From 76df6815dab76d7890936dc5f6d91cf7e7f88358 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Mon, 15 Dec 2025 15:06:54 -0800 Subject: [PATCH] kconfig: Support conditional deps using "depends on X if Y" Extend the "depends on" syntax to support conditional dependencies using "depends on X if Y". While functionally equivalent to "depends on X || (Y == n)", "depends on X if Y" is much more readable and makes the kconfig language uniform in supporting the "if " suffix. This also improves readability for "optional" dependencies, which are the subset of conditional dependencies where X is Y. Previously such optional dependencies had to be expressed as the counterintuitive "depends on X || !X", now this can be represented as "depends on X if X". The change is implemented by converting the "X if Y" syntax into the "X || (Y == n)" syntax during "depends on" token processing. Signed-off-by: Nicolas Pitre [Graham Roff: Rewrote commit message, updated patch, added tests] Signed-off-by: Graham Roff Acked-by: Randy Dunlap Link: https://patch.msgid.link/20251215-kconfig_conditional_deps-v3-1-59519af0a5df@qti.qualcomm.com [nathan: Minor adjustments to spacing] Signed-off-by: Nathan Chancellor --- Documentation/kbuild/kconfig-language.rst | 22 +++++++++++-- scripts/kconfig/lkc.h | 2 +- scripts/kconfig/menu.c | 12 ++++++- scripts/kconfig/parser.y | 6 ++-- scripts/kconfig/tests/conditional_dep/Kconfig | 32 +++++++++++++++++++ .../kconfig/tests/conditional_dep/__init__.py | 14 ++++++++ .../tests/conditional_dep/expected_config1 | 11 +++++++ .../tests/conditional_dep/expected_config2 | 9 ++++++ .../tests/conditional_dep/expected_config3 | 11 +++++++ .../tests/conditional_dep/test_config1 | 6 ++++ .../tests/conditional_dep/test_config2 | 7 ++++ .../tests/conditional_dep/test_config3 | 6 ++++ 12 files changed, 130 insertions(+), 8 deletions(-) create mode 100644 scripts/kconfig/tests/conditional_dep/Kconfig create mode 100644 scripts/kconfig/tests/conditional_dep/__init__.py create mode 100644 scripts/kconfig/tests/conditional_dep/expected_config1 create mode 100644 scripts/kconfig/tests/conditional_dep/expected_config2 create mode 100644 scripts/kconfig/tests/conditional_dep/expected_config3 create mode 100644 scripts/kconfig/tests/conditional_dep/test_config1 create mode 100644 scripts/kconfig/tests/conditional_dep/test_config2 create mode 100644 scripts/kconfig/tests/conditional_dep/test_config3 diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst index abce88f15d7cb..9ff3e530b2b43 100644 --- a/Documentation/kbuild/kconfig-language.rst +++ b/Documentation/kbuild/kconfig-language.rst @@ -118,7 +118,7 @@ applicable everywhere (see syntax). This is a shorthand notation for a type definition plus a value. Optionally dependencies for this default value can be added with "if". -- dependencies: "depends on" +- dependencies: "depends on" ["if" ] This defines a dependency for this menu entry. If multiple dependencies are defined, they are connected with '&&'. Dependencies @@ -134,6 +134,16 @@ applicable everywhere (see syntax). bool "foo" default y + The dependency definition itself may be conditional by appending "if" + followed by an expression. For example:: + + config FOO + tristate + depends on BAR if BAZ + + meaning that FOO is constrained by the value of BAR only if BAZ is + also set. + - reverse dependencies: "select" ["if" ] While normal dependencies reduce the upper limit of a symbol (see @@ -602,8 +612,14 @@ Some drivers are able to optionally use a feature from another module or build cleanly with that module disabled, but cause a link failure when trying to use that loadable module from a built-in driver. -The most common way to express this optional dependency in Kconfig logic -uses the slightly counterintuitive:: +The recommended way to express this optional dependency in Kconfig logic +uses the conditional form:: + + config FOO + tristate "Support for foo hardware" + depends on BAR if BAR + +This slightly counterintuitive style is also widely used:: config FOO tristate "Support for foo hardware" diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h index 56548efc14d70..7989859612156 100644 --- a/scripts/kconfig/lkc.h +++ b/scripts/kconfig/lkc.h @@ -82,7 +82,7 @@ void menu_warn(const struct menu *menu, const char *fmt, ...); struct menu *menu_add_menu(void); void menu_end_menu(void); void menu_add_entry(struct symbol *sym, enum menu_type type); -void menu_add_dep(struct expr *dep); +void menu_add_dep(struct expr *dep, struct expr *cond); void menu_add_visibility(struct expr *dep); struct property *menu_add_prompt(enum prop_type type, const char *prompt, struct expr *dep); diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c index 0f1a6513987c8..b2d8d4e11e07c 100644 --- a/scripts/kconfig/menu.c +++ b/scripts/kconfig/menu.c @@ -127,8 +127,18 @@ static struct expr *rewrite_m(struct expr *e) return e; } -void menu_add_dep(struct expr *dep) +void menu_add_dep(struct expr *dep, struct expr *cond) { + if (cond) { + /* + * We have "depends on X if Y" and we want: + * Y != n --> X + * Y == n --> y + * That simplifies to: (X || (Y == n)) + */ + dep = expr_alloc_or(dep, + expr_trans_compare(cond, E_EQUAL, &symbol_no)); + } current_entry->dep = expr_alloc_and(current_entry->dep, dep); } diff --git a/scripts/kconfig/parser.y b/scripts/kconfig/parser.y index 49b79dde1725a..6d1bbee38f5d1 100644 --- a/scripts/kconfig/parser.y +++ b/scripts/kconfig/parser.y @@ -323,7 +323,7 @@ if_entry: T_IF expr T_EOL { printd(DEBUG_PARSE, "%s:%d:if\n", cur_filename, cur_lineno); menu_add_entry(NULL, M_IF); - menu_add_dep($2); + menu_add_dep($2, NULL); $$ = menu_add_menu(); }; @@ -422,9 +422,9 @@ help: help_start T_HELPTEXT /* depends option */ -depends: T_DEPENDS T_ON expr T_EOL +depends: T_DEPENDS T_ON expr if_expr T_EOL { - menu_add_dep($3); + menu_add_dep($3, $4); printd(DEBUG_PARSE, "%s:%d:depends on\n", cur_filename, cur_lineno); }; diff --git a/scripts/kconfig/tests/conditional_dep/Kconfig b/scripts/kconfig/tests/conditional_dep/Kconfig new file mode 100644 index 0000000000000..2015dfbce2b15 --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/Kconfig @@ -0,0 +1,32 @@ +# SPDX-License-Identifier: GPL-2.0 +# Test Kconfig file for conditional dependencies. + +# Enable module support for tristate testing +config MODULES + bool "Enable loadable module support" + modules + default y + +config FOO + bool "FOO symbol" + +config BAR + bool "BAR symbol" + +config TEST_BASIC + bool "Test basic conditional dependency" + depends on FOO if BAR + default y + +config TEST_COMPLEX + bool "Test complex conditional dependency" + depends on (FOO && BAR) if (FOO || BAR) + default y + +config BAZ + tristate "BAZ symbol" + +config TEST_OPTIONAL + tristate "Test simple optional dependency" + depends on BAZ if BAZ + default y diff --git a/scripts/kconfig/tests/conditional_dep/__init__.py b/scripts/kconfig/tests/conditional_dep/__init__.py new file mode 100644 index 0000000000000..ab16df6487ec5 --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/__init__.py @@ -0,0 +1,14 @@ +# SPDX-License-Identifier: GPL-2.0 +""" +Correctly handle conditional dependencies. +""" + +def test(conf): + assert conf.oldconfig('test_config1') == 0 + assert conf.config_matches('expected_config1') + + assert conf.oldconfig('test_config2') == 0 + assert conf.config_matches('expected_config2') + + assert conf.oldconfig('test_config3') == 0 + assert conf.config_matches('expected_config3') diff --git a/scripts/kconfig/tests/conditional_dep/expected_config1 b/scripts/kconfig/tests/conditional_dep/expected_config1 new file mode 100644 index 0000000000000..826ed7f541b8b --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/expected_config1 @@ -0,0 +1,11 @@ +# +# Automatically generated file; DO NOT EDIT. +# Main menu +# +CONFIG_MODULES=y +CONFIG_FOO=y +CONFIG_BAR=y +CONFIG_TEST_BASIC=y +CONFIG_TEST_COMPLEX=y +CONFIG_BAZ=m +CONFIG_TEST_OPTIONAL=m diff --git a/scripts/kconfig/tests/conditional_dep/expected_config2 b/scripts/kconfig/tests/conditional_dep/expected_config2 new file mode 100644 index 0000000000000..10d2354f687f5 --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/expected_config2 @@ -0,0 +1,9 @@ +# +# Automatically generated file; DO NOT EDIT. +# Main menu +# +CONFIG_MODULES=y +# CONFIG_FOO is not set +CONFIG_BAR=y +CONFIG_BAZ=y +CONFIG_TEST_OPTIONAL=y diff --git a/scripts/kconfig/tests/conditional_dep/expected_config3 b/scripts/kconfig/tests/conditional_dep/expected_config3 new file mode 100644 index 0000000000000..b04fa6fdfeb48 --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/expected_config3 @@ -0,0 +1,11 @@ +# +# Automatically generated file; DO NOT EDIT. +# Main menu +# +CONFIG_MODULES=y +# CONFIG_FOO is not set +# CONFIG_BAR is not set +CONFIG_TEST_BASIC=y +CONFIG_TEST_COMPLEX=y +# CONFIG_BAZ is not set +CONFIG_TEST_OPTIONAL=y diff --git a/scripts/kconfig/tests/conditional_dep/test_config1 b/scripts/kconfig/tests/conditional_dep/test_config1 new file mode 100644 index 0000000000000..9b05f3ce8a99b --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/test_config1 @@ -0,0 +1,6 @@ +# Basic check that everything can be configured if selected. +CONFIG_FOO=y +CONFIG_BAR=y +CONFIG_BAZ=m +# Ensure that TEST_OPTIONAL=y with BAZ=m is converted to TEST_OPTIONAL=m +CONFIG_TEST_OPTIONAL=y diff --git a/scripts/kconfig/tests/conditional_dep/test_config2 b/scripts/kconfig/tests/conditional_dep/test_config2 new file mode 100644 index 0000000000000..5e66d230a836a --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/test_config2 @@ -0,0 +1,7 @@ +# If FOO is not selected, then TEST_BASIC should fail the conditional +# dependency since BAR is set. +# TEST_COMPLEX will fail dependency as it depends on both FOO and BAR +# if either of those is selected. +CONFIG_FOO=n +CONFIG_BAR=y +CONFIG_BAZ=y diff --git a/scripts/kconfig/tests/conditional_dep/test_config3 b/scripts/kconfig/tests/conditional_dep/test_config3 new file mode 100644 index 0000000000000..86304f3aa5574 --- /dev/null +++ b/scripts/kconfig/tests/conditional_dep/test_config3 @@ -0,0 +1,6 @@ +# If FOO is not selected, but BAR is also not selected, then TEST_BASIC +# should pass since the dependency on FOO is conditional on BAR. +# TEST_COMPLEX should be also set since neither FOO nor BAR are selected +# so it has no dependencies. +CONFIG_FOO=n +CONFIG_BAR=n -- 2.47.3