[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v5 1/8] Kconfig: import kconfig.h from Linux 4.3
On 2016/1/24 2:42, Andrew Cooper wrote: > On 23/01/16 17:14, Jonathan Creekmore wrote: >> Shannon Zhao writes: >> >>> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >>> >>> To support using CONFIG_ options in C/CPP expressions, import kconfig.h >>> from the Linux v4.3 tag (commit id >>> 6a13feb9c82803e2b815eca72fa7a9f5561d7861). >>> >>> CC: Doug Goldstein <cardoe@xxxxxxxxxx> >>> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >>> --- >>> xen/include/xen/config.h | 2 +- >>> xen/include/xen/kconfig.h | 54 >>> +++++++++++++++++++++++++++++++++++++++++++++++ >>> 2 files changed, 55 insertions(+), 1 deletion(-) >>> create mode 100644 xen/include/xen/kconfig.h >>> >>> diff --git a/xen/include/xen/config.h b/xen/include/xen/config.h >>> index 7595599..eeb49db 100644 >>> --- a/xen/include/xen/config.h >>> +++ b/xen/include/xen/config.h >>> @@ -7,7 +7,7 @@ >>> #ifndef __XEN_CONFIG_H__ >>> #define __XEN_CONFIG_H__ >>> >>> -#include <generated/autoconf.h> >>> +#include <xen/kconfig.h> >>> >>> #ifndef __ASSEMBLY__ >>> #include <xen/compiler.h> >>> diff --git a/xen/include/xen/kconfig.h b/xen/include/xen/kconfig.h >>> new file mode 100644 >>> index 0000000..d68a7ed >>> --- /dev/null >>> +++ b/xen/include/xen/kconfig.h >>> @@ -0,0 +1,54 @@ >>> +#ifndef __XEN_KCONFIG_H >>> +#define __XEN_KCONFIG_H >>> + >>> +#include <generated/autoconf.h> >>> + >>> +/* >>> + * Helper macros to use CONFIG_ options in C/CPP expressions. Note that >>> + * these only work with boolean and tristate options. >>> + */ >>> + >>> +/* >>> + * Getting something that works in C and CPP for an arg that may or may >>> + * not be defined is tricky. Here, if we have "#define CONFIG_BOOGER 1" >>> + * we match on the placeholder define, insert the "0," for arg1 and >>> generate >>> + * the triplet (0, 1, 0). Then the last step cherry picks the 2nd arg (a >>> one). >>> + * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and >>> when >>> + * the last step cherry picks the 2nd arg, we get a zero. >>> + */ >>> +#define __ARG_PLACEHOLDER_1 0, >>> +#define config_enabled(cfg) _config_enabled(cfg) >>> +#define _config_enabled(value) __config_enabled(__ARG_PLACEHOLDER_##value) >>> +#define __config_enabled(arg1_or_junk) ___config_enabled(arg1_or_junk 1, 0) >>> +#define ___config_enabled(__ignored, val, ...) val >>> + >>> +/* >>> + * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0 >>> + * otherwise. For boolean options, this is equivalent to >>> + * IS_ENABLED(CONFIG_FOO). >>> + */ >>> +#define IS_BUILTIN(option) config_enabled(option) >>> + >>> +/* >>> + * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0 >>> + * otherwise. >>> + */ >>> +#define IS_MODULE(option) config_enabled(option##_MODULE) >>> + >>> +/* >>> + * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled >>> + * code can call a function defined in code compiled based on CONFIG_FOO. >>> + * This is similar to IS_ENABLED(), but returns false when invoked from >>> + * built-in code when CONFIG_FOO is set to 'm'. >>> + */ >>> +#define IS_REACHABLE(option) (config_enabled(option) || \ >>> + (config_enabled(option##_MODULE) && config_enabled(MODULE))) >>> + >>> +/* >>> + * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or >>> 'm', >>> + * 0 otherwise. >>> + */ >>> +#define IS_ENABLED(option) \ >>> + (IS_BUILTIN(option) || IS_MODULE(option)) >>> + >>> +#endif /* __XEN_KCONFIG_H */ >> I am not sure that the complexity of this file is necessary since Xen >> does not support loadable modules. Essentially, IS_ENABLED(CONFIG_FOO) >> is as simple as #ifdef CONFIG_FOO. > > I would like to be able to convert some of our "#ifdef CONFIG_FOO" code > into "if ( IS_ENABLED(CONFIG_FOO) )" to reduce the quantity of code-rot > in often-disabled options. > > However, I agree that we don't want all the module complexity. i.e. > IS_ENABLED() is the only one of these we need. > Oh, yes. Will drop other macros. Thanks, -- Shannon _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |