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-Copyright 2004 Linus Torvalds
-Copyright 2004 Pavel Machek <pavel@ucw.cz>
-Copyright 2006 Bob Copeland <me@bobcopeland.com>
-
-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" is
-there because sparse will complain about casting to/from a bitwise type,
-but in this case we really _do_ want to force the conversion). And because
-the enum values are all the same type, now "enum pm_request" will be that
-type too.
-
-And with gcc, all the __bitwise/__force stuff goes away, and it all ends
-up looking just like integers to gcc.
-
-Quite frankly, you don't need the enum there. The above all really just
-boils 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 a
-constant zero as a bitwise integer type without sparse ever complaining.
-This is because "bitwise" (as the name implies) was designed for making
-sure that bitwise types don't get mixed up (little-endian vs big-endian
-vs cpu-endian vs whatever), and there the constant "0" really _is_
-special.
-
-__bitwise__ - to be used for relatively compact stuff (gfp_t, etc.) that
-is mostly warning-free and is supposed to stay that way. Warnings will
-be generated without __CHECK_ENDIAN__.
-
-__bitwise - noisy stuff; in particular, __le*/__be* are that. We really
-don't want to drown in noise unless we'd explicitly asked for it.
-
-
-Getting sparse
-~~~~~~~~~~~~~~
-
-You can get latest released versions from the Sparse homepage at
-https://sparse.wiki.kernel.org/index.php/Main_Page
-
-Alternatively, you can get snapshots of the latest development version
-of sparse using git to clone..
-
- git://git.kernel.org/pub/scm/devel/sparse/sparse.git
-
-DaveJ has hourly generated tarballs of the git tree available at..
-
- http://www.codemonkey.org.uk/projects/git-snapshots/sparse/
-
-
-Once you have it, just do
-
- make
- make install
-
-as a regular user, and it will install sparse in your ~/bin directory.
-
-Using sparse
-~~~~~~~~~~~~
-
-Do a kernel make with "make C=1" to run sparse on all the C files that get
-recompiled, or use "make C=2" to run sparse on the files whether they need to
-be recompiled or not. The latter is a fast way to check the whole tree if you
-have already built it.
-
-The optional make variable CF can be used to pass arguments to sparse. The
-build system passes -Wbitwise to sparse automatically. To perform endianness
-checks, you may define __CHECK_ENDIAN__:
-
- make C=2 CF="-D__CHECK_ENDIAN__"
-
-These checks are disabled by default as they generate a host of warnings.