Messages in this thread | | | Date | Tue, 21 Dec 2004 13:15:09 +0000 | From | Paulo Marques <> | Subject | Re: swsusp bigdiff [was Re: [PATCH] Software Suspend split to two stage V2.] |
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Pavel Machek wrote: > [...] > --- 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). > --- clean/Makefile 2004-10-19 14:16:26.000000000 +0200 > +++ linux/Makefile 2004-10-29 11:56:48.000000000 +0200 > @@ -325,7 +325,7 @@ > DEPMOD = /sbin/depmod > KALLSYMS = scripts/kallsyms > PERL = perl > -CHECK = sparse > +CHECK = sparse -Wbitwise
I know this is a "big diff" patch, but it seems that these sparse changes are completely unrelated to software suspend.
-- Paulo Marques - www.grupopie.com
"A journey of a thousand miles begins with a single step." Lao-tzu, The Way of Lao-tzu
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