xref: /freebsd/usr.sbin/config/config.8 (revision fe6060f10f634930ff71b7c50291ddc610da2475)
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28.\"     @(#)config.8	8.2 (Berkeley) 4/19/94
29.\" $FreeBSD$
30.\"
31.Dd April 9, 2021
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 I Ar path
41.Op Fl d Ar destdir
42.Op Fl s Ar srcdir
43.Ar SYSTEM_NAME
44.Nm
45.Op Fl x Ar kernel
46.Sh DESCRIPTION
47The
48.Nm
49utility builds a set of system configuration files from the file
50.Ar SYSTEM_NAME
51which describes
52the system to configure.
53A second file
54tells
55.Nm
56what files are needed to generate a system and
57can be augmented by configuration specific set of files
58that give alternate files for a specific machine
59(see the
60.Sx FILES
61section below).
62.Pp
63Available options and operands:
64.Bl -tag -width "SYSTEM_NAME"
65.It Fl V
66Print the
67.Nm
68version number.
69.It Fl C
70If the INCLUDE_CONFIG_FILE is present in a configuration file,
71kernel image will contain full configuration files included
72literally (preserving comments).
73This flag is kept for backward compatibility.
74.It Fl I Ar path
75Search in
76.Ar path
77for any file included by the
78.Ic include
79directive.
80This option may be specified more than once.
81.It Fl d Ar destdir
82Use
83.Ar destdir
84as the output directory, instead of the default one.
85Note that
86.Nm
87does not append
88.Ar SYSTEM_NAME
89to the directory given.
90.It Fl s Ar srcdir
91Use
92.Ar srcdir
93as the source directory, instead of the default one.
94.It Fl m
95Print the MACHINE and MACHINE_ARCH values for this
96kernel and exit.
97.It Fl g
98Configure a system for debugging.
99.It Fl x Ar kernel
100Print kernel configuration file embedded into a kernel
101file.
102This option makes sense only if
103.Cd "options INCLUDE_CONFIG_FILE"
104entry was present in your configuration file.
105.It Ar SYSTEM_NAME
106Specify the name of the system configuration file
107containing device specifications, configuration options
108and other system parameters for one system configuration.
109.El
110.Pp
111The
112.Nm
113utility should be run from the
114.Pa conf
115subdirectory of the system source (usually
116.Pa /sys/ Ns Va ARCH Ns Pa /conf ) ,
117where
118.Va ARCH
119represents one of the architectures supported by
120.Fx .
121The
122.Nm
123utility creates the directory
124.Pa ../compile/ Ns Ar SYSTEM_NAME
125or the one given with the
126.Fl d
127option
128as necessary and places all output files there.
129The output of
130.Nm
131consists of a number of files; for the
132.Tn i386 ,
133they are:
134.Pa Makefile ,
135used by
136.Xr make 1
137in building the system;
138header files,
139definitions of
140the number of various devices that will be compiled into the system.
141.Pp
142The
143.Nm
144utility looks for kernel sources in the directory
145.Pa ../..
146or the one given with the
147.Fl s
148option.
149.Pp
150After running
151.Nm ,
152it is necessary to run
153.Dq Li make depend
154in the directory where the new makefile
155was created.
156The
157.Nm
158utility prints a reminder of this when it completes.
159.Pp
160If any other error messages are produced by
161.Nm ,
162the problems in the configuration file should be corrected and
163.Nm
164should be run again.
165Attempts to compile a system that had configuration errors
166are likely to fail.
167.Sh DEBUG KERNELS
168Traditional
169.Bx
170kernels are compiled without symbols due to the heavy load on the
171system when compiling a
172.Dq debug
173kernel.
174A debug kernel contains complete symbols for all the source files, and
175enables an experienced kernel programmer to analyse the cause of a problem.
176The
177debuggers available prior to
178.Bx 4.4 Lite
179were able to find some information
180from a normal kernel;
181.Xr gdb 1
182provides very little support for normal kernels, and a debug kernel is needed
183for any meaningful analysis.
184.Pp
185For reasons of history, time and space, building a debug kernel is not the
186default with
187.Fx :
188a debug kernel takes up to 30% longer to build and
189requires about 30 MB of disk storage in the build directory, compared to about 6
190MB for a non-debug kernel.
191A debug kernel is about 11 MB in size, compared to
192about 2 MB for a non-debug kernel.
193This space is used both in the root file
194system and at run time in memory.
195Use the
196.Fl g
197option to build a debug kernel.
198With this option,
199.Nm
200causes two kernel files to be built in the kernel build directory:
201.Bl -bullet
202.It
203.Pa kernel.debug
204is the complete debug kernel.
205.It
206.Pa kernel
207is a copy of the kernel with the debug symbols stripped off.
208This is equivalent
209to the normal non-debug kernel.
210.El
211.Pp
212There is currently little sense in installing and booting from a debug kernel,
213since the only tools available which use the symbols do not run on-line.
214There
215are therefore two options for installing a debug kernel:
216.Bl -bullet
217.It
218.Dq Li "make install"
219installs
220.Pa kernel
221in the root file system.
222.It
223.Dq Li "make install.debug"
224installs
225.Pa kernel.debug
226in the root file system.
227.El
228.Sh FILES
229.Bl -tag -width "/sys/ARCH/compile/SYSTEM_NAME" -compact
230.It Pa /sys/conf/files
231list of common files system is built from
232.It Pa /sys/conf/Makefile . Ns Va ARCH
233generic makefile for the
234.Va ARCH
235.It Pa /sys/conf/files . Ns Va ARCH
236list of
237.Va ARCH
238specific files
239.It Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME
240default kernel build directory for system
241.Ar SYSTEM_NAME
242on
243.Va ARCH .
244.El
245.Sh SEE ALSO
246.Xr config 5
247.Pp
248The
249.Sx SYNOPSIS
250portion of each device in section 4.
251.Rs
252.\" 4.4BSD SMM:2
253.%A S. J. Leffler
254.%A M. J. Karels
255.%T "Building 4.3 BSD UNIX System with Config"
256.%B 4.4BSD System Manager's Manual (SMM)
257.Re
258.Sh HISTORY
259The
260.Nm
261utility appeared in
262.Bx 4.1 .
263.Pp
264Before support for
265.Fl x
266was introduced,
267.Cd "options INCLUDE_CONFIG_FILE"
268included entire configuration file that used to be embedded in
269the new kernel.
270This meant that
271.Xr strings 1
272could be used to extract it from a kernel:
273to extract the configuration information, you had to use
274the command:
275.Pp
276.Dl "strings -n 3 kernel | sed -n 's/^___//p'"
277.Sh BUGS
278The line numbers reported in error messages are usually off by one.
279