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

     config -- build system configuration files

     config [-CVgp] [-I	path] [-d destdir] SYSTEM_NAME
     config [-x	kernel]

     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 in-
		  cluded literally (preserving comments).  This	flag is	kept
		  for backward compatibility.

     -I	path	  Search in path for any file included by the include direc-
		  tive.	 This option may be specified more than	once.

     -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 direc-
     tory where	the new	makefile was created.  The config utility prints a re-
     minder 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

     Traditional BSD kernels are compiled without symbols due to the heavy
     load on the system	when compiling a "debug" kernel.  A debug kernel con-
     tains complete symbols for	all the	source files, and enables an experi-
     enced 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 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 op-
     tion 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 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.

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

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

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

BSD				  May 8, 2007				   BSD


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