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Kconfig: Introduce the "imply" keyword

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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>
This commit is contained in:
Nicolas Pitre 2016-11-11 00:10:05 -05:00 committed by Thomas Gleixner
parent 4b7e9cf9c8
commit 237e3ad0f1
6 changed files with 108 additions and 19 deletions
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29
Documentation/kbuild/kconfig-language.txt
View File

@ -113,6 +113,34 @@ applicable everywhere (see syntax).
That will limit the usefulness but on the other hand avoid
the illegal configurations all over.
- weak reverse dependencies: "imply" <symbol> ["if" <expr>]
This is similar to "select" as it enforces a lower limit on another
symbol except that the "implied" symbol's value may still be set to n
from a direct dependency or with a visible prompt.
Given the following example:
config FOO
tristate
imply BAZ
config BAZ
tristate
depends on BAR
The following values are possible:
FOO BAR BAZ's default choice for BAZ
--- --- ------------- --------------
n y n N/m/y
m y m M/y/n
y y y Y/n
y n * N
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.
- limiting menu display: "visible if" <expr>
This attribute is only applicable to menu blocks, if the condition is
false, the menu block is not displayed to the user (the symbols
@ -481,6 +509,7 @@ historical issues resolved through these different solutions.
b) Match dependency semantics:
b1) Swap all "select FOO" to "depends on FOO" or,
b2) Swap all "depends on FOO" to "select FOO"
c) Consider the use of "imply" instead of "select"
The resolution to a) can be tested with the sample Kconfig file
Documentation/kbuild/Kconfig.recursion-issue-01 through the removal

2
scripts/kconfig/expr.h
View File

@ -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 */

55
scripts/kconfig/menu.c
View File

@ -233,6 +233,8 @@ static void sym_check_prop(struct symbol *sym)
{
struct property *prop;
struct symbol *sym2;
char *use;
for (prop = sym->prop; prop; prop = prop->next) {
switch (prop->type) {
case P_DEFAULT:
@ -252,18 +254,20 @@ static void sym_check_prop(struct symbol *sym)
}
break;
case P_SELECT:
case P_IMPLY:
use = prop->type == P_SELECT ? "select" : "imply";
sym2 = prop_get_symbol(prop);
if (sym->type != S_BOOLEAN && sym->type != S_TRISTATE)
prop_warn(prop,
"config symbol '%s' uses select, but is "
"not boolean or tristate", sym->name);
"config symbol '%s' uses %s, but is "
"not boolean or tristate", sym->name, use);
else if (sym2->type != S_UNKNOWN &&
sym2->type != S_BOOLEAN &&
sym2->type != S_TRISTATE)
prop_warn(prop,
"'%s' has wrong type. 'select' only "
"'%s' has wrong type. '%s' only "
"accept arguments of boolean and "
"tristate type", sym2->name);
"tristate type", sym2->name, use);
break;
case P_RANGE:
if (sym->type != S_INT && sym->type != S_HEX)
@ -333,6 +337,10 @@ void menu_finalize(struct menu *parent)
struct symbol *es = prop_get_symbol(prop);
es->rev_dep.expr = expr_alloc_or(es->rev_dep.expr,
expr_alloc_and(expr_alloc_symbol(menu->sym), expr_copy(dep)));
} else if (prop->type == P_IMPLY) {
struct symbol *es = prop_get_symbol(prop);
es->implied.expr = expr_alloc_or(es->implied.expr,
expr_alloc_and(expr_alloc_symbol(menu->sym), expr_copy(dep)));
}
}
}
@ -612,13 +620,30 @@ static struct property *get_symbol_prop(struct symbol *sym)
return prop;
}
static void get_symbol_props_str(struct gstr *r, struct symbol *sym,
enum prop_type tok, const char *prefix)
{
bool hit = false;
struct property *prop;
for_all_properties(sym, prop, tok) {
if (!hit) {
str_append(r, prefix);
hit = true;
} else
str_printf(r, " && ");
expr_gstr_print(prop->expr, r);
}
if (hit)
str_append(r, "\n");
}
/*
* head is optional and may be NULL
*/
static void get_symbol_str(struct gstr *r, struct symbol *sym,
struct list_head *head)
{
bool hit;
struct property *prop;
if (sym && sym->name) {
@ -648,22 +673,20 @@ static void get_symbol_str(struct gstr *r, struct symbol *sym,
}
}
hit = false;
for_all_properties(sym, prop, P_SELECT) {
if (!hit) {
str_append(r, " Selects: ");
hit = true;
} else
str_printf(r, " && ");
expr_gstr_print(prop->expr, r);
}
if (hit)
str_append(r, "\n");
get_symbol_props_str(r, sym, P_SELECT, _(" Selects: "));
if (sym->rev_dep.expr) {
str_append(r, _(" Selected by: "));
expr_gstr_print(sym->rev_dep.expr, r);
str_append(r, "\n");
}
get_symbol_props_str(r, sym, P_IMPLY, _(" Implies: "));
if (sym->implied.expr) {
str_append(r, _(" Implied by: "));
expr_gstr_print(sym->implied.expr, r);
str_append(r, "\n");
}
str_append(r, "\n\n");
}

24
scripts/kconfig/symbol.c
View File

@ -258,6 +258,15 @@ static void sym_calc_visibility(struct symbol *sym)
sym->rev_dep.tri = tri;
sym_set_changed(sym);
}
tri = no;
if (sym->implied.expr && sym->dir_dep.tri != no)
tri = expr_calc_value(sym->implied.expr);
if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
tri = yes;
if (sym->implied.tri != tri) {
sym->implied.tri = tri;
sym_set_changed(sym);
}
}
/*
@ -397,6 +406,10 @@ void sym_calc_value(struct symbol *sym)
newval.tri = EXPR_AND(expr_calc_value(prop->expr),
prop->visible.tri);
}
if (sym->implied.tri != no) {
sym->flags |= SYMBOL_WRITE;
newval.tri = EXPR_OR(newval.tri, sym->implied.tri);
}
}
calc_newval:
if (sym->dir_dep.tri == no && sym->rev_dep.tri != no) {
@ -413,7 +426,8 @@ void sym_calc_value(struct symbol *sym)
}
newval.tri = EXPR_OR(newval.tri, sym->rev_dep.tri);
}
if (newval.tri == mod && sym_get_type(sym) == S_BOOLEAN)
if (newval.tri == mod &&
(sym_get_type(sym) == S_BOOLEAN || sym->implied.tri == yes))
newval.tri = yes;
break;
case S_STRING:
@ -498,6 +512,8 @@ bool sym_tristate_within_range(struct symbol *sym, tristate val)
return false;
if (sym->visible <= sym->rev_dep.tri)
return false;
if (sym->implied.tri == yes && val == mod)
return false;
if (sym_is_choice_value(sym) && sym->visible == yes)
return val == yes;
return val >= sym->rev_dep.tri && val <= sym->visible;
@ -750,6 +766,10 @@ const char *sym_get_string_default(struct symbol *sym)
if (sym->type == S_BOOLEAN && val == mod)
val = yes;
/* adjust the default value if this symbol is implied by another */
if (val < sym->implied.tri)
val = sym->implied.tri;
switch (sym->type) {
case S_BOOLEAN:
case S_TRISTATE:
@ -1352,6 +1372,8 @@ const char *prop_get_type_name(enum prop_type type)
return "choice";
case P_SELECT:
return "select";
case P_IMPLY:
return "imply";
case P_RANGE:
return "range";
case P_SYMBOL:

1
scripts/kconfig/zconf.gperf
View File

@ -38,6 +38,7 @@ 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

16
scripts/kconfig/zconf.y
View File

@ -31,7 +31,7 @@ struct symbol *symbol_hash[SYMBOL_HASHSIZE];
static struct menu *current_menu, *current_entry;
%}
%expect 30
%expect 32
%union
{
@ -62,6 +62,7 @@ static struct menu *current_menu, *current_entry;
%token <id>T_TYPE
%token <id>T_DEFAULT
%token <id>T_SELECT
%token <id>T_IMPLY
%token <id>T_RANGE
%token <id>T_VISIBLE
%token <id>T_OPTION
@ -124,7 +125,7 @@ stmt_list:
;
option_name:
T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_OPTIONAL | T_RANGE | T_DEFAULT | T_VISIBLE
T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_IMPLY | T_OPTIONAL | T_RANGE | T_DEFAULT | T_VISIBLE
;
common_stmt:
@ -216,6 +217,12 @@ config_option: T_SELECT T_WORD if_expr T_EOL
printd(DEBUG_PARSE, "%s:%d:select\n", zconf_curname(), zconf_lineno());
};
config_option: T_IMPLY T_WORD if_expr T_EOL
{
menu_add_symbol(P_IMPLY, sym_lookup($2, 0), $3);
printd(DEBUG_PARSE, "%s:%d:imply\n", zconf_curname(), zconf_lineno());
};
config_option: T_RANGE symbol symbol if_expr T_EOL
{
menu_add_expr(P_RANGE, expr_alloc_comp(E_RANGE,$2, $3), $4);
@ -664,6 +671,11 @@ static void print_symbol(FILE *out, struct menu *menu)
expr_fprint(prop->expr, out);
fputc('\n', out);
break;
case P_IMPLY:
fputs( " imply ", out);
expr_fprint(prop->expr, out);
fputc('\n', out);
break;
case P_RANGE:
fputs( " range ", out);
expr_fprint(prop->expr, out);