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Diffstat (limited to 'config_host/README.md')
| -rw-r--r-- | config_host/README.md | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/config_host/README.md b/config_host/README.md new file mode 100644 index 000000000000..5dd2d5263481 --- /dev/null +++ b/config_host/README.md @@ -0,0 +1,25 @@ +These are configuration files for various features as detected by configure. + +Include only those files you need (in order to reduce rebuilds when a setting changes). + +Settings here are only C/C++ #define directives, so they apply only to C/C++ source, +not to Makefiles. + + + +Adding a new setting: +===================== + +- do AC_DEFINE(HAVE_FOO) in configure.ac when a setting should be set +- choose the proper config_host/config_XXX.h file to use + - if it is a global setting (such as availability of a compiler feature), + use config_host/config_global.h + - otherwise check if there is a matching config_host/config_XXX.h file + - if none matches, add a new one: + - add config_host/config_XXX.h.in here, with just #ifndef include guard + - add AC_CONFIG_HEADERS([config_host/config_XXX.h]) next to the others + in configure.ac +- add #define HAVE_FOO 0 to the config_host/config_XXX.h , possibly with a comment + (do not use #undef HAVE_FOO, unless the setting has more values than on/off) +- add #include <config_XXX.h> before any #if HAVE_FOO in a source file +- make sure you use #if HAVE_FOO for on/off settings, do not use #ifdef |