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kconfig: change defconfig_list option to environment variable
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"defconfig_list" is a weird option that defines a static symbol that
declares the list of base config files in case the .config does not
exist yet.

This is quite different from other normal symbols; we just abused the
"string" type and the "default" properties to list out the input files.
They must be fixed values since these are searched for and loaded in
the parse stage.

It is an ugly hack, and should not exist in the first place. Providing
this feature as an environment variable is a saner approach.

Signed-off-by: Masahiro Yamada <[email protected]>
masahir0y committed Apr 14, 2021
1 parent 4066162 commit b75b0a8
Showing 12 changed files with 50 additions and 43 deletions.
5 changes: 0 additions & 5 deletions Documentation/kbuild/kconfig-language.rst
Original file line number Diff line number Diff line change
@@ -229,11 +229,6 @@ applicable everywhere (see syntax).
which can modify the behaviour of the menu entry and its config
symbol. These options are currently possible:

- "defconfig_list"
This declares a list of default entries which can be used when
looking for the default configuration (which is used when the main
.config doesn't exists yet.)

- "modules"
This declares the symbol to be used as the MODULES symbol, which
enables the third modular state for all config symbols.
8 changes: 8 additions & 0 deletions Documentation/kbuild/kconfig.rst
Original file line number Diff line number Diff line change
@@ -41,6 +41,14 @@ KCONFIG_CONFIG
This environment variable can be used to specify a default kernel config
file name to override the default name of ".config".

KCONFIG_DEFCONFIG_LIST
----------------------

This environment variable specifies a list of config files which can be used
as a base configuration in case the .config does not exist yet. Entries in
the list are separated with whitespaces to each other, and the first one
that exists is used.

KCONFIG_OVERWRITECONFIG
-----------------------
If you set KCONFIG_OVERWRITECONFIG in the environment, Kconfig will not
9 changes: 0 additions & 9 deletions init/Kconfig
Original file line number Diff line number Diff line change
@@ -1,13 +1,4 @@
# SPDX-License-Identifier: GPL-2.0-only
config DEFCONFIG_LIST
string
depends on !UML
option defconfig_list
default "/lib/modules/$(shell,uname -r)/.config"
default "/etc/kernel-config"
default "/boot/config-$(shell,uname -r)"
default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)"

config CC_VERSION_TEXT
string
default "$(CC_VERSION_TEXT)"
10 changes: 10 additions & 0 deletions scripts/kconfig/Makefile
Original file line number Diff line number Diff line change
@@ -13,6 +13,16 @@ ifeq ($(quiet),silent_)
silent := -s
endif

export KCONFIG_DEFCONFIG_LIST :=
ifneq ($(SRCARCH),um)
kernel-release := $(shell uname -r)
KCONFIG_DEFCONFIG_LIST := \
/lib/modules/$(kernel-release)/.config \
/etc/kernel-config \
/boot/config-$(kernel-release) \
arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)
endif

# We need this, in case the user has it in its environment
unexport CONFIG_

38 changes: 28 additions & 10 deletions scripts/kconfig/confdata.c
Original file line number Diff line number Diff line change
@@ -360,28 +360,46 @@ int conf_read_simple(const char *name, int def)
if (name) {
in = zconf_fopen(name);
} else {
struct property *prop;
char *env;

name = conf_get_configname();
in = zconf_fopen(name);
if (in)
goto load;
sym_add_change_count(1);
if (!sym_defconfig_list)

env = getenv("KCONFIG_DEFCONFIG_LIST");
if (!env)
return 1;

for_all_defaults(sym_defconfig_list, prop) {
if (expr_calc_value(prop->visible.expr) == no ||
prop->expr->type != E_SYMBOL)
continue;
sym_calc_value(prop->expr->left.sym);
name = sym_get_string_value(prop->expr->left.sym);
in = zconf_fopen(name);
while (1) {
bool is_last;

while (isspace(*env))
env++;

if (!*env)
break;

p = env;
while (*p && !isspace(*p))
p++;

is_last = (*p == '\0');

*p = '\0';

in = zconf_fopen(env);
if (in) {
conf_message("using defaults found in %s",
name);
env);
goto load;
}

if (is_last)
break;

env = p + 1;
}
}
if (!in)
1 change: 0 additions & 1 deletion scripts/kconfig/expr.h
Original file line number Diff line number Diff line change
@@ -287,7 +287,6 @@ struct file *lookup_file(const char *name);

extern struct symbol symbol_yes, symbol_no, symbol_mod;
extern struct symbol *modules_sym;
extern struct symbol *sym_defconfig_list;
extern int cdebug;
struct expr *expr_alloc_symbol(struct symbol *sym);
struct expr *expr_alloc_one(enum expr_type type, struct expr *ce);
1 change: 0 additions & 1 deletion scripts/kconfig/lexer.l
Original file line number Diff line number Diff line change
@@ -99,7 +99,6 @@ n [A-Za-z0-9_-]
"def_bool" return T_DEF_BOOL;
"def_tristate" return T_DEF_TRISTATE;
"default" return T_DEFAULT;
"defconfig_list" return T_DEFCONFIG_LIST;
"depends" return T_DEPENDS;
"endchoice" return T_ENDCHOICE;
"endif" return T_ENDIF;
1 change: 0 additions & 1 deletion scripts/kconfig/lkc.h
Original file line number Diff line number Diff line change
@@ -96,7 +96,6 @@ struct property *menu_add_prompt(enum prop_type type, char *prompt, struct expr
void menu_add_expr(enum prop_type type, struct expr *expr, struct expr *dep);
void menu_add_symbol(enum prop_type type, struct symbol *sym, struct expr *dep);
void menu_add_option_modules(void);
void menu_add_option_defconfig_list(void);
void menu_add_option_allnoconfig_y(void);
void menu_finalize(struct menu *parent);
void menu_set_type(int type);
9 changes: 0 additions & 9 deletions scripts/kconfig/menu.c
Original file line number Diff line number Diff line change
@@ -219,15 +219,6 @@ void menu_add_option_modules(void)
modules_sym = current_entry->sym;
}

void menu_add_option_defconfig_list(void)
{
if (!sym_defconfig_list)
sym_defconfig_list = current_entry->sym;
else if (sym_defconfig_list != current_entry->sym)
zconf_error("trying to redefine defconfig symbol");
sym_defconfig_list->flags |= SYMBOL_NO_WRITE;
}

void menu_add_option_allnoconfig_y(void)
{
current_entry->sym->flags |= SYMBOL_ALLNOCONFIG_Y;
6 changes: 0 additions & 6 deletions scripts/kconfig/parser.y
Original file line number Diff line number Diff line change
@@ -53,7 +53,6 @@ static struct menu *current_menu, *current_entry;
%token T_COMMENT
%token T_CONFIG
%token T_DEFAULT
%token T_DEFCONFIG_LIST
%token T_DEF_BOOL
%token T_DEF_TRISTATE
%token T_DEPENDS
@@ -223,11 +222,6 @@ config_option: T_OPTION T_MODULES T_EOL
menu_add_option_modules();
};

config_option: T_OPTION T_DEFCONFIG_LIST T_EOL
{
menu_add_option_defconfig_list();
};

config_option: T_OPTION T_ALLNOCONFIG_Y T_EOL
{
menu_add_option_allnoconfig_y();
1 change: 0 additions & 1 deletion scripts/kconfig/symbol.c
Original file line number Diff line number Diff line change
@@ -35,7 +35,6 @@ static struct symbol symbol_empty = {
.flags = SYMBOL_VALID,
};

struct symbol *sym_defconfig_list;
struct symbol *modules_sym;
static tristate modules_val;

4 changes: 4 additions & 0 deletions scripts/kconfig/tests/conftest.py
Original file line number Diff line number Diff line change
@@ -53,6 +53,10 @@ def _run_conf(self, mode, dot_config=None, out_file='.config',
# Override 'srctree' environment to make the test as the top directory
extra_env['srctree'] = self._test_dir

# Clear KCONFIG_DEFCONFIG_LIST to keep unit tests from being affected
# by the user's environment.
extra_env['KCONFIG_DEFCONFIG_LIST'] = ''

# Run Kconfig in a temporary directory.
# This directory is automatically removed when done.
with tempfile.TemporaryDirectory() as temp_dir:

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