Copyright 2004 Linus TorvaldsCopyright 2004 Pavel Machek <pavel@suse.cz> Using sparse for typechecking~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "__bitwise" is a type attribute, so you have to do something like this:         typedef int __bitwise pm_request_t;         enum pm_request {                PM_SUSPEND = (__force pm_request_t) 1,                PM_RESUME = (__force pm_request_t) 2        }; which makes PM_SUSPEND and PM_RESUME "bitwise" integers (the "__force" isthere because sparse will complain about casting to/from a bitwise type,but in this case we really _do_ want to force the conversion). And becausethe enum values are all the same type, now "enum pm_request" will be thattype too. And with gcc, all the __bitwise/__force stuff goes away, and it all endsup looking just like integers to gcc. Quite frankly, you don't need the enum there. The above all really justboils down to one special "int __bitwise" type. So the simpler way is to just do         typedef int __bitwise pm_request_t;         #define PM_SUSPEND ((__force pm_request_t) 1)        #define PM_RESUME ((__force pm_request_t) 2) and you now have all the infrastructure needed for strict typechecking. One small note: the constant integer "0" is special. You can use aconstant zero as a bitwise integer type without sparse ever complaining.This is because "bitwise" (as the name implies) was designed for makingsure that bitwise types don't get mixed up (little-endian vs big-endianvs cpu-endian vs whatever), and there the constant "0" really _is_special. Use 	make C=[12] CF=-Wbitwise or you don't get any checking at all.  Where to get sparse~~~~~~~~~~~~~~~~~~~ With git, you can just get it from         rsync://rsync.kernel.org/pub/scm/devel/sparse/sparse.git and DaveJ has tar-balls at 	http://www.codemonkey.org.uk/projects/git-snapshots/sparse/  Once you have it, just do         make        make install as your regular user, and it will install sparse in your ~/bin directory.After that, doing a kernel make with "make C=1" will run sparse on all theC files that get recompiled, or with "make C=2" will run sparse on thefiles whether they need to be recompiled or not (ie the latter is fast wayto check the whole tree if you have already built it).