home | help 
CONFIG(8)		     System Manager's Manual		       CONFIG(8)

NAME
     config -- build system configuration files

SYNOPSIS
     config [-gp] [-d destdir] SYSTEM_NAME

DESCRIPTION
     This  is the old version of the config utility.  It understands the old au-
     toconfiguration scheme used on the HP300, i386, DECstation, and  derivative
     platforms.   The  new  version  of  config is used with the SPARC platform.
     Only the version of config applicable to the architecture that you are run-
     ning 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 alternate files  for  a  spe-
     cific machine (see the "FILES" section below).

     Available options and operands:

     -d destdir   Use  destdir	as  the output directory, instead of the default
		  one.	Note that config does not append SYSTEM_NAME to the  di-
		  rectory 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 con-
		  figures a system for high resolution profiling.

     SYSTEM_NAME  Specify the name of the system configuration	file  containing
		  device  specifications, configuration options and other system
		  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 architec-
     tures  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: ioconf.c, a description of what I/O de-
     vices are attached to the system; 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.  At-
     tempts  to  compile  a  system  that had configuration errors are likely to
     fail.

     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 configu-
     ration 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 debug kernel contains
     complete symbols for all the source files, and enables an experienced  ker-
     nel  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  ker-
     nel;  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 option to build
     a	debug  kernel.	 With  this option, config causes two kernel files to be
     built in the kernel build directory:

     *	 kernel.debug is the complete debug kernel.

     *	 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 ker-
     nel,  since  the  only tools available which use the symbols do not run on-
     line.  There are therefore two options for installing a debug kernel:

     *	 "make install" installs kernel in the root file system.

     *	 "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.

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

HISTORY
     The config utility appeared in 4.1BSD.

FreeBSD 5.4			  July 4, 2001			       CONFIG(8)
home | help