config(8)

NAME

config - build system configuration files

SYNOPSIS

config [-Vgp] [-d destdir] SYSTEM_NAME

DESCRIPTION

This is the old version of the config utility. It under

stands the old

autoconfiguration scheme used on the HP300, i386, DECsta

tion, and derivative platforms. The new version of config is used with the

SPARC platform. Only the version of config applicable to the archi

tecture that you

are running will be installed on your machine.

The config utility builds a set of system configuration

files from the

file SYSTEM_NAME which describes the system to configure. A

second file

tells config what files are needed to generate a system and

can be augmented by configuration specific set of files that give al

ternate files

for a specific machine (see the FILES section below).

Available options and operands:

-V Print the config version number.

-d destdir Use destdir as the output directory, in

stead of the

default one. Note that config does not ap

pend

SYSTEM_NAME to the directory given.

-g Configure a system for debugging.

-p Configure a system for profiling; for exam

ple, kgmon(8)

and gprof(1). If two or more -p options

are supplied,

config configures a system for high resolu

tion profiling.

SYSTEM_NAME Specify the name of the system configura

tion file con

taining device specifications, configura

tion options and

other system parameters for one system con

figuration.

The config utility should be run from the conf subdirectory

of the system

source (usually /sys/ARCH/conf), where ARCH represents one

of the architectures supported by FreeBSD. The config utility creates

the directory

../compile/SYSTEM_NAME or the one given with the -d option

as necessary

and places all output files there. The output of config

consists of a

number of files; for the i386, they are: Makefile, used by

make(1) in

building the system; header files, definitions of the number

of various

devices that will be compiled into the system.

After running config, it is necessary to run ``make depend''

in the

directory where the new makefile was created. The config

utility prints

a reminder of this when it completes.

If any other error messages are produced by config, the

problems in the

configuration file should be corrected and config should be

run again.

Attempts to compile a system that had configuration errors

are likely to

fail.

If the options INCLUDE_CONFIG_FILE is used in the configura

tion file the

entire input file is embedded in the new kernel. This means

that

strings(1) can be used to extract it from a kernel: to ex

tract the configuration information, use the command

strings -n 3 kernel | sed -n 's/^___//p'

DEBUG KERNELS

Traditional BSD kernels are compiled without symbols due to

the heavy

load on the system when compiling a ``debug'' kernel. A de

bug kernel

contains complete symbols for all the source files, and en

ables an experienced kernel programmer to analyse the cause of a problem.

The debuggers available prior to 4.4BSD-Lite were able to find some

information

from a normal kernel; gdb(1) provides very little support

for normal kernels, and a debug kernel is needed for any meaningful analy

sis.

For reasons of history, time and space, building a debug

kernel is not

the default with FreeBSD: a debug kernel takes up to 30%

longer to build

and requires about 30 MB of disk storage in the build direc

tory, 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 -g

option to build a debug kernel. With this option, config

causes two kernel files to be built in the kernel build directory:

+o kernel.debug is the complete debug kernel.

+o kernel is a copy of the kernel with the debug symbols

stripped off.

This is equivalent to the normal non-debug kernel.

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:

+o ``make install'' installs kernel in the root file sys

tem.

+o ``make install.debug'' installs kernel.debug in the root

file system.

FILES

/sys/conf/files list

of common

files

system is

built

from

/sys/conf/Makefile.ARCH generic makefile

for

the ARCH

/sys/conf/files.ARCH list

of ARCH spe

cif

ic files

/sys/ARCH/compile/SYSTEM_NAME de

fault kernel

build

directory

for

system

SYSTEM_NAME

on

ARCH.

SEE ALSO

config(5)

The SYNOPSIS portion of each device in section 4.

Building 4.3 BSD UNIX System with Config.

HISTORY

The config utility appeared in 4.1BSD.

BUGS

The line numbers reported in error messages are usually off

by one.

BSD December 16, 2004

BSD