NAME
config
—
build kernel compilation
directories
SYNOPSIS
config |
[-dMPpSv ] [-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
- Issue diagnostic output for debugging problems with
config
itself. More-d
options (currently up to 5) produce more output. -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. -S
- Use suffix rules and build objects under subdirectories (experimental).
-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.
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.