freebsd-dev/usr.sbin/config/config.8

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.\"     @(#)config.8	8.2 (Berkeley) 4/19/94
.\" $FreeBSD$
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.Dd July 4, 2001
.Dt CONFIG 8
.Os
.Sh NAME
.Nm config
.Nd build system configuration files
.Sh SYNOPSIS
.Nm
.Op Fl gp
.Op Fl d Ar destdir
.Ar SYSTEM_NAME
.Sh DESCRIPTION
This is the old version of the
.Nm
program.
It understands the old autoconfiguration scheme
used on the HP300, i386, DECstation, and derivative platforms.
The new version of
.Nm
is used with the
SPARC platform.
Only the version of
.Nm
applicable to the architecture that you are running
will be installed on your machine.
.Pp
.Nm
builds a set of system configuration files from the file
.Ar SYSTEM_NAME
which describes
the system to configure.
A second file
tells
.Nm
what files are needed to generate a system and
can be augmented by configuration specific set of files
that give alternate files for a specific machine
(see the
.Sx FILES
section below).
.Pp
Available options and operands:
.Bl -tag -width ".Ar SYSTEM_NAME"
.It Fl d Ar destdir
Use
.Ar destdir
as the output directory, instead of the default one.
Note that
.Nm
does not append
.Ar SYSTEM_NAME
to the directory given.
.It Fl g
Configure a system for debugging.
.It Fl p
Configure a system for profiling; for example,
.Xr kgmon 8
and
.Xr gprof 1 .
If two or more
.Fl p
options are supplied,
.Nm
configures a system for high resolution profiling.
.It Ar SYSTEM_NAME
Specify the name of the system configuration file
containing device specifications, configuration options
and other system parameters for one system configuration.
.El
.Pp
.Nm
should be run from the
.Pa conf
subdirectory of the system source (usually
.Pa /sys/ Ns Va ARCH Ns Pa /conf ) ,
where
.Va ARCH
represents one of the architectures supported by
.Fx .
.Nm
creates the directory
.Pa ../compile/ Ns Ar SYSTEM_NAME
or the one given with the
.Fl d
option
as necessary and places all output files there.
The output of
.Nm
consists of a number of files; for the
.Tn i386 ,
they are:
.Pa ioconf.c ,
a description
of what I/O devices are attached to the system;
.Pa Makefile ,
used by
.Xr make 1
in building the system;
header files,
definitions of
the number of various devices that will be compiled into the system.
.Pp
After running
.Nm ,
it is necessary to run
.Dq Li make depend
in the directory where the new makefile
was created.
.Nm
prints a reminder of this when it completes.
.Pp
If any other error messages are produced by
.Nm ,
the problems in the configuration file should be corrected and
.Nm
should be run again.
Attempts to compile a system that had configuration errors
are likely to fail.
.Pp
If the
.Cd "options INCLUDE_CONFIG_FILE"
is used in the configuration file the
entire input file is embedded in the new kernel.
This means that
.Xr strings 1
can be used to extract it from a kernel:
to extract the configuration information, use the command
.Pp
.Dl "strings kernel | grep ___"
.Sh DEBUG KERNELS
Traditional
.Bx
kernels compiled without symbols due to the heavy load on the
system when compiling a
.Dq debug
kernel.
A debug kernel contains complete symbols for all the source files, and
enables an experienced kernel programmer to analyse the cause of a problem.
The
debuggers available prior to
.Bx 4.4 Lite
were able to find some information
from a normal kernel;
.Xr gdb 1
provides very little support for normal kernels, and a debug kernel is needed
for any meaningful analysis.
.Pp
For reasons of history, time and space, building a debug kernel is not the
default with
.Fx :
a debug kernel takes up to 30% longer to build and
requires about 30 MB of disk storage in the build directory, compared to about 6
MB for a non-debug kernel.
A debug kernel is about 11 MB in size, compared to
about 2 MB for a non-debug kernel.
This space is used both in the root file
system and at run time in memory.
Use the
.Fl g
option to build a debug kernel.
With this option,
.Nm
causes two kernel files to be built in the kernel build directory:
.Bl -bullet
.It
.Pa kernel.debug
is the complete debug kernel.
.It
.Pa kernel
is a copy of the kernel with the debug symbols stripped off.
This is equivalent
to the normal non-debug kernel.
.El
.Pp
There is currently little sense in installing and booting from a debug kernel,
since the only tools available which use the symbols do not run on-line.
There
are therefore two options for installing a debug kernel:
.Bl -bullet
.It
.Dq Li "make install"
installs
.Pa kernel
in the root file system.
.It
.Dq Li "make install.debug"
installs
.Pa kernel.debug
in the root file system.
.El
.Sh FILES
.Bl -tag -width ".Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME" -compact
.It Pa /sys/conf/files
list of common files system is built from
.It Pa /sys/conf/Makefile. Ns Va ARCH
generic makefile for the
.Va ARCH
.It Pa /sys/conf/files. Ns Va ARCH
list of
.Va ARCH
specific files
.It Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME
default kernel build directory for system
.Ar SYSTEM_NAME
on
.Va ARCH .
.El
.Sh SEE ALSO
The
.Sx SYNOPSIS
portion of each device in section 4.
.Rs
.%T "Building 4.3 BSD UNIX System with Config"
.Re
.Sh BUGS
The line numbers reported in error messages are usually off by one.
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.1 .