linux-kernel - Re: [PATCH] kbuild: check arch/$(SRCARCH)/include/generated before out-of-tree build

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Date:   Tue, 9 Jul 2019 21:21:44 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     linux-kbuild <linux-kbuild@...r.kernel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kbuild: check arch/$(SRCARCH)/include/generated before
 out-of-tree build

Hi Geert,

On Tue, Jul 9, 2019 at 5:31 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Yamada-san,
>
> On Sun, Apr 7, 2019 at 12:45 PM Masahiro Yamada
> <yamada.masahiro@...ionext.com> wrote:
> > After cross-compiling the kernel, "make mrproper" should be executed
> > with the proper ARCH= option. Otherwise, stale objects will remain
> > under arch/$(SRCARCH)/.
> >
> > One bad scenario is like this:
> >
> >   $ make ARCH=arm defconfig all   # cross-compile the kernel for arm
> >   $ make mrproper                 # mrproper for host-arch (i.e. x86)
> >   $ make ARCH=arm O=build_dir defconfig all
> >
> > If you miss ARCH= for mrproper and cross-compile the kernel with O=
> > and ARCH= options, Kbuild will happily start to build, but may fail
> > due to stale objects in the srctree.
> >
> > If $(srctree)/arch/$(SRCARCH)/include/generated/ exists, let's stop
> > the out-of-tree build. To detect this, mrproper should clean only
> > arch/$(SRCARCH)/include/generated/.
> >
> > Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> > ---
> >
> >  Makefile | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 10643c3..17945ce 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -1091,7 +1091,9 @@ PHONY += prepare archprepare prepare1 prepare3
> >  prepare3: include/config/kernel.release
> >  ifneq ($(srctree),.)
> >         @$(kecho) '  Using $(srctree) as source for kernel'
> > -       $(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
> > +       $(Q)if [ -f $(srctree)/.config -o \
> > +                -d $(srctree)/include/config -o \
> > +                -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
> >                 echo >&2 "  $(srctree) is not clean, please run 'make mrproper'"; \
> >                 echo >&2 "  in the '$(srctree)' directory.";\
>
> This took me a bit to find out what was wrong...
>
> Usually I don't run "make mrproper", as it removes files I may want to
> keep (e.g. tags).  Hence I ran "git ls-files -o | grep m68k | xargs rm"
> (I usually build in separate output directories), confirmed with "git
> ls-files -o" there were no remaining build artefacts, and was surprised
> to discover I still got the error message above?!?
>
> Apparently arch/m68k/include/generated was still present, but as "git
> ls-files -o" only shows files, not directories, it was not listed.
> Perhaps the directory checks above can be changed to directory exists
> _and_ is not empty?

No.

Since you did not run mrproper,
Kbuild _correctly_ showed error.
This is the expected and correct behavior. :)

The upstream kernel is not a place
to be customized for your workflow. Sorry.


Every developer has a set of handy custom commands.

Since you are already running a long command,
why don't you add one more line, and put in ~/.bash_aliases or somewhere?

my_mrproper()
{
    git ls-files -o | grep m68k | xargs rm
    rm -rf arch/m68k/include/generated
}


-- 
Best Regards
Masahiro Yamada