Re: kbuild 2.5 is ready for inclusion in the 2.5 kernel

[Gerd Knorr <kraxel@bytesex.org>]

Keith Owens wrote:
>  On 3 May 2002 10:06:04 GMT, 
>  Gerd Knorr <kraxel@bytesex.org> wrote:
> >>  Do it with NO_MAKEFILE_GEN=1 for much, much! faster builds.
> >
> >What exactly is the reason for this hack, i.e. why kbuild wants to
> >rebuild the Makefiles every time?  Isn't it enougth to do that only
> >if .config has been touched?
>  
>  Or any of the Makefile.in files have changed.

.config + all Makefile.in's is still a small number of files where
make has to check the timestamp to see whenever a rebuild of the global
makefile is needed.

>  Or any of the command line options have changed.

Which command line options?

>  Or various environment variables have changed.
>  Or the compiler has changed.

Which environment variables?  CC / CFLAGS?  Well, with other CFLAGS
and/or compiler you have to do a full rebuild anyway, thus using "make
clean" would work equally well ...

>  Or a target file has been altered outside kbuild control.

Which is the users fault IMO.  I don't see the point in trying to catch
this and make kbuild idiot proof.  I doubt it is possible to make kbuild
clever enougth to handle all evil things a user could do.  AI isn't that
good.

>  Coding a special case to work out if the existing global makefile can
>  be reused is horribly error prone.

Special case?  I'd say it is the common case when doing kernel
development.  At least I don't use another compiler for every second
make.  I usually hack some piece of code and recompile the module then.

  Gerd

-- 
You can't please everybody.  And usually if you _try_ to please
everybody, the end result is one big mess.
				-- Linus Torvalds, 2002-04-20