Documentation/kbuild/kconfig-language.rst

6 ------------
11 	+- Code maturity level options
12 	|  +- Prompt for development and/or incomplete code/drivers
13 	+- General setup
14 	|  +- Networking support
15 	|  +- System V IPC
16 	|  +- BSD Process Accounting
17 	|  +- Sysctl support
18 	+- Loadable module support
19 	|  +- Enable loadable module support
20 	|     +- Set version information on all module symbols
21 	|     +- Kernel module loader
22 	+- ...
29 ------------
50 ---------------
55 - type definition: "bool"/"tristate"/"string"/"hex"/"int"
69 - input prompt: "prompt" <prompt> ["if" <expr>]
73   with "if". If a prompt is not present, the config option is a non-visible
79 - default value: "default" <expr> ["if" <expr>]
108 	c) Sub-driver behavior or similar options for a driver that is
114 - type definition + default value::
121 - dependencies: "depends on" <expr>
128 	bool "foo" if BAR
129 	default y if BAR
133 	depends on BAR
134 	bool "foo"
137 - reverse dependencies: "select" <symbol> ["if" <expr>]
150 	By abusing select you are able to select a symbol FOO even
151 	if FOO depends on BAR that is not set.
152 	In general use select only for non-visible symbols
163 - weak reverse dependencies: "imply" <symbol> ["if" <expr>]
171     config FOO
172 	tristate "foo"
177 	depends on BAR
182 	FOO		BAR		BAZ's default	choice for BAZ
197   Note: If the feature provided by BAZ is highly desirable for FOO,
198   FOO should imply not only BAZ, but also its dependency BAR::
200     config FOO
201 	tristate "foo"
202 	imply BAR
209 - limiting menu display: "visible if" <expr>
217 - numerical ranges: "range" <symbol> <symbol> ["if" <expr>]
224 - help text: "help"
230 - module attribute: "modules"
236 -----------------
264 (4) If value of <symbol1> is respectively lower, greater, lower-or-equal,
265     or greater-or-equal than value of <symbol2>, it returns 'y',
268 (6) Returns the result of (2-/expr/).
276 There are two types of symbols: constant and non-constant symbols.
277 Non-constant symbols are the most common ones and are defined with the
278 'config' statement. Non-constant symbols consist entirely of alphanumeric
285 --------------
309 - the child entry must become invisible, if the parent is set to 'n'
310 - the child entry must only be visible, if the parent is visible::
328 --------------
334 - config
335 - menuconfig
336 - choice/endchoice
337 - comment
338 - menu/endmenu
339 - if/endif
340 - source
449 This sets the config program's title bar if the config program chooses
461 -------------
481 	depends on HAVE_GENERIC_IOMAP && FOO
485 	obj-$(CONFIG_GENERIC_IOMAP) += iomap.o
512 	depends on $(cc-option,-fstack-protector)
519 	def_bool $(success,$(srctree)/scripts/cc-check-foo.sh $(CC))
523 To restrict a component build to module-only, qualify its config symbol
526   config FOO
527 	depends on BAR && m
529 limits FOO to module (=m) or disabled (=n).
531 Compile-testing
537 it allows continuous-integration systems to compile-test the code on a more
539 Note that compile-tested code should avoid crashing when run on a system where
547 architectures and platforms. This is especially true for on-SoC IP cores,
559 Such a dependency can be relaxed by combining it with the compile-testing rule
562   config FOO
563 	bool "Support for foo hardware"
571 when trying to use that loadable module from a built-in driver.
576   config FOO
577 	tristate "Support for foo hardware"
578 	depends on BAR || !BAR
580 This means that there is either a dependency on BAR that disallows
581 the combination of FOO=y with BAR=m, or BAR is completely disabled. The BAR
582 module must provide all the stubs for !BAR case.
587   config FOO
588 	tristate "Support for foo hardware"
592 	def_tristate BAR || !BAR
595 the module code, useful for example when the module BAR does not provide
596 !BAR stubs::
601 			bar_register(&foo);
606 discarded, when CONFIG_BAR=m and this code is built-in. This is not what users
607 usually expect when enabling BAR as module.
629 Read: Documentation/kbuild/Kconfig.recursion-issue-01
633   make KBUILD_KCONFIG=Documentation/kbuild/Kconfig.recursion-issue-01 allnoconfig
638 Read: Documentation/kbuild/Kconfig.recursion-issue-02
642   make KBUILD_KCONFIG=Documentation/kbuild/Kconfig.recursion-issue-02 allnoconfig
651   a) Remove any superfluous "select FOO" or "depends on FOO"
654 	b1) Swap all "select FOO" to "depends on FOO" or,
656 	b2) Swap all "depends on FOO" to "select FOO"
659 Documentation/kbuild/Kconfig.recursion-issue-01 through the removal
665 Documentation/kbuild/Kconfig.recursion-issue-02.
674 06b718c01208    select A -> depends on A
675 c22eacfe82f9    depends on A -> depends on B
676 6a91e854442c    select A -> depends on A
677 118c565a8f2e    select A -> select B
678 f004e5594705    select A -> depends on A
679 c7861f37b4c6    depends on A -> (null)
680 80c69915e5fb    select A -> (null)              (1)
681 c2218e26c0d0    select A -> depends on A        (1)
682 d6ae99d04e1c    select A -> depends on A
683 95ca19cf8cbf    select A -> depends on A
684 8f057d7bca54    depends on A -> (null)
685 8f057d7bca54    depends on A -> select A
686 a0701f04846e    select A -> depends on A
687 0c8b92f7f259    depends on A -> (null)
688 e4e9e0540928    select A -> depends on A        (2)
690 7b1fff7e4fdf    select A -> depends on A
691 86c747d2a4f0    select A -> depends on A
692 d9f9ab51e55e    select A -> depends on A
693 0c51a4d8abd6    depends on A -> select A        (3)
694 e98062ed6dc4    select A -> depends on A        (3)
695 91e5d284a7f1    select A -> (null)
749 .. [1] https://gsd.uwaterloo.ca/sites/default/files/vm-2013-berger.pdf
750 .. [2] https://gsd.uwaterloo.ca/sites/default/files/ase241-berger_0.pdf
763 propositional formula extracted from CPP #ifdefs and build-rules into a SAT
770 https://kernelnewbies.org/KernelProjects/kconfig-sat
772 .. [4] https://www.cs.cornell.edu/~sabhar/chapters/SATSolvers-KR-Handbook.pdf
773 .. [5] https://gsd.uwaterloo.ca/sites/default/files/vm-2013-berger.pdf