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CONFIG(8)               FreeBSD System Manager's Manual              CONFIG(8)

     config -- build system configuration files

     config [-Vgp] [-d destdir] SYSTEM_NAME

     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 aug-
     mented by configuration specific set of files that give alternate 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, instead of the default
                  one.  Note that config does not append SYSTEM_NAME to the
                  directory given.

     -g           Configure a system for debugging.

     -p           Configure a system for profiling; for example, kgmon(8) and
                  gprof(1).  If two or more -p options are supplied, config
                  configures a system for high resolution profiling.

     SYSTEM_NAME  Specify the name of the system configuration file containing
                  device specifications, configuration options and other sys-
                  tem parameters for one system configuration.

     The config utility should be run from the conf subdirectory of the system
     source (usually /sys/ARCH/conf), where ARCH represents one of the archi-
     tectures 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

     If the options INCLUDE_CONFIG_FILE is used in the configuration 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 extract the con-
     figuration information, use the command

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

     Traditional BSD kernels are compiled without symbols due to the heavy
     load on the system when compiling a ``debug'' kernel.  A debug kernel
     contains complete symbols for all the source files, and enables an expe-
     rienced kernel programmer to analyse the cause of a problem.  The debug-
     gers available prior to 4.4BSD-Lite were able to find some information
     from a normal kernel; gdb(1) provides very little support for normal ker-
     nels, and a debug kernel is needed for any meaningful analysis.

     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 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 -g
     option to build a debug kernel.  With this option, config causes two ker-
     nel 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 system.

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

     /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 specific files
     /sys/ARCH/compile/SYSTEM_NAME  default kernel build directory for system
                                    SYSTEM_NAME on ARCH.


     The SYNOPSIS portion of each device in section 4.

     Building 4.3 BSD UNIX System with Config.

     The config utility appeared in 4.1BSD.

     The line numbers reported in error messages are usually off by one.

FreeBSD 6.2                    December 16, 2004                   FreeBSD 6.2


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