================================= Configuration targets and editors

This file contains some assistance for using make *config.

Use make help to list all of the possible configuration targets.

The xconfig ('qconf'), menuconfig ('mconf'), and nconfig ('nconf') programs also have embedded help text. Be sure to check that for navigation, search, and other general help text.

The gconfig ('gconf') program has limited help text.

General

New kernel releases often introduce new config symbols. Often more important, new kernel releases may rename config symbols. When this happens, using a previously working .config file and running "make oldconfig" won't necessarily produce a working new kernel for you, so you may find that you need to see what NEW kernel symbols have been introduced.

To see a list of new config symbols, use::

cp user/some/old.config .config
make listnewconfig

and the config program will list any new symbols, one per line.

Alternatively, you can use the brute force method::

make oldconfig
scripts/diffconfig .config.old .config | less

Environment variables

Environment variables for *config:

KCONFIG_CONFIG This environment variable can be used to specify a default kernel config file name to override the default name of ".config".

KCONFIG_DEFCONFIG_LIST This environment variable specifies a list of config files which can be used as a base configuration in case the .config does not exist yet. Entries in the list are separated with whitespaces to each other, and the first one that exists is used.

KCONFIG_OVERWRITECONFIG If you set KCONFIG_OVERWRITECONFIG in the environment, Kconfig will not break symlinks when .config is a symlink to somewhere else.

KCONFIG_WARN_UNKNOWN_SYMBOLS This environment variable makes Kconfig warn about all unrecognized symbols in the config input.

KCONFIG_WERROR If set, Kconfig treats warnings as errors.

CONFIG_ If you set CONFIG_ in the environment, Kconfig will prefix all symbols with its value when saving the configuration, instead of using the default, CONFIG_.

Environment variables for {allyes/allmod/allno/alldef/rand}config:

KCONFIG_ALLCONFIG The allyesconfig/allmodconfig/alldefconfig/allnoconfig/randconfig variants can also use the environment variable KCONFIG_ALLCONFIG as a flag or a filename that contains config symbols that the user requires to be set to a specific value. If KCONFIG_ALLCONFIG is used without a filename where KCONFIG_ALLCONFIG == "" or KCONFIG_ALLCONFIG == "1", make *config checks for a file named "all{yes/mod/no/def/random}.config" (corresponding to the *config command that was used) for symbol values that are to be forced. If this file is not found, it checks for a file named "all.config" to contain forced values.

This enables you to create "miniature" config (miniconfig) or custom
config files containing just the config symbols that you are interested
in.  Then the kernel config system generates the full .config file,
including symbols of your miniconfig file.

This ``KCONFIG_ALLCONFIG`` file is a config file which contains
(usually a subset of all) preset config symbols.  These variable
settings are still subject to normal dependency checks.

Examples::

    KCONFIG_ALLCONFIG=custom-notebook.config make allnoconfig

or::

    KCONFIG_ALLCONFIG=mini.config make allnoconfig

or::

    make KCONFIG_ALLCONFIG=mini.config allnoconfig

These examples will disable most options (allnoconfig) but enable or
disable the options that are explicitly listed in the specified
mini-config files.

Environment variables for randconfig:

KCONFIG_SEED You can set this to the integer value used to seed the RNG, if you want to somehow debug the behaviour of the kconfig parser/frontends. If not set, the current time will be used.

KCONFIG_PROBABILITY This variable can be used to skew the probabilities. This variable can be unset or empty, or set to three different formats:

=======================     ==================  =====================
KCONFIG_PROBABILITY         y:n split           y:m:n split
=======================     ==================  =====================
unset or empty              50  : 50            33  : 33  : 34
N                            N  : 100-N         N/2 : N/2 : 100-N
[1] N:M                     N+M : 100-(N+M)      N  :  M  : 100-(N+M)
[2] N:M:L                    N  : 100-N          M  :  L  : 100-(M+L)
=======================     ==================  =====================

where N, M and L are integers (in base 10) in the range [0,100], and so that:

[1] N+M is in the range [0,100]

[2] M+L is in the range [0,100]

Examples::

KCONFIG_PROBABILITY=10
    10% of booleans will be set to 'y', 90% to 'n'
    5% of tristates will be set to 'y', 5% to 'm', 90% to 'n'
KCONFIG_PROBABILITY=15:25
    40% of booleans will be set to 'y', 60% to 'n'
    15% of tristates will be set to 'y', 25% to 'm', 60% to 'n'
KCONFIG_PROBABILITY=10:15:15
    10% of booleans will be set to 'y', 90% to 'n'
    15% of tristates will be set to 'y', 15% to 'm', 70% to 'n'

Environment variables for syncconfig:

KCONFIG_NOSILENTUPDATE If this variable has a non-blank value, it prevents silent kernel config updates (requires explicit updates).

KCONFIG_AUTOCONFIG This environment variable can be set to specify the path & name of the "auto.conf" file. Its default value is "include/config/auto.conf".

KCONFIG_AUTOHEADER This environment variable can be set to specify the path & name of the "autoconf.h" (header) file. Its default value is "include/generated/autoconf.h".

menuconfig

Searching in menuconfig:

The Search function searches for kernel configuration symbol
names, so you have to know something close to what you are
looking for.

Example::

    /hotplug
    This lists all config symbols that contain "hotplug",
    e.g., HOTPLUG_CPU, MEMORY_HOTPLUG.

For search help, enter / followed by TAB-TAB (to highlight
<Help>) and Enter.  This will tell you that you can also use
regular expressions (regexes) in the search string, so if you
are not interested in MEMORY_HOTPLUG, you could try::

    /^hotplug

When searching, symbols are sorted thus:

- first, exact matches, sorted alphabetically (an exact match
  is when the search matches the complete symbol name);
- then, other matches, sorted alphabetically.

For example, ^ATH.K matches:

    ATH5K ATH9K ATH5K_AHB ATH5K_DEBUG [...] ATH6KL ATH6KL_DEBUG
    [...] ATH9K_AHB ATH9K_BTCOEX_SUPPORT ATH9K_COMMON [...]

of which only ATH5K and ATH9K match exactly and so are sorted
first (and in alphabetical order), then come all other symbols,
sorted in alphabetical order.

In this menu, pressing the key in the (#) prefix will jump
directly to that location. You will be returned to the current
search results after exiting this new menu.

User interface options for 'menuconfig':

MENUCONFIG_COLOR It is possible to select different color themes using the variable MENUCONFIG_COLOR. To select a theme use::

    make MENUCONFIG_COLOR=<theme> menuconfig

Available themes are::

  - mono       => selects colors suitable for monochrome displays
  - blackbg    => selects a color scheme with black background
  - classic    => theme with blue background. The classic look
  - bluetitle  => a LCD friendly version of classic. (default)

MENUCONFIG_MODE This mode shows all sub-menus in one large tree.

Example::

    make MENUCONFIG_MODE=single_menu menuconfig

nconfig

nconfig is an alternate text-based configurator. It lists function keys across the bottom of the terminal (window) that execute commands. You can also just use the corresponding numeric key to execute the commands unless you are in a data entry window. E.g., instead of F6 for Save, you can just press 6.

Use F1 for Global help or F3 for the Short help menu.

Searching in nconfig:

You can search either in the menu entry "prompt" strings
or in the configuration symbols.

Use / to begin a search through the menu entries.  This does
not support regular expressions.  Use <Down> or <Up> for
Next hit and Previous hit, respectively.  Use <Esc> to
terminate the search mode.

F8 (SymSearch) searches the configuration symbols for the
given string or regular expression (regex).

In the SymSearch, pressing the key in the (#) prefix will
jump directly to that location. You will be returned to the
current search results after exiting this new menu.

Environment variables:

NCONFIG_MODE This mode shows all sub-menus in one large tree.

Example::

    make NCONFIG_MODE=single_menu nconfig

xconfig

Searching in xconfig:

The Search function searches for kernel configuration symbol
names, so you have to know something close to what you are
looking for.

Example::

    Ctrl-F hotplug

or::

    Menu: File, Search, hotplug

lists all config symbol entries that contain "hotplug" in
the symbol name.  In this Search dialog, you may change the
config setting for any of the entries that are not grayed out.
You can also enter a different search string without having
to return to the main menu.

gconfig

Searching in gconfig:

There is no search command in gconfig.  However, gconfig does
have several different viewing choices, modes, and options.