.\" Copyright (c) 2004 Marcel Moolenaar
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.\"
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.\" $FreeBSD: head/devel/gdb/files/kgdb/kgdb.1 440447 2017-05-08 19:02:25Z jhb $
.\"
.Dd October 11, 2006
.Dt KGDB 1
.Os
.Sh NAME
.Nm kgdb
.Nd "kernel debugger"
.Sh SYNOPSIS
.Nm
.Op Fl a | Fl f | Fl fullname
.Op Fl b Ar rate
.Op Fl q | Fl quiet
.Op Fl v
.Op Fl w
.Op Fl d Ar crashdir
.Op Fl c Ar core | Fl n Ar dumpnr | Fl r Ar device
.Op Ar kernel Op Ar core
.Sh DESCRIPTION
The
.Nm
utility is a debugger based on
.Xr gdb 1
that allows debugging of kernel core files.
.Pp
The options are as follows:
.Bl -tag -width ".Fl d Ar crashdir"
.It Fl a
Increase the annotation level.
An annotation level of 1 features the historical
.Fl fullname
option of
.Xr gdb 1 .
This is useful when running
.Nm
in Emacs.
The
.Fl f
or
.Fl fullname
options are supported for backward compatibility as well.
.It Fl b Ar rate
Set the baudrate to
.Ar rate .
.It Fl q
Suppress printing of the banner when the debugger starts.
The
.Fl quiet
form is supported for compatibility as well.
.It Fl v
Increase verbosity.
.It Fl w
Opens kmem-based targets in read-write mode.
(This is identical to what
.Fl -wcore
used to do in previous
gdb versions for
.Fx . )
.It Fl d Ar crashdir
Use
.Ar crashdir
instead of the default,
.Pa /var/crash
to locate kernel core dump files in.
The name
.Pa vmcore.
plus the dump number will be appended to determine
the actual dump file name.
.It Fl c Ar core
Explicitly use
.Ar core
as the core dump file.
.It Fl n Ar dumpnr
Use the kernel core dump file numbered
.Ar dumpnr
for debugging.
.It Fl r Ar device
Use
.Ar device
to connect
.Nm
to for a remote debugging session.
.El
.Pp
The
.Fl c , n ,
and
.Fl r
options are mutually exclusive.
.Pp
Optionally, the name of the kernel symbol file and
the name of the core dump file can be supplied on the
command-line as positional arguments.
If no kernel symbol file name has been given, the
symbol file of the currently running kernel will be
used.
If no core dump file has been specified through either
of the options or the last command-line argument,
.Pa /dev/mem
will be opened to allow debugging the currently running
kernel.
.Sh FILES
.Bl -tag -width ".Pa /var/crash"
.It Pa /dev/mem
Default memory image to open if no core dump file
has been specified.
.It Pa /var/crash
Default directory to locate kernel core dump files.
.El
.Sh SEE ALSO
.Xr gdb 1
.Sh HISTORY
The
.Nm
utility first appeared in its current form in
.Fx 5.3 .