path: root/usr.sbin/config/config.8

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.\"     @(#)config.8	8.2 (Berkeley) 4/19/94
.\"
.Dd April 19, 1994
.Dt CONFIG 8
.Os BSD 4
.Sh NAME
.Nm config
.Nd build system configuration files
.Sh SYNOPSIS
.Nm config
.Op Fl gpr
.Ar SYSTEM_NAME
.Sh DESCRIPTION
This is the old version of the
.Nm
program.
It understands the old autoconfiguration 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 
.Nm
applicable to the architecture that you are running
will be installed on your machine.
.Pp
.Nm Config
builds a set of system configuration files from the file
.Ar SYSTEM_NAME
which describes
the system to configure.
A second file
tells
.Nm
what files are needed to generate a system and
can be augmented by configuration specific set of files
that give alternate files for a specific machine
(see the
.Sx FILES
section below).
.Pp
Available options and operands:
.Pp
.Bl -tag -width SYSTEM_NAME
.It Fl g
Configure a system for debugging.  This is the default, so this flag has no
meaning, and causes a warning message to be printed.
.It Fl p
Configure a system for profiling; for example,
.Xr kgmon 8
and
.Xr gprof 1 .
If two or more
.Fl p
options are supplied,
.Nm
configures a system for high resolution profiling.
.It Fl r
Remove the old compile directory (see below).
.It Fl s
Configure a system without debugging symbols.  This saves both time and space,
but if problems occur with the kernel, it will be almost impossible to find out
their causes.
.It Ar SYSTEM_NAME
Specifies the name of the system configuration file
containing device specifications, configuration options
and other system parameters for one system configuration.
.El
.Pp
.Nm Config
should be run from the
.Pa conf
subdirectory of the system source (usually
.Pa /sys/ARCH/conf ) .
.Nm Config
will create the directory
.Pa ../../compile/SYSTEM_NAME
as necessary and place all output files there.
If the directory already exists and the
.Fl r
flag was specified, it will be removed first.
The output of
.Nm
consists of a number of files; for the
.Tn i386 ,
they are:
.Pa ioconf.c ,
a description
of what I/O devices are attached to the system;
.Pa vector.h ,
definitions of
macros related to counting interrupts;
.Pa Makefile ,
used by
.Xr make 1
in building the system;
header files,
definitions of
the number of various devices that will be compiled into the system;
so-called swap configuration files,
definitions for
the disk areas to be used for the root file system
and system dumps.
.Pp
After running
.Nm config ,
it is necessary to run
.Dq Li make depend
in the directory where the new makefile
was created.
.Nm Config
prints a reminder of this when it completes.
.Pp
If any other error messages are produced by
.Nm config ,
the problems in the configuration file should be corrected and
.Nm
should be run again.
Attempts to compile a system that had configuration errors
are likely to fail.
.Pp
If the option "INCLUDE_CONFIG_FILE" is used in the configuration file the 
entire input file is embedded in the new kernel.  This means that
.Xr strings 1
can be used to extract it from a kernel. 
.Pp
Strings | grep ___ will print just the configure information.
.Sh DEBUG KERNELS
Traditional BSD kernels were compiled without symbols due to the heavy load on
the system when compiling a 
.if n "debug"
.if t ``debug''
kernel.  A debug kernel contains complete symbols for all the source files, and
enables 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; this is no longer the case with
.Xr gdb 8 ,
and a debug kernel is needed for any meaningful analysis.
.Pp
Building a debug kernel is the default with FreeBSD, and the
.Fl s
option is required to revert to historical behaviour.  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.  Since kernel
storage is non-pageable, the additional space required by a debug kernel is lost
to the system when not debugging.
.Pp
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:
.Bl -bullet
.It
.Nm make
.Ar install
makes a stripped copy of the kernel and installs it in the root file system.
.It
.Nm make
.Ar install.debug
installs the complete debug kernel in the root file system.
.El
.Sh FILES
.Bl -tag -width /sys/i386/conf/Makefile.i386 -compact
.It Pa /sys/conf/files
list of common files system is built from
.It Pa /sys/i386/conf/Makefile.i386
generic makefile for the
.Tn i386
.It Pa /sys/i386/conf/files.i386
list of
.Tn i386
specific files
.It Pa /sys/i386/conf/devices.i386
name to major device mapping file for the
.Tn i386
.It Pa /sys/i386/conf/files. Ns Em ERNIE
list of files specific to
.Em ERNIE
system
.El
.Sh SEE ALSO
The SYNOPSIS portion of each device in section 4.
.Rs
.%T "Building 4.3 BSD UNIX System with Config"
.Re
.Sh BUGS
The line numbers reported in error messages are usually off by one.
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.1 .