Re: [PATCH] cleanup KERNEL_VERSION definition and linux/version.h

Mike Fedyk (mfedyk@matchmail.com)
Fri, 5 Apr 2002 09:55:27 -0800


> >On Thu, Apr 04, 2002 at 11:36:06AM +1000, Keith Owens wrote:
> >> No, but version.h is working at the moment in 2.4. Why change it?
> >

> On Thu, 4 Apr 2002 18:07:52 -0800,
> Mike Fedyk <mfedyk@matchmail.com> wrote:
> >Why do so many drivers enable options depending on the kernel version?
> >Shouldn't that be stripped out before a patch is accepted into the kernel?
>

On Fri, Apr 05, 2002 at 12:42:39PM +1000, Keith Owens wrote:
> >From kbuild 2.5 top level Makefile.
>
> # FIXME: Current kernel source includes linux/version.h, mainly to get
> # KERNEL_VERSION(). version.h also includes UTS_RELEASE which changes every
> # time the kernel identifiers change. The presence of UTS_RELEASE in version.h
> # causes lots of unnecessary recompilations, very few places actually want
> # UTS_RELEASE. The new makefile generates separate linux/version.h and
> # linux/uts_release.h, with version.h including utsname.h to avoid compilation
> # errors. Find all the source code that needs just UTS_RELEASE and change it to
> # include uts_release.h, then remove #include <linux/uts_release.h> from the
> # commands below. KAO
>
> Unfortunately this area of kbuild 2.4 is fragile. At the moment,
> changes to the top level Makefile indirectly force a rebuild,
> Makefile -> version.h -> KERNEL_VERSION() -> almost everything.
>
> Breaking that chain _might_ cause problems in 2.4 because it does not
> have a complete dependency chain to pick up changes to the top level
> Makefile, it only works at the moment due to the extra recompiles. I
> am not willing to change this in 2.4 until I have got it stable in 2.5.

Sounds like a good plan to work on 2.5 first.

Hmm. It looks like kbuild 2.5 might be able to be split up into a few
separate parts. Do you think so too?

Do you know where I could find some good documentation on Makefiles?
Especially on dependencies and etc?
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