitor to halt the CPU.
|
|
.It Ic tlb
|
|
Print out the Translation Lookaside Buffer (TLB).
|
|
.It Ic trapdump
|
|
Print out the Trap Log.
|
|
Only works in
|
|
.Nx
|
|
kernels compiled with
|
|
.Dv DEBUG
|
|
option.
|
|
.El
|
|
.Ss SPARC
|
|
.Bl -tag -width "intrchain"
|
|
.It Ic prom
|
|
Exit to the Sun PROM monitor.
|
|
.El
|
|
.Ss SUN3 and SUN3X
|
|
.Bl -tag -width "intrchain"
|
|
.It Ic abort
|
|
Drop into monitor via abort (allows continue).
|
|
.It Ic halt
|
|
Exit to Sun PROM monitor as in
|
|
.Xr halt 8 .
|
|
.It Ic reboot
|
|
Reboot the machine as in
|
|
.Xr reboot 8 .
|
|
.It Ic pgmap
|
|
Given an address, print the address, segment map, page map, and
|
|
Page Table Entry (PTE).
|
|
.El
|
|
.Sh VARIABLES
|
|
.Nm
|
|
accesses registers and variables as
|
|
.Cm $ Ns Ar name .
|
|
Register names are as per the
|
|
.Ic "show registers"
|
|
command.
|
|
Some variables are suffixed with numbers, and may have a modifier
|
|
following a colon immediately after the variable name.
|
|
For example, register variables may have a
|
|
.Sq u
|
|
modifier to indicate user register
|
|
(e.g.,
|
|
.Li "$eax:u" ) .
|
|
.Pp
|
|
Built-in variables currently supported are:
|
|
.Bl -tag -offset indent -width "maxwidth"
|
|
.It Va lines
|
|
The number of lines.
|
|
This is used by the
|
|
.Ic more
|
|
feature.
|
|
.It Va maxoff
|
|
Addresses are printed as
|
|
.Li 'symbol'+offset
|
|
unless
|
|
.Li offset
|
|
is greater than
|
|
.Va maxoff .
|
|
.It Va maxwidth
|
|
The width of the displayed line.
|
|
.It Va onpanic
|
|
If non-zero (the default),
|
|
.Nm
|
|
will be invoked when the kernel panics.
|
|
If the kernel configuration option
|
|
.D1 Cd options DDB_ONPANIC=0
|
|
is used,
|
|
.Va onpanic
|
|
will be initialised to off.
|
|
.It Va radix
|
|
Input and output radix.
|
|
.It Va tabstops
|
|
Tab stop width.
|
|
.It Va work Ns Sy xx
|
|
Temporary work variable.
|
|
.Sq Sy xx
|
|
is between 0 and 31.
|
|
.El
|
|
.Pp
|
|
All built-in variables are accessible via
|
|
.Xr sysctl 3 .
|
|
.Sh EXPRESSIONS
|
|
Almost all expression operators in C are supported, except
|
|
.Sq ~ ,
|
|
.Sq ^ ,
|
|
and unary
|
|
.Sq & .
|
|
Special rules in
|
|
.Nm
|
|
are:
|
|
.Bl -tag -offset indent -width "identifier"
|
|
.It Ar identifier
|
|
name of a symbol.
|
|
It is translated to the address (or value) of it.
|
|
.Sq .
|
|
and
|
|
.Sq :
|
|
can be used in the identifier.
|
|
If supported by an object format dependent routine,
|
|
.Sm off
|
|
.Xo
|
|
.Oo Ar filename : Oc
|
|
.Ar function
|
|
.Oo : Ar "line number" Oc ,
|
|
.Xc
|
|
.Xo
|
|
.Oo Ar filename : Oc
|
|
.Ar variable ,
|
|
.Xc
|
|
and
|
|
.Xo
|
|
.Ar filename
|
|
.Oo : Ar "line number" Oc ,
|
|
.Xc
|
|
.Sm on
|
|
can be accepted as a symbol.
|
|
The symbol may be prefixed with
|
|
.Ar "symbol_table_name" Ns ::
|
|
(e.g.,
|
|
.Li emulator::mach_msg_trap )
|
|
to specify other than kernel symbols.
|
|
.It Ar number
|
|
number.
|
|
Radix is determined by the first two characters:
|
|
.Sq 0x
|
|
- hex,
|
|
.Sq 0o
|
|
- octal,
|
|
.Sq 0t
|
|
- decimal,
|
|
otherwise follow current radix.
|
|
.It Cm .
|
|
.Ar dot
|
|
.It Cm +
|
|
.Ar next
|
|
.It Cm ..
|
|
address of the start of the last line examined.
|
|
Unlike
|
|
.Ar dot
|
|
or
|
|
.Ar next ,
|
|
this is only changed by the
|
|
.Ic examine
|
|
or
|
|
.Ic write
|
|
commands.
|
|
.It Cm ,
|
|
last address explicitly specified.
|
|
.It Cm $ Ns Ar name
|
|
register name or variable.
|
|
It is translated to the value of it.
|
|
It may be followed by a
|
|
.Sq :
|
|
and modifiers as described above.
|
|
.It Cm a
|
|
multiple of right-hand side.
|
|
.It Cm * Ns Ar expr
|
|
expression indirection.
|
|
It may be followed by a
|
|
.Sq :
|
|
and modifiers as described above.
|
|
.El
|
|
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
kernel debugger was written as part of the MACH project at
|
|
Carnegie-Mellon University.
|
|
.Sh SEE ALSO
|
|
.Xr options 4 ,
|
|
.Xr sysctl 8
|