73 lines
2.2 KiB
Plaintext
73 lines
2.2 KiB
Plaintext
|
Copyright 2004 Linus Torvalds
|
||
|
|
Copyright 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" 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.
|
||
|
|
|
||
|
|
Modify top-level Makefile to say
|
||
|
|
|
||
|
|
CHECK = sparse -Wbitwise
|
||
|
|
|
||
|
|
or you don't get any checking at all.
|
||
|
|
|
||
|
|
|
||
|
|
Where to get sparse
|
||
|
|
~~~~~~~~~~~~~~~~~~~
|
||
|
|
|
||
|
|
With BK, you can just get it from
|
||
|
|
|
||
|
|
bk://sparse.bkbits.net/sparse
|
||
|
|
|
||
|
|
and DaveJ has tar-balls at
|
||
|
|
|
||
|
|
http://www.codemonkey.org.uk/projects/bitkeeper/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 the
|
||
|
|
C files that get recompiled, or with "make C=2" will run sparse on the
|
||
|
|
files whether they need to be recompiled or not (ie the latter is fast way
|
||
|
|
to check the whole tree if you have already built it).
|