diff options
Diffstat (limited to 'extra/config/kconfig-language.txt')
| -rw-r--r-- | extra/config/kconfig-language.txt | 62 |
1 files changed, 25 insertions, 37 deletions
diff --git a/extra/config/kconfig-language.txt b/extra/config/kconfig-language.txt index 649cb8799..c858f8419 100644 --- a/extra/config/kconfig-language.txt +++ b/extra/config/kconfig-language.txt @@ -104,14 +104,21 @@ applicable everywhere (see syntax). Reverse dependencies can only be used with boolean or tristate symbols. Note: - select is evil.... select will by brute force set a symbol - equal to 'y' without visiting the dependencies. So abusing - select you are able to select a symbol FOO even if FOO depends - on BAR that is not set. In general use select only for - non-visible symbols (no prompts anywhere) and for symbols with - no dependencies. That will limit the usefulness but on the - other hand avoid the illegal configurations all over. kconfig - should one day warn about such things. + select should be used with care. select will force + a symbol to a value without visiting the dependencies. + By abusing select you are able to select a symbol FOO even + if FOO depends on BAR that is not set. + In general use select only for non-visible symbols + (no prompts anywhere) and for symbols with no dependencies. + That will limit the usefulness but on the other hand avoid + the illegal configurations all over. + +- 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 + contained there can still be selected by other symbols, though). It is + similar to a conditional "prompt" attribute for individual menu + entries. Default value of "visible" is true. - numerical ranges: "range" <symbol> <symbol> ["if" <expr>] This allows to limit the range of possible input values for int @@ -180,7 +187,7 @@ Expressions are listed in decreasing order of precedence. (7) 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 it's +respectively for calculations). A menu entry becomes visible when its expression evaluates to 'm' or 'y'. There are two types of symbols: constant and non-constant symbols. @@ -267,7 +274,7 @@ separate list of options. choices: - "choice" + "choice" [symbol] <choice options> <choice block> "endchoice" @@ -281,6 +288,10 @@ 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. +If no [symbol] is associated with a choice, then you can not have multiple +definitions of that choice. If a [symbol] is associated to the choice, +then you may define the same choice (ie. with the same entries) in another +place. comment: @@ -299,7 +310,8 @@ menu: "endmenu" This defines a menu block, see "Menu structure" above for more -information. The only possible options are dependencies. +information. The only possible options are dependencies and "visible" +attributes. if: @@ -321,7 +333,8 @@ mainmenu: "mainmenu" <prompt> This sets the config program's title bar if the config program chooses -to use it. +to use it. It should be placed at the top of the configuration, before any +other statement. Kconfig hints @@ -375,28 +388,3 @@ config FOO depends on BAR && m limits FOO to module (=m) or disabled (=n). - - -Build limited by a third config symbol which may be =y or =m -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -A common idiom that we see (and sometimes have problems with) is this: - -When option C in B (module or subsystem) uses interfaces from A (module -or subsystem), and both A and B are tristate (could be =y or =m if they -were independent of each other, but they aren't), then we need to limit -C such that it cannot be built statically if A is built as a loadable -module. (C already depends on B, so there is no dependency issue to -take care of here.) - -If A is linked statically into the kernel image, C can be built -statically or as loadable module(s). However, if A is built as loadable -module(s), then C must be restricted to loadable module(s) also. This -can be expressed in kconfig language as: - -config C - depends on A = y || A = B - -or for real examples, use this command in a kernel tree: - -$ find . -name Kconfig\* | xargs grep -ns "depends on.*=.*||.*=" | grep -v orig - |