linux/Documentation/kbuild/kconfig.txt
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   1This file contains some assistance for using "make *config".
   2
   3Use "make help" to list all of the possible configuration targets.
   4
   5The xconfig ('qconf') and menuconfig ('mconf') programs also
   6have embedded help text.  Be sure to check it for navigation,
   7search, and other general help text.
   8
   9======================================================================
  10General
  11--------------------------------------------------
  12
  13New kernel releases often introduce new config symbols.  Often more
  14important, new kernel releases may rename config symbols.  When
  15this happens, using a previously working .config file and running
  16"make oldconfig" won't necessarily produce a working new kernel
  17for you, so you may find that you need to see what NEW kernel
  18symbols have been introduced.
  19
  20To see a list of new config symbols when using "make oldconfig", use
  21
  22        cp user/some/old.config .config
  23        yes "" | make oldconfig >conf.new
  24
  25and the config program will list as (NEW) any new symbols that have
  26unknown values.  Of course, the .config file is also updated with
  27new (default) values, so you can use:
  28
  29        grep "(NEW)" conf.new
  30
  31to see the new config symbols or you can 'diff' the previous and
  32new .config files to see the differences:
  33
  34        diff .config.old .config | less
  35
  36(Yes, we need something better here.)
  37
  38
  39======================================================================
  40menuconfig
  41--------------------------------------------------
  42
  43SEARCHING for CONFIG symbols
  44
  45Searching in menuconfig:
  46
  47        The Search function searches for kernel configuration symbol
  48        names, so you have to know something close to what you are
  49        looking for.
  50
  51        Example:
  52                /hotplug
  53                This lists all config symbols that contain "hotplug",
  54                e.g., HOTPLUG, HOTPLUG_CPU, MEMORY_HOTPLUG.
  55
  56        For search help, enter / followed TAB-TAB-TAB (to highlight
  57        <Help>) and Enter.  This will tell you that you can also use
  58        regular expressions (regexes) in the search string, so if you
  59        are not interested in MEMORY_HOTPLUG, you could try
  60
  61                /^hotplug
  62
  63
  64______________________________________________________________________
  65Color Themes for 'menuconfig'
  66
  67It is possible to select different color themes using the variable
  68MENUCONFIG_COLOR.  To select a theme use:
  69
  70        make MENUCONFIG_COLOR=<theme> menuconfig
  71
  72Available themes are:
  73  mono       => selects colors suitable for monochrome displays
  74  blackbg    => selects a color scheme with black background
  75  classic    => theme with blue background. The classic look
  76  bluetitle  => a LCD friendly version of classic. (default)
  77
  78______________________________________________________________________
  79Environment variables in 'menuconfig'
  80
  81KCONFIG_ALLCONFIG
  82--------------------------------------------------
  83(partially based on lkml email from/by Rob Landley, re: miniconfig)
  84--------------------------------------------------
  85The allyesconfig/allmodconfig/allnoconfig/randconfig variants can
  86also use the environment variable KCONFIG_ALLCONFIG as a flag or a
  87filename that contains config symbols that the user requires to be
  88set to a specific value.  If KCONFIG_ALLCONFIG is used without a
  89filename, "make *config" checks for a file named
  90"all{yes/mod/no/random}.config" (corresponding to the *config command
  91that was used) for symbol values that are to be forced.  If this file
  92is not found, it checks for a file named "all.config" to contain forced
  93values.
  94
  95This enables you to create "miniature" config (miniconfig) or custom
  96config files containing just the config symbols that you are interested
  97in.  Then the kernel config system generates the full .config file,
  98including dependencies of your miniconfig file, based on the miniconfig
  99file.
 100
 101This 'KCONFIG_ALLCONFIG' file is a config file which contains
 102(usually a subset of all) preset config symbols.  These variable
 103settings are still subject to normal dependency checks.
 104
 105Examples:
 106        KCONFIG_ALLCONFIG=custom-notebook.config make allnoconfig
 107or
 108        KCONFIG_ALLCONFIG=mini.config make allnoconfig
 109or
 110        make KCONFIG_ALLCONFIG=mini.config allnoconfig
 111
 112These examples will disable most options (allnoconfig) but enable or
 113disable the options that are explicitly listed in the specified
 114mini-config files.
 115
 116KCONFIG_NOSILENTUPDATE
 117--------------------------------------------------
 118If this variable has a non-blank value, it prevents silent kernel
 119config udpates (requires explicit updates).
 120
 121KCONFIG_CONFIG
 122--------------------------------------------------
 123This environment variable can be used to specify a default kernel config
 124file name to override the default name of ".config".
 125
 126KCONFIG_OVERWRITECONFIG
 127--------------------------------------------------
 128If you set KCONFIG_OVERWRITECONFIG in the environment, Kconfig will not
 129break symlinks when .config is a symlink to somewhere else.
 130
 131KCONFIG_NOTIMESTAMP
 132--------------------------------------------------
 133If this environment variable exists and is non-null, the timestamp line
 134in generated .config files is omitted.
 135
 136KCONFIG_AUTOCONFIG
 137--------------------------------------------------
 138This environment variable can be set to specify the path & name of the
 139"auto.conf" file.  Its default value is "include/config/auto.conf".
 140
 141KCONFIG_AUTOHEADER
 142--------------------------------------------------
 143This environment variable can be set to specify the path & name of the
 144"autoconf.h" (header) file.  Its default value is "include/linux/autoconf.h".
 145
 146______________________________________________________________________
 147menuconfig User Interface Options
 148----------------------------------------------------------------------
 149MENUCONFIG_MODE
 150--------------------------------------------------
 151This mode shows all sub-menus in one large tree.
 152
 153Example:
 154        MENUCONFIG_MODE=single_menu make menuconfig
 155
 156======================================================================
 157xconfig
 158--------------------------------------------------
 159
 160Searching in xconfig:
 161
 162        The Search function searches for kernel configuration symbol
 163        names, so you have to know something close to what you are
 164        looking for.
 165
 166        Example:
 167                Ctrl-F hotplug
 168        or
 169                Menu: File, Search, hotplug
 170
 171        lists all config symbol entries that contain "hotplug" in
 172        the symbol name.  In this Search dialog, you may change the
 173        config setting for any of the entries that are not grayed out.
 174        You can also enter a different search string without having
 175        to return to the main menu.
 176
 177
 178======================================================================
 179gconfig
 180--------------------------------------------------
 181
 182Searching in gconfig:
 183
 184        None (gconfig isn't maintained as well as xconfig or menuconfig);
 185        however, gconfig does have a few more viewing choices than
 186        xconfig does.
 187
 188###
 189