Ubuntu Manpage: config — kernel configuration file format

Provided by: freebsd-buildutils_10.3~svn296373-7_amd64

NAME

       config — kernel configuration file format

DESCRIPTION

A kernel configuration file specifies the configuration of a FreeBSD kernel. It is processed by
config(8) to create a build environment where a kernel may be built using make(1).

Lexical Structure
A kernel configuration file comprises a sequence of specification directives.

A specification directive starts with a keyword at the beginning of the line and is followed by
additional parameters.

A specification directive may be terminated by a semicolon ‘;’ or by a newline. Long input lines may be
broken into shorter lines by starting the second and subsequent lines with a white space character.

Case is significant, “machine” and “MACHINE” are different tokens.

A double quote character ‘"’ starts a quoted string. All characters up to the next quote character form
the value of the quoted string. A ‘"’ character may be inserted into a quoted string by using the
sequence ‘\"’.

Numbers are specified using C-style syntax.

A ‘#’ character starts a comment; all characters from the ‘#’ character till the end of the current line
are ignored.

Whitespace between tokens is ignored, except inside quoted strings. Whitespace following a comment line
is ignored.

Configuration Directives
Kernel configuration directives may appear in any order in a kernel configuration file. Directives are
processed in order of appearance with subsequent directive lines overriding the effect of prior ones.

The list of keywords and their meanings are as follows:

cpu cputype
Specify the CPU this kernel will run on. There can be more than one cpu directive in a
configuration file. The allowed list of CPU names is architecture specific and is defined in the
file sys/conf/options.⟨arch⟩.

device name [, name [...]]
devices name [, name [...]]
Configures the specified devices for inclusion into the kernel image. Devices that are common to
all architectures are defined in the file sys/conf/files. Devices that are specific to
architecture arch are defined in the file sys/conf/files.⟨arch⟩.

env filename
Specifies a filename containing a kernel environment definition. The kernel normally uses an
environment prepared for it at boot time by loader(8). This directive makes the kernel ignore
the boot environment and use the compiled-in environment instead.

This directive is useful for setting kernel tunables in embedded environments that do not start
from loader(8).

files filename
Specifies a file containing a list of files specific to that kernel configuration file (a la
files.⟨arch⟩).

hints filename
Specifies a file to load a static device configuration specification from. From FreeBSD 5.0
onwards, the kernel reads the system's device configuration at boot time (see device.hints(5)).
This directive configures the kernel to use the static device configuration listed in filename.
The file filename must conform to the syntax specified by device.hints(5). Multiple hints lines
are allowed. The resulting hints will be the files concatenated in the order of appearance.

ident name
Set the kernel name to name. At least one ident directive is required.

include filename
Read subsequent text from file filename and return to the current file after filename is
successfully processed.

machine arch [cpuarch]
Specifies the architecture of the machine the kernel is being compiled for. Legal values for
arch include:

alpha The DEC Alpha architecture.
arm The ARM architecture.
amd64 The AMD x86-64 architecture.
i386 The Intel x86 based PC architecture.
ia64 The Intel IA64 architecture.
mips The MIPS architecture.
pc98 The PC98 architecture.
powerpc The IBM PowerPC architecture.
sparc64 The Sun Sparc64 architecture.

If argument cpuarch is specified, it points config(8) to the cpu architecture of the machine.
Currently the pc98 architecture requires its cpu architecture to be set to i386. When cpuarch is
not specified, it is assumed to be the same as arch. arch corresponds to MACHINE. cpuarch
corresponds to MACHINE_ARCH.

A kernel configuration file may have only one machine directive.

makeoption options
makeoptions options
Add options to the generated makefile.

The options argument is a comma separated list of one or more option specifications. Each option
specification has the form

MakeVariableName[=Value]
MakeVariableName+=Value

and results in the appropriate make(1) variable definition being inserted into the generated
makefile. If only the name of the make(1) variable is specified, value is assumed to be the
empty string.

Example:
makeoptions MYMAKEOPTION="foo"
makeoptions MYMAKEOPTION+="bar"
makeoptions MYNULLMAKEOPTION

maxusers number
This optional directive is used to configure the size of some kernel data structures. The
parameter number can be 0 (the default) or an integer greater than or equal to 2. A value of 0
indicates that the kernel should configure its data structures according to the size of available
physical memory. If auto configuration is requested, the kernel will set this tunable to a value
between 32 and 384.

As explained in tuning(7), this tunable can also be set at boot time using loader(8).

nocpu cputype
Remove the specified CPU from the list of previously selected CPUs. This directive can be used
to cancel the effect of cpu directives in files included using include.

nodevice name [, name [...]]
nodevices name [, name [...]]
Remove the specified devices from the list of previously selected devices. This directive can be
used to cancel the effects of device or devices directives in files included using include.

nomakeoption name
nomakeoptions name
Removes previously defined make(1) option name from the kernel build. This directive can be used
to cancel the effects of makeoption directives in files included using include.

nooption name [, name [...]]
nooptions name [, name [...]]
Remove the specified kernel options from the list of previously defined options. This directive
can be used to cancel the effects of option or options directives in files included using
include.

option optionspec [, optionspec [...]]
options optionspec [, optionspec [...]]
Add compile time kernel options to the kernel build. Each option specification has the form

name[=value]

If value is not specified, it is assumed to be NULL. Options common to all architectures are
specified in the file sys/conf/options. Options specific to architecture arch are specified in
the file sys/conf/options.⟨arch⟩.

profile number
Enables kernel profiling if number is non-zero. If number is 2 or greater, the kernel is
configured for high-resolution profiling. Kernels can also be built for profiling using the -p
option to config(8).

Obsolete Directives
The following kernel configuration directives are obsolete.

config This directive was used to specify the device to be used for the root file system. From
FreeBSD 4.0 onwards, this information is passed to a booting kernel by loader(8).

FILES

       sys/compile/NAME        Compile directory created from a kernel configuration.
       sys/conf/Makefile.arch  Makefile fragments for architecture arch.
       sys/conf/files          Devices common to all architectures.
       sys/conf/files.arch     Devices for architecture arch.
       sys/conf/options        Options common to all architectures.
       sys/conf/options.arch   Options for architecture arch.

HISTORY

       The config(8) utility first appeared in 4.1BSD, and was subsequently revised in 4.4BSD.

       The  kernel  configuration  mechanism  changed  further  in FreeBSD 4.0 and FreeBSD 5.0, moving toward an
       architecture supporting dynamic kernel configuration.

Debian                                          December 3, 2005                                       CONFIG(5)

NAME

DESCRIPTION

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SEE ALSO

HISTORY