Commit 6a121588 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kconfig: remove 'optional' property support 



The 'choice' statement is primarily used to exclusively select one
option, but the 'optional' property allows all entries to be disabled.

In the following example, both A and B can be disabled simultaneously:

    choice
            prompt "choose A, B, or nothing"
            optional

    config A
            bool "A"

    config B
            bool "B"

    endchoice

You can achieve the equivalent outcome by other means.

A common solution is to add another option to guard the choice block.
In the following example, you can set ENABLE_A_B_CHOICE=n to disable
the entire choice block:

    choice
            prompt "choose A or B"
            depends on ENABLE_A_B_CHOICE

    config A
            bool "A"

    config B
            bool "B"

    endchoice

Another approach is to insert one more entry:

    choice
            prompt "choose A, B, or disable both"

    config A
            bool "A"

    config B
            bool "B"

    config DISABLE_A_AND_B
            bool "choose this to disable both A and B"

    endchoice

Some real examples are DEBUG_INFO_NONE, INITRAMFS_COMPRESSION_NONE,
LTO_NONE, etc.

The 'optional' property is even more unnecessary for a tristate choice.

Without the 'optional' property, you can disable A and B; you can set
'm' in the choice prompt, and disable A and B individually:

    choice
            prompt "choose one built-in or make them modular"

    config A
            tristate "A"

    config B
            tristate "B"

    endchoice

In conclusion, the 'optional' property was unneeded.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: default avatarNicolas Schier <n.schier@avm.de>
parent d9a1dab6

Documentation/kbuild/kconfig-language.rst

+0 −3
Original line number Diff line number Diff line
@@ -410,9 +410,6 @@ to be set to 'm'. This can be used if multiple drivers for a single 
hardware exists and only a single driver can be compiled/loaded into

the kernel, but all drivers can be compiled as modules.



A choice accepts another option "optional", which allows to set the

choice to 'n' and no entry needs to be selected.



comment::



	"comment" <prompt>

scripts/kconfig/confdata.c

+1 −4
Original line number Diff line number Diff line
@@ -810,9 +810,6 @@ int conf_write_defconfig(const char *filename) 
			/*

			 * If symbol is a choice value and equals to the

			 * default for a choice - skip.

			 * But only if value is bool and equal to "y" and

			 * choice is not "optional".

			 * (If choice is "optional" then all values can be "n")

			 */

			if (sym_is_choice_value(sym)) {

				struct symbol *cs;
@@ -820,7 +817,7 @@ int conf_write_defconfig(const char *filename) 


				cs = prop_get_symbol(sym_get_choice_prop(sym));

				ds = sym_choice_default(cs);

				if (!sym_is_optional(cs) && sym == ds) {

				if (sym == ds) {

					if ((sym->type == S_BOOLEAN) &&

					    sym_get_tristate_value(sym) == yes)

						continue;

scripts/kconfig/expr.h

+0 −1
Original line number Diff line number Diff line
@@ -132,7 +132,6 @@ struct symbol { 
#define SYMBOL_CHECK      0x0008  /* used during dependency checking */

#define SYMBOL_CHOICEVAL  0x0020  /* used as a value in a choice block */

#define SYMBOL_VALID      0x0080  /* set when symbol.curr is calculated */

#define SYMBOL_OPTIONAL   0x0100  /* choice is optional - values can be 'n' */

#define SYMBOL_WRITE      0x0200  /* write symbol to file (KCONFIG_CONFIG) */

#define SYMBOL_CHANGED    0x0400  /* ? */

#define SYMBOL_WRITTEN    0x0800  /* track info to avoid double-write to .config */

scripts/kconfig/gconf.c

+0 −2
Original line number Diff line number Diff line
@@ -87,8 +87,6 @@ static const char *dbg_sym_flags(int val) 
		strcat(buf, "choiceval/");

	if (val & SYMBOL_VALID)

		strcat(buf, "valid/");

	if (val & SYMBOL_OPTIONAL)

		strcat(buf, "optional/");

	if (val & SYMBOL_WRITE)

		strcat(buf, "write/");

	if (val & SYMBOL_CHANGED)

scripts/kconfig/lexer.l

+0 −1
Original line number Diff line number Diff line
@@ -120,7 +120,6 @@ n [A-Za-z0-9_-] 
"menuconfig"		return T_MENUCONFIG;

"modules"		return T_MODULES;

"on"			return T_ON;

"optional"		return T_OPTIONAL;

"prompt"		return T_PROMPT;

"range"			return T_RANGE;

"select"		return T_SELECT;