Re: linux-next: build warning after merge of the mm tree

Uwe Kleine-König
2024-03-13T21:11:56Z

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Hello Masahiro,

On Thu, Mar 14, 2024 at 12:22:46AM +0900, Masahiro Yamada wrote:
> On Wed, Mar 13, 2024 at 6:01 PM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> >
> > On Wed, Mar 13, 2024 at 03:07:28PM +1100, Stephen Rothwell wrote:
> > > Hi all,
> > >
> > > After merging the mm tree, today's linux-next build (powerpc allyesconfig)
> > > produced this warning:
> > >
> > > Use of uninitialized value $ENV{"abs_srctree"} in concatenation (.) or string at /home/sfr/next/next/lib/build_OID_registry line 38.
> > >
> > > Introduced by commit
> > >
> > > 325f7b0aaea6 ("lib/build_OID_registry: Don't mention the full path of the script in output")
> > >
> > > from the mm-nonmm-unstable branch of the mm tree.
> >
> > Actually the warning doesn't happen on 325f7b0aaea6. The commit is only
> > problematic in combination with commit
> >
> > e2bad142bb3d ("kbuild: unexport abs_srctree and abs_objtree")
> >
> > . This commit suggests to use $(abspath ) or $(realpath ) instead, but I
> > fail to apply this suggestion here.
> >
> > Obviously
> >
> > diff --git a/Makefile b/Makefile
> > index 5e09b53b4850..f73a73a125e0 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -39,7 +39,7 @@ __all:
> > # prepare rule.
> >
> > this-makefile := $(lastword $(MAKEFILE_LIST))
> > -abs_srctree := $(realpath $(dir $(this-makefile)))
> > +export abs_srctree := $(realpath $(dir $(this-makefile)))
> > abs_objtree := $(CURDIR)
> >
> > ifneq ($(sub_make_done),1)
> >
> > would help.
> >
> > Any ideas how to properly handle that? Would the export be ok?
>
> Oh well, you are making a lot of effort just for a C comment line.

I don't care much either. Given that now I know how to somewhat keep the
originally intended information, the effort between a fixed string and
a dynamically generated one isn't very relevant.

> use Cwd qw(abs_path);
>
> my $abs_srctree = abs_path($ENV{'srctree'});

Ah, I missed that srctree is an exported variable. Thanks, will prepare
a v2. akpm already dropped my initial patch from his queue.

Thanks for your input.

Best regards
Uwe

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