X-From_: pavel@ucw.cz  Sun Dec 26 08:22:49 2004
Received: from mailin1.pacific.net.au (mailin1.pacific.net.au [61.8.0.80])
	by mangalore.zipworld.com.au (8.12.3/8.12.3/Debian-7.1) with ESMTP id iBPLMnAE028515
	for <akpm@zip.com.au>; Sun, 26 Dec 2004 08:22:49 +1100
Received: from amd.ucw.cz (gprs212-19.eurotel.cz [160.218.212.19])
	by mailin1.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with ESMTP id iBPLMgYo019658
	for <akpm@zip.com.au>; Sun, 26 Dec 2004 08:22:44 +1100
Received: by amd.ucw.cz (Postfix, from userid 8)
	id 5D8EE2C703; Sat, 25 Dec 2004 22:22:35 +0100 (CET)
Date: Sat, 25 Dec 2004 22:22:35 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Andrew Morton <akpm@zip.com.au>,
        kernel list <linux-kernel@vger.kernel.org>
Subject: docs: add sparse howto
Message-ID: <20041225212235.GA20147@elf.ucw.cz>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
X-Warning: Reading this can be dangerous to your mental health.
User-Agent: Mutt/1.5.6+20040722i
X-Spam-Level: 
X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on bix
X-Spam-Status: No, hits=-4.9 required=1.0 tests=BAYES_00 autolearn=ham 
	version=2.60

Hi!

Installing / using sparse is not exactly trivial, this should make
setting it up easier. Please apply, 
								Pavel

Adapted From: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Pavel Machek <pavel@suse.cz>

--- clean/Documentation/sparse.txt	2004-10-16 23:48:08.000000000 +0200
+++ linux/Documentation/sparse.txt	2004-10-24 22:44:47.000000000 +0200
@@ -0,0 +1,72 @@
+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).

-- 
People were complaining that M$ turns users into beta-testers...
...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!