diff options
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/kconfig-language.txt | 9 | ||||
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 14 |
2 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt index 536d5bfbdb8d..fe8b0c4892cf 100644 --- a/Documentation/kbuild/kconfig-language.txt +++ b/Documentation/kbuild/kconfig-language.txt @@ -98,6 +98,15 @@ applicable everywhere (see syntax). times, the limit is set to the largest selection. 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 promts 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. - numerical ranges: "range" <symbol> <symbol> ["if" <expr>] This allows to limit the range of possible input values for int diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index bb5306e9a5c3..e08ef8759a07 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -501,6 +501,20 @@ more details, with real examples. The third parameter may be a text as in this example, but it may also be an expanded variable or a macro. + cc-fullversion + cc-fullversion is useful when the exact version of gcc is needed. + One typical use-case is when a specific GCC version is broken. + cc-fullversion points out a more specific version than cc-version does. + + Example: + #arch/powerpc/Makefile + $(Q)if test "$(call cc-fullversion)" = "040200" ; then \ + echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \ + false ; \ + fi + + In this example for a specific GCC version the build will error out explaining + to the user why it stops. === 4 Host Program support |