xref: /freebsd/usr.sbin/config/config.8 (revision 830940567b49bb0c08dfaed40418999e76616909)
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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 g
82Configure a system for debugging.
83.It Fl x Ar kernel
84Print kernel configuration file embedded into a kernel
85file.
86This option makes sense only if
87.Cd "options INCLUDE_CONFIG_FILE"
88entry was present in your configuration file.
89.It Fl p
90Configure a system for profiling; for example,
91.Xr kgmon 8
92and
93.Xr gprof 1 .
94If two or more
95.Fl p
96options are supplied,
97.Nm
98configures a system for high resolution profiling.
99.It Ar SYSTEM_NAME
100Specify the name of the system configuration file
101containing device specifications, configuration options
102and other system parameters for one system configuration.
103.El
104.Pp
105The
106.Nm
107utility should be run from the
108.Pa conf
109subdirectory of the system source (usually
110.Pa /sys/ Ns Va ARCH Ns Pa /conf ) ,
111where
112.Va ARCH
113represents one of the architectures supported by
114.Fx .
115The
116.Nm
117utility creates the directory
118.Pa ../compile/ Ns Ar SYSTEM_NAME
119or the one given with the
120.Fl d
121option
122as necessary and places all output files there.
123The output of
124.Nm
125consists of a number of files; for the
126.Tn i386 ,
127they are:
128.Pa Makefile ,
129used by
130.Xr make 1
131in building the system;
132header files,
133definitions of
134the number of various devices that will be compiled into the system.
135.Pp
136After running
137.Nm ,
138it is necessary to run
139.Dq Li make depend
140in the directory where the new makefile
141was created.
142The
143.Nm
144utility prints a reminder of this when it completes.
145.Pp
146If any other error messages are produced by
147.Nm ,
148the problems in the configuration file should be corrected and
149.Nm
150should be run again.
151Attempts to compile a system that had configuration errors
152are likely to fail.
153.Sh DEBUG KERNELS
154Traditional
155.Bx
156kernels are compiled without symbols due to the heavy load on the
157system when compiling a
158.Dq debug
159kernel.
160A debug kernel contains complete symbols for all the source files, and
161enables an experienced kernel programmer to analyse the cause of a problem.
162The
163debuggers available prior to
164.Bx 4.4 Lite
165were able to find some information
166from a normal kernel;
167.Xr gdb 1
168provides very little support for normal kernels, and a debug kernel is needed
169for any meaningful analysis.
170.Pp
171For reasons of history, time and space, building a debug kernel is not the
172default with
173.Fx :
174a debug kernel takes up to 30% longer to build and
175requires about 30 MB of disk storage in the build directory, compared to about 6
176MB for a non-debug kernel.
177A debug kernel is about 11 MB in size, compared to
178about 2 MB for a non-debug kernel.
179This space is used both in the root file
180system and at run time in memory.
181Use the
182.Fl g
183option to build a debug kernel.
184With this option,
185.Nm
186causes two kernel files to be built in the kernel build directory:
187.Bl -bullet
188.It
189.Pa kernel.debug
190is the complete debug kernel.
191.It
192.Pa kernel
193is a copy of the kernel with the debug symbols stripped off.
194This is equivalent
195to the normal non-debug kernel.
196.El
197.Pp
198There is currently little sense in installing and booting from a debug kernel,
199since the only tools available which use the symbols do not run on-line.
200There
201are therefore two options for installing a debug kernel:
202.Bl -bullet
203.It
204.Dq Li "make install"
205installs
206.Pa kernel
207in the root file system.
208.It
209.Dq Li "make install.debug"
210installs
211.Pa kernel.debug
212in the root file system.
213.El
214.Sh FILES
215.Bl -tag -width ".Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME" -compact
216.It Pa /sys/conf/files
217list of common files system is built from
218.It Pa /sys/conf/Makefile. Ns Va ARCH
219generic makefile for the
220.Va ARCH
221.It Pa /sys/conf/files. Ns Va ARCH
222list of
223.Va ARCH
224specific files
225.It Pa /sys/ Ns Va ARCH Ns Pa /compile/ Ns Ar SYSTEM_NAME
226default kernel build directory for system
227.Ar SYSTEM_NAME
228on
229.Va ARCH .
230.El
231.Sh SEE ALSO
232.Xr config 5
233.Pp
234The
235.Sx SYNOPSIS
236portion of each device in section 4.
237.Rs
238.%T "Building 4.3 BSD UNIX System with Config"
239.Re
240.Sh HISTORY
241The
242.Nm
243utility appeared in
244.Bx 4.1 .
245.Pp
246Before support for
247.Fl x
248was introduced,
249.Cd "options INCLUDE_CONFIG_FILE"
250included entire configuration file that used to be embedded in
251the new kernel.
252This meant that
253.Xr strings 1
254could be used to extract it from a kernel:
255to extract the configuration information, you had to use
256the command:
257.Pp
258.Dl "strings -n 3 kernel | sed -n 's/^___//p'"
259.Sh BUGS
260The line numbers reported in error messages are usually off by one.
261