linux/scripts/kconfig/zconf.gperf
Nicolas Pitre 237e3ad0f1 Kconfig: Introduce the "imply" keyword
The "imply" keyword is a weak version of "select" where the target
config symbol can still be turned off, avoiding those pitfalls that come
with the "select" keyword.

This is useful e.g. with multiple drivers that want to indicate their
ability to hook into a secondary subsystem while allowing the user to
configure that subsystem out without also having to unset these drivers.

Currently, the same effect can almost be achieved with:

config DRIVER_A
	tristate

config DRIVER_B
	tristate

config DRIVER_C
	tristate

config DRIVER_D
	tristate

[...]

config SUBSYSTEM_X
	tristate
	default DRIVER_A || DRIVER_B || DRIVER_C || DRIVER_D || [...]

This is unwieldy to maintain especially with a large number of drivers.
Furthermore, there is no easy way to restrict the choice for SUBSYSTEM_X
to y or n, excluding m, when some drivers are built-in. The "select"
keyword allows for excluding m, but it excludes n as well. Hence
this "imply" keyword.  The above becomes:

config DRIVER_A
	tristate
	imply SUBSYSTEM_X

config DRIVER_B
	tristate
	imply SUBSYSTEM_X

[...]

config SUBSYSTEM_X
	tristate

This is much cleaner, and way more flexible than "select". SUBSYSTEM_X
can still be configured out, and it can be set as a module when none of
the drivers are configured in or all of them are modular.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: linux-kbuild@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Michal Marek <mmarek@suse.com>
Cc: Edward Cree <ecree@solarflare.com>
Link: http://lkml.kernel.org/r/1478841010-28605-2-git-send-email-nicolas.pitre@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-11-16 09:26:33 +01:00

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%language=ANSI-C
%define hash-function-name kconf_id_hash
%define lookup-function-name kconf_id_lookup
%define string-pool-name kconf_id_strings
%compare-strncmp
%enum
%pic
%struct-type
struct kconf_id;
static const struct kconf_id *kconf_id_lookup(register const char *str, register unsigned int len);
%%
mainmenu, T_MAINMENU, TF_COMMAND
menu, T_MENU, TF_COMMAND
endmenu, T_ENDMENU, TF_COMMAND
source, T_SOURCE, TF_COMMAND
choice, T_CHOICE, TF_COMMAND
endchoice, T_ENDCHOICE, TF_COMMAND
comment, T_COMMENT, TF_COMMAND
config, T_CONFIG, TF_COMMAND
menuconfig, T_MENUCONFIG, TF_COMMAND
help, T_HELP, TF_COMMAND
---help---, T_HELP, TF_COMMAND
if, T_IF, TF_COMMAND|TF_PARAM
endif, T_ENDIF, TF_COMMAND
depends, T_DEPENDS, TF_COMMAND
optional, T_OPTIONAL, TF_COMMAND
default, T_DEFAULT, TF_COMMAND, S_UNKNOWN
prompt, T_PROMPT, TF_COMMAND
tristate, T_TYPE, TF_COMMAND, S_TRISTATE
def_tristate, T_DEFAULT, TF_COMMAND, S_TRISTATE
bool, T_TYPE, TF_COMMAND, S_BOOLEAN
boolean, T_TYPE, TF_COMMAND, S_BOOLEAN
def_bool, T_DEFAULT, TF_COMMAND, S_BOOLEAN
int, T_TYPE, TF_COMMAND, S_INT
hex, T_TYPE, TF_COMMAND, S_HEX
string, T_TYPE, TF_COMMAND, S_STRING
select, T_SELECT, TF_COMMAND
imply, T_IMPLY, TF_COMMAND
range, T_RANGE, TF_COMMAND
visible, T_VISIBLE, TF_COMMAND
option, T_OPTION, TF_COMMAND
on, T_ON, TF_PARAM
modules, T_OPT_MODULES, TF_OPTION
defconfig_list, T_OPT_DEFCONFIG_LIST,TF_OPTION
env, T_OPT_ENV, TF_OPTION
allnoconfig_y, T_OPT_ALLNOCONFIG_Y,TF_OPTION
%%