This file contains some assistance for using “make *config”.
Use “make help” to list all of the possible configuration targets.
The xconfig (‘qconf’) and menuconfig (‘mconf’) programs also
have embedded help text. Be sure to check it for navigation,
search, and other general help text.
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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 when using “make oldconfig”, use
cp user/some/old.config .config
yes "" | make oldconfig >conf.new
and the config program will list as (NEW) any new symbols that have
unknown values. Of course, the .config file is also updated with
new (default) values, so you can use:
grep "(NEW)" conf.new
to see the new config symbols or you can use diffconfig to see the
differences between the previous and new .config files:
scripts/diffconfig .config.old .config | less
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_OVERWRITECONFIG
If you set KCONFIG_OVERWRITECONFIG in the environment, Kconfig will not
break symlinks when .config is a symlink to somewhere else.
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/rand}config’
KCONFIG_ALLCONFIG
(partially based on lkml email from/by Rob Landley, re: miniconfig)
The allyesconfig/allmodconfig/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 ‘silentoldconfig’
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_TRISTATE
This environment variable can be set to specify the path & name of the
“tristate.conf” file. Its default value is “include/config/tristate.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”.
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menuconfig
SEARCHING for CONFIG symbols
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 TAB-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
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
======================================================================
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:
None (gconfig isn't maintained as well as xconfig or menuconfig);
however, gconfig does have a few more viewing choices than
xconfig does.
