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authorNicolas Pitre <nicolas.pitre@linaro.org>2016-11-11 00:10:05 -0500
committerThomas Gleixner <tglx@linutronix.de>2016-11-16 09:26:33 +0100
commit237e3ad0f195d8fd34f1299e45f04793832a16fc (patch)
tree3c3a7fd7442cf28789ed878c918ed018701c343d /scripts/kconfig/expr.h
parent4b7e9cf9c84b09adc428e0433cd376b91f9c52a7 (diff)
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>
Diffstat (limited to 'scripts/kconfig/expr.h')
-rw-r--r--scripts/kconfig/expr.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 973b6f733368..a73f762c48d6 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -85,6 +85,7 @@ struct symbol {
struct property *prop;
struct expr_value dir_dep;
struct expr_value rev_dep;
+ struct expr_value implied;
};
#define for_all_symbols(i, sym) for (i = 0; i < SYMBOL_HASHSIZE; i++) for (sym = symbol_hash[i]; sym; sym = sym->next) if (sym->type != S_OTHER)
@@ -136,6 +137,7 @@ enum prop_type {
P_DEFAULT, /* default y */
P_CHOICE, /* choice value */
P_SELECT, /* select BAR */
+ P_IMPLY, /* imply BAR */
P_RANGE, /* range 7..100 (for a symbol) */
P_ENV, /* value from environment variable */
P_SYMBOL, /* where a symbol is defined */