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authorNicolas Pitre <nicolas.pitre@linaro.org>2017-11-16 20:06:39 -0500
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-01-06 02:31:23 +0900
commit9059a3493efea6492451430c7e2fa0af799a2abb (patch)
treebc3011bb806742c6b1f2f4d8b13692aebb51a844 /Documentation/kbuild
parentcfe17c9bbe6a673fdafdab179c32b355ed447f66 (diff)
downloadlinux-9059a3493efea6492451430c7e2fa0af799a2abb.tar.bz2
kconfig: fix relational operators for bool and tristate symbols
Since commit 31847b67bec0 ("kconfig: allow use of relations other than (in)equality") it is possible to use relational operators in Kconfig statements. However, those operators give unexpected results when applied to bool/tristate values: (n < y) = y (correct) (m < y) = y (correct) (n < m) = n (wrong) This happens because relational operators process bool and tristate symbols as strings and m sorts before n. It makes little sense to do a lexicographical compare on bool and tristate values though. Documentation/kbuild/kconfig-language.txt states that expression can have a value of 'n', 'm' or 'y' (or 0, 1, 2 respectively for calculations). Let's make it so for relational comparisons with bool/tristate expressions as well and document them. If at least one symbol is an actual string then the lexicographical compare works just as before. Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'Documentation/kbuild')
-rw-r--r--Documentation/kbuild/kconfig-language.txt23
1 files changed, 15 insertions, 8 deletions
diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index 262722d8867b..c4a293a03c33 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -200,10 +200,14 @@ module state. Dependency expressions have the following syntax:
<expr> ::= <symbol> (1)
<symbol> '=' <symbol> (2)
<symbol> '!=' <symbol> (3)
- '(' <expr> ')' (4)
- '!' <expr> (5)
- <expr> '&&' <expr> (6)
- <expr> '||' <expr> (7)
+ <symbol1> '<' <symbol2> (4)
+ <symbol1> '>' <symbol2> (4)
+ <symbol1> '<=' <symbol2> (4)
+ <symbol1> '>=' <symbol2> (4)
+ '(' <expr> ')' (5)
+ '!' <expr> (6)
+ <expr> '&&' <expr> (7)
+ <expr> '||' <expr> (8)
Expressions are listed in decreasing order of precedence.
@@ -214,10 +218,13 @@ Expressions are listed in decreasing order of precedence.
otherwise 'n'.
(3) If the values of both symbols are equal, it returns 'n',
otherwise 'y'.
-(4) Returns the value of the expression. Used to override precedence.
-(5) Returns the result of (2-/expr/).
-(6) Returns the result of min(/expr/, /expr/).
-(7) Returns the result of max(/expr/, /expr/).
+(4) If value of <symbol1> is respectively lower, greater, lower-or-equal,
+ or greater-or-equal than value of <symbol2>, it returns 'y',
+ otherwise 'n'.
+(5) Returns the value of the expression. Used to override precedence.
+(6) Returns the result of (2-/expr/).
+(7) Returns the result of min(/expr/, /expr/).
+(8) Returns the result of max(/expr/, /expr/).
An expression can have a value of 'n', 'm' or 'y' (or 0, 1, 2
respectively for calculations). A menu entry becomes visible when its