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

NAME
     config -- build system configuration files

SYNOPSIS
     config [-CVgp] [-d	destdir] SYSTEM_NAME
     config [-x	kernel]

DESCRIPTION
     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.

     -C		  If the INCLUDE_CONFIG_FILE is	present	in a configuration
		  file,	kernel image will contain full configuration files
		  included literally (preserving comments).  This flag is kept
		  for backward compatibility.

     -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.

     -m		  Print	the MACHINE and	MACHINE_ARCH values for	this kernel
		  and exit.

     -g		  Configure a system for debugging.

     -x	kernel	  Print	kernel configuration file embedded into	a kernel file.
		  This option makes sense only if options INCLUDE_CONFIG_FILE
		  entry	was present in your configuration file.

     -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
     fail.

DEBUG KERNELS
     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.

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 specific files
     /sys/ARCH/compile/SYSTEM_NAME  default 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.

     Before support for	-x was introduced, options INCLUDE_CONFIG_FILE
     included entire configuration file	that used to be	embedded in the	new
     kernel.  This meant that strings(1) could be used to extract it from a
     kernel: to	extract	the configuration information, you had to use the com-
     mand:

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

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

FreeBSD	9.3			  May 8, 2007			   FreeBSD 9.3

NAME | SYNOPSIS | DESCRIPTION | DEBUG KERNELS | FILES | SEE ALSO | HISTORY | BUGS

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