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CONFIG(1)                   General Commands Manual                  CONFIG(1)

NAME
     config -- build kernel compilation directories

SYNOPSIS
     config [-MPpv] [-b builddir] [-D var=value] [-s srcdir] [-U value]
            [config-file]
     config -x [kernel-file]
     config -L [-v] [-s srcdir] [config-file]

DESCRIPTION
     In its first synopsis form, config creates a kernel build directory from
     the machine description file config-file, which describes the system to
     configure.  Refer to section KERNEL BUILD CONFIGURATION for the details
     of that use of config.

     In its second synopsis form, config takes the binary kernel kernel-file
     as its single argument (aside from the mandatory -x flag), then extracts
     the embedded configuration file (if any) and writes it to standard
     output.  If kernel-file is not given, and the system is not running
     NetBSD an error is printed.  On systems running NetBSD the booted kernel
     is looked up using the sysctl(3) variable machdep.booted_kernel and if
     that is not found, _PATH_UNIX (/netbsd) is used.  Configuration data will
     be available if the given kernel was compiled with either
     INCLUDE_CONFIG_FILE or INCLUDE_JUST_CONFIG options.

     In its third synopsis form, config is a tool for the kernel developer and
     generates a ``lint'' configuration file to be used during regression
     testing.  Refer to section LINT CONFIGURATION for the details of that use
     of config.

     config accepts the following parameters:

     -b builddir
             Use builddir as the kernel build directory, instead of computing
             and creating one automatically.

     -D var=value
             Define a makeoptions variable to the given value.  This is
             equivalent to appending a makeoptions var=value line to the
             config file.

     -L      Generate a lint configuration.  See section LINT CONFIGURATION
             for details.

     -M      Do modular build (experimental).  Instead of linking all object
             files (*.o) at once, collect related object files into an
             intermediate relocatable object (*.ko), then link those *.ko
             files into the final kernel.  This changes the order of objects
             in the kernel binary.

     -P      Pack locators to save space in the resulting kernel binary.  The
             amount of space saved that way is so small that this option
             should be considered historical, and of no actual use.

     -p      Generate a build directory suited for kernel profiling.  However,
             this options should be avoided in favor of the relevant options
             inside the configuration file as described in section KERNEL
             BUILD CONFIGURATION.

     -s srcdir
             Point to the top of the kernel source tree.  It must be an
             absolute path when config is used to prepare a kernel build
             directory, but can be relative when it is used in combination
             with the -L flag.

     -U var  Undefine the makeoption var.  This is equivalent to appending the
             line no makeoptions var to the config file.

     -v      Increase verbosity by enabling some more warnings.

     -x      Extract the configuration embedded in a kernel binary.

   KERNEL BUILD CONFIGURATION
     There are several different ways to run the config program.  The
     traditional way is to run config from the conf subdirectory of the
     machine-specific directory of the system source (usually
     /sys/arch/MACHINE/conf, where MACHINE is one of vax, hp300, and so
     forth), and to specify as the config-file the name of a machine
     description file located in that directory.  config will by default
     create files in the directory ../compile/SYSTEMNAME, where SYSTEMNAME is
     the last path component of config-file.  config will assume that the top-
     level kernel source directory is located four directories above the build
     directory.

     Another way is to create the build directory yourself, place the machine
     description file in the build directory with the name CONFIG, and run
     config from within the build directory without specifying a config-file.
     config will then by default create files in the current directory.  If
     you run config this way, you must specify the location of the top-level
     kernel source directory using the -s option or by using the ``source''
     directive at the beginning of the machine description file.

     Finally, you can specify the build directory for config and run it from
     anywhere.  You can specify a build directory with the -b option or by
     using the ``build'' directive at the beginning of the machine description
     file.  You must specify the location of the top-level kernel source
     directory if you specify a build directory.

     If config-file is a binary kernel, config will try to extract the
     configuration file embedded into it, which will be present if that kernel
     was built either with INCLUDE_CONFIG_FILE or INCLUDE_JUST_CONFIG options.
     This work mode requires you to manually specify a build directory with
     the -b option, which implies the need to provide a source tree too.

     If the -p option is supplied, .PROF is appended to the default
     compilation directory name, and config acts as if the lines ``makeoptions
     PROF="-pg"'' and ``options GPROF'' appeared in the machine description
     file.  This will build a system that includes profiling code; see
     kgmon(8) and gprof(1).  The -p flag is expected to be used for
     ``one-shot'' profiles of existing systems; for regular profiling, it is
     probably wiser to create a separate machine description file containing
     the makeoptions line.

     The old undocumented -g flag is no longer supported.  Instead, use
     ``makeoptions DEBUG="-g"'' and (typically) ``options KGDB''.

     The output of config consists of a number of files, principally ioconf.c,
     a description of I/O devices that may be attached to the system; and a
     Makefile, used by make(1) in building the kernel.

     After running config, it is wise to run ``make depend'' in the directory
     where the new makefile was created.  config prints a reminder of this
     when it completes.

     If config stops due to errors, the problems reported should be corrected
     and config should be run again.  config attempts to avoid changing the
     compilation directory if there are configuration errors, but this code is
     not well-tested, and some problems (such as running out of disk space)
     are unrecoverable.

   LINT CONFIGURATION
     A so-called ``lint'' configuration should include everything from the
     kernel that can possibly be selected.  The rationale is to provide a way
     to reach all the code a user might select, in order to make sure all
     options and drivers compile without error for a given source tree.

     When used with the -L flag, config takes the regular configuration file
     config-file and prints on the standard output a configuration file that
     includes config-file, selects all options and file-systems the user can
     possibly select, and defines an instance of every possible attachment as
     described by the kernel option definition files used by config-file.

     The resulting configuration file is meant as a way to select all possible
     features in order to test that each of them compiles.  It is not meant to
     result in a kernel binary that can run on any hardware.

     Unlike the first synopsis form, the provided srcdir is relative to the
     current working directory.  In the first synopsis form, it is relative to
     the build directory.

SEE ALSO
     The SYNOPSIS portion of each device in section 4.

     options(4), config(5), config(9)

HISTORY
     The config command appeared in 4.1BSD.  It was completely revised in
     4.4BSD.  The -x option appeared in NetBSD 2.0.  The -L option appeared in
     NetBSD 5.0.

NetBSD 7.1.2                   October 10, 2014                   NetBSD 7.1.2