xref: /freebsd/usr.sbin/config/config.8 (revision 4abd7edcbde21ba7a089c7d1a0bba8f87ebece06)
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28.\"     @(#)config.8	8.2 (Berkeley) 4/19/94
29.\" $FreeBSD$
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31.Dd May 8, 2007
32.Dt CONFIG 8
33.Os
34.Sh NAME
35.Nm config
36.Nd build system configuration files
37.Sh SYNOPSIS
38.Nm
39.Op Fl CVgp
40.Op Fl d Ar destdir
41.Ar SYSTEM_NAME
42.Nm
43.Op Fl x Ar kernel
44.Sh DESCRIPTION
45The
46.Nm
47utility builds a set of system configuration files from the file
48.Ar SYSTEM_NAME
49which describes
50the system to configure.
51A second file
52tells
53.Nm
54what files are needed to generate a system and
55can be augmented by configuration specific set of files
56that give alternate files for a specific machine
57(see the
58.Sx FILES
59section below).
60.Pp
61Available options and operands:
62.Bl -tag -width ".Ar SYSTEM_NAME"
63.It Fl V
64Print the
65.Nm
66version number.
67.It Fl C
68If the INCLUDE_CONFIG_FILE is present in a configuration file,
69kernel image will contain full configuration files included
70literally (preserving comments).
71This flag is kept for backward compatibility.
72.It Fl d Ar destdir
73Use
74.Ar destdir
75as the output directory, instead of the default one.
76Note that
77.Nm
78does not append
79.Ar SYSTEM_NAME
80to the directory given.
81.It Fl m
82Print the MACHINE and MACHINE_ARCH values for this
83kernel and exit.
84.It Fl g
85Configure a system for debugging.
86.It Fl x Ar kernel
87Print kernel configuration file embedded into a kernel
88file.
89This option makes sense only if
90.Cd "options INCLUDE_CONFIG_FILE"
91entry was present in your configuration file.
92.It Fl p
93Configure a system for profiling; for example,
94.Xr kgmon 8
95and
96.Xr gprof 1 .
97If two or more
98.Fl p
99options are supplied,
100.Nm
101configures a system for high resolution profiling.
102.It Ar SYSTEM_NAME
103Specify the name of the system configuration file
104containing device specifications, configuration options
105and other system parameters for one system configuration.
106.El
107.Pp
108The
109.Nm
110utility should be run from the
111.Pa conf
112subdirectory of the system source (usually
113.Pa /sys/ Ns Va ARCH Ns Pa /conf ) ,
114where
115.Va ARCH
116represents one of the architectures supported by
117.Fx .
118The
119.Nm
120utility creates the directory
121.Pa ../compile/ Ns Ar SYSTEM_NAME
122or the one given with the
123.Fl d
124option
125as necessary and places all output files there.
126The output of
127.Nm
128consists of a number of files; for the
129.Tn i386 ,
130they are:
131.Pa Makefile ,
132used by
133.Xr make 1
134in building the system;
135header files,
136definitions of
137the number of various devices that will be compiled into the system.
138.Pp
139After running
140.Nm ,
141it is necessary to run
142.Dq Li make depend
143in the directory where the new makefile
144was created.
145The
146.Nm
147utility prints a reminder of this when it completes.
148.Pp
149If any other error messages are produced by
150.Nm ,
151the problems in the configuration file should be corrected and
152.Nm
153should be run again.
154Attempts to compile a system that had configuration errors
155are likely to fail.
156.Sh DEBUG KERNELS
157Traditional
158.Bx
159kernels are compiled without symbols due to the heavy load on the
160system when compiling a
161.Dq debug
162kernel.
163A debug kernel contains complete symbols for all the source files, and
164enables an experienced kernel programmer to analyse the cause of a problem.
165The
166debuggers available prior to
167.Bx 4.4 Lite
168were able to find some information
169from a normal kernel;
170.Xr gdb 1
171provides very little support for normal kernels, and a debug kernel is needed
172for any meaningful analysis.
173.Pp
174For reasons of history, time and space, building a debug kernel is not the
175default with
176.Fx :
177a debug kernel takes up to 30% longer to build and
178requires about 30 MB of disk storage in the build directory, compared to about 6
179MB for a non-debug kernel.
180A debug kernel is about 11 MB in size, compared to
181about 2 MB for a non-debug kernel.
182This space is used both in the root file
183system and at run time in memory.
184Use the
185.Fl g
186option to build a debug kernel.
187With this option,
188.Nm
189causes two kernel files to be built in the kernel build directory:
190.Bl -bullet
191.It
192.Pa kernel.debug
193is the complete debug kernel.
194.It
195.Pa kernel
196is a copy of the kernel with the debug symbols stripped off.
197This is equivalent
198to the normal non-debug kernel.
199.El
200.Pp
201There is currently little sense in installing and booting from a debug kernel,
202since the only tools available which use the symbols do not run on-line.
203There
204are therefore two options for installing a debug kernel:
205.Bl -bullet
206.It
207.Dq Li "make install"
208installs
209.Pa kernel
210in the root file system.
211.It
212.Dq Li "make install.debug"
213installs
214.Pa kernel.debug
215in the root file system.
216.El
217.Sh FILES
218.Bl -tag -width ".Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME" -compact
219.It Pa /sys/conf/files
220list of common files system is built from
221.It Pa /sys/conf/Makefile. Ns Va ARCH
222generic makefile for the
223.Va ARCH
224.It Pa /sys/conf/files. Ns Va ARCH
225list of
226.Va ARCH
227specific files
228.It Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME
229default kernel build directory for system
230.Ar SYSTEM_NAME
231on
232.Va ARCH .
233.El
234.Sh SEE ALSO
235.Xr config 5
236.Pp
237The
238.Sx SYNOPSIS
239portion of each device in section 4.
240.Rs
241.%T "Building 4.3 BSD UNIX System with Config"
242.Re
243.Sh HISTORY
244The
245.Nm
246utility appeared in
247.Bx 4.1 .
248.Pp
249Before support for
250.Fl x
251was introduced,
252.Cd "options INCLUDE_CONFIG_FILE"
253included entire configuration file that used to be embedded in
254the new kernel.
255This meant that
256.Xr strings 1
257could be used to extract it from a kernel:
258to extract the configuration information, you had to use
259the command:
260.Pp
261.Dl "strings -n 3 kernel | sed -n 's/^___//p'"
262.Sh BUGS
263The line numbers reported in error messages are usually off by one.
264