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 use diffconfig to see the
  32differences between the previous and new .config files:
  33
  34        scripts/diffconfig .config.old .config | less
  35
  36______________________________________________________________________
  37Environment variables for '*config'
  38
  39KCONFIG_CONFIG
  40--------------------------------------------------
  41This environment variable can be used to specify a default kernel config
  42file name to override the default name of ".config".
  43
  44KCONFIG_OVERWRITECONFIG
  45--------------------------------------------------
  46If you set KCONFIG_OVERWRITECONFIG in the environment, Kconfig will not
  47break symlinks when .config is a symlink to somewhere else.
  48
  49______________________________________________________________________
  50Environment variables for '{allyes/allmod/allno/rand}config'
  51
  52KCONFIG_ALLCONFIG
  53--------------------------------------------------
  54(partially based on lkml email from/by Rob Landley, re: miniconfig)
  55--------------------------------------------------
  56The allyesconfig/allmodconfig/allnoconfig/randconfig variants can also
  57use the environment variable KCONFIG_ALLCONFIG as a flag or a filename
  58that contains config symbols that the user requires to be set to a
  59specific value.  If KCONFIG_ALLCONFIG is used without a filename where
  60KCONFIG_ALLCONFIG == "" or KCONFIG_ALLCONFIG == "1", "make *config"
  61checks for a file named "all{yes/mod/no/def/random}.config"
  62(corresponding to the *config command that was used) for symbol values
  63that are to be forced.  If this file is not found, it checks for a
  64file named "all.config" to contain forced values.
  65
  66This enables you to create "miniature" config (miniconfig) or custom
  67config files containing just the config symbols that you are interested
  68in.  Then the kernel config system generates the full .config file,
  69including symbols of your miniconfig file.
  70
  71This 'KCONFIG_ALLCONFIG' file is a config file which contains
  72(usually a subset of all) preset config symbols.  These variable
  73settings are still subject to normal dependency checks.
  74
  75Examples:
  76        KCONFIG_ALLCONFIG=custom-notebook.config make allnoconfig
  77or
  78        KCONFIG_ALLCONFIG=mini.config make allnoconfig
  79or
  80        make KCONFIG_ALLCONFIG=mini.config allnoconfig
  81
  82These examples will disable most options (allnoconfig) but enable or
  83disable the options that are explicitly listed in the specified
  84mini-config files.
  85
  86______________________________________________________________________
  87Environment variables for 'silentoldconfig'
  88
  89KCONFIG_NOSILENTUPDATE
  90--------------------------------------------------
  91If this variable has a non-blank value, it prevents silent kernel
  92config updates (requires explicit updates).
  93
  94KCONFIG_AUTOCONFIG
  95--------------------------------------------------
  96This environment variable can be set to specify the path & name of the
  97"auto.conf" file.  Its default value is "include/config/auto.conf".
  98
  99KCONFIG_TRISTATE
 100--------------------------------------------------
 101This environment variable can be set to specify the path & name of the
 102"tristate.conf" file.  Its default value is "include/config/tristate.conf".
 103
 104KCONFIG_AUTOHEADER
 105--------------------------------------------------
 106This environment variable can be set to specify the path & name of the
 107"autoconf.h" (header) file.
 108Its default value is "include/generated/autoconf.h".
 109
 110
 111======================================================================
 112menuconfig
 113--------------------------------------------------
 114
 115SEARCHING for CONFIG symbols
 116
 117Searching in menuconfig:
 118
 119        The Search function searches for kernel configuration symbol
 120        names, so you have to know something close to what you are
 121        looking for.
 122
 123        Example:
 124                /hotplug
 125                This lists all config symbols that contain "hotplug",
 126                e.g., HOTPLUG, HOTPLUG_CPU, MEMORY_HOTPLUG.
 127
 128        For search help, enter / followed TAB-TAB-TAB (to highlight
 129        <Help>) and Enter.  This will tell you that you can also use
 130        regular expressions (regexes) in the search string, so if you
 131        are not interested in MEMORY_HOTPLUG, you could try
 132
 133                /^hotplug
 134
 135______________________________________________________________________
 136User interface options for 'menuconfig'
 137
 138MENUCONFIG_COLOR
 139--------------------------------------------------
 140It is possible to select different color themes using the variable
 141MENUCONFIG_COLOR.  To select a theme use:
 142
 143        make MENUCONFIG_COLOR=<theme> menuconfig
 144
 145Available themes are:
 146  mono       => selects colors suitable for monochrome displays
 147  blackbg    => selects a color scheme with black background
 148  classic    => theme with blue background. The classic look
 149  bluetitle  => a LCD friendly version of classic. (default)
 150
 151MENUCONFIG_MODE
 152--------------------------------------------------
 153This mode shows all sub-menus in one large tree.
 154
 155Example:
 156        make MENUCONFIG_MODE=single_menu menuconfig
 157
 158
 159======================================================================
 160xconfig
 161--------------------------------------------------
 162
 163Searching in xconfig:
 164
 165        The Search function searches for kernel configuration symbol
 166        names, so you have to know something close to what you are
 167        looking for.
 168
 169        Example:
 170                Ctrl-F hotplug
 171        or
 172                Menu: File, Search, hotplug
 173
 174        lists all config symbol entries that contain "hotplug" in
 175        the symbol name.  In this Search dialog, you may change the
 176        config setting for any of the entries that are not grayed out.
 177        You can also enter a different search string without having
 178        to return to the main menu.
 179
 180
 181======================================================================
 182gconfig
 183--------------------------------------------------
 184
 185Searching in gconfig:
 186
 187        None (gconfig isn't maintained as well as xconfig or menuconfig);
 188        however, gconfig does have a few more viewing choices than
 189        xconfig does.
 190
 191###
 192
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