From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- Documentation/sparse.txt | 72 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 Documentation/sparse.txt (limited to 'Documentation/sparse.txt') diff --git a/Documentation/sparse.txt b/Documentation/sparse.txt new file mode 100644 index 000000000000..f97841478459 --- /dev/null +++ b/Documentation/sparse.txt @@ -0,0 +1,72 @@ +Copyright 2004 Linus Torvalds +Copyright 2004 Pavel Machek + +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). -- cgit v1.2.3