config
—
build system configuration files
config |
[-CVgp ] [-I
path] [-d
destdir] [-s
srcdir] SYSTEM_NAME |
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 specific machine (see
the FILES section below).
Available options and operands:
-V
- Print the
config
version number.
-C
- If the INCLUDE_CONFIG_FILE is present in a configuration file, kernel
image will contain full configuration files included literally (preserving
comments). This flag is kept for backward compatibility.
-I
path
- Search in path for any file included by the
include
directive. This option may be specified
more than once.
-d
destdir
- Use destdir as the output directory, instead of the
default one. Note that
config
does not append
SYSTEM_NAME to the directory given.
-s
srcdir
- Use srcdir as the source directory, instead of the
default one.
-m
- Print the MACHINE and MACHINE_ARCH values for this kernel and exit.
-g
- Configure a system for debugging.
-x
kernel
- Print kernel configuration file embedded into a kernel file. This option
makes sense only if
options INCLUDE_CONFIG_FILE
entry was present in your configuration file.
-p
- Configure a system for profiling; for example,
kgmon(8)
and
gprof(1).
If two or more
-p
options are supplied,
config
configures 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 architectures
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:
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.
The config
utility looks for kernel
sources in the directory ../.. or the one given with
the -s
option.
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.
Attempts to compile a system that had configuration errors are likely to
fail.
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 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;
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 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:
- “
make install
” installs
kernel in the root file system.
- “
make install.debug
” installs
kernel.debug in the root file system.
- /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.
config(5)
The SYNOPSIS portion of each
device in section 4.
S. J. Leffler and
M. J. Karels, Building 4.3 BSD
UNIX System with Config, 4.4BSD System Manager's
Manual (SMM).
The config
utility appeared in
4.1BSD.
Before support for -x
was introduced,
options INCLUDE_CONFIG_FILE
included entire
configuration file that used to be embedded in the new kernel. This meant
that
strings(1)
could be used to extract it from a kernel: to extract the configuration
information, you had to use the command:
strings -n 3 kernel | sed -n
's/^___//p'
The line numbers reported in error messages are usually off by one.