-Copyright 2004 Linus Torvalds
-Copyright 2004 Pavel Machek <pavel@ucw.cz>
-Copyright 2006 Bob Copeland <me@bobcopeland.com>
+.. Copyright 2004 Linus Torvalds
+.. Copyright 2004 Pavel Machek <pavel@ucw.cz>
+.. Copyright 2006 Bob Copeland <me@bobcopeland.com>
+
+Sparse
+======
+
+Sparse is a semantic checker for C programs; it can be used to find a
+number of potential problems with kernel code. See
+https://lwn.net/Articles/689907/ for an overview of sparse; this document
+contains some kernel-specific sparse information.
+
Using sparse for typechecking
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-----------------------------
-"__bitwise" is a type attribute, so you have to do something like this:
+"__bitwise" is a type attribute, so you have to do something like this::
typedef int __bitwise pm_request_t;
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.
+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
+So the simpler way is to just do::
typedef int __bitwise pm_request_t;
don't want to drown in noise unless we'd explicitly asked for it.
Using sparse for lock checking
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+------------------------------
The following macros are undefined for gcc and defined during a sparse
run to use the "context" tracking feature of sparse, applied to
sparse would otherwise report a context imbalance.
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..
+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..
+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
+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
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__:
+checks, you may define __CHECK_ENDIAN__::
make C=2 CF="-D__CHECK_ENDIAN__"