Re: [PATCH v2 6/9] kbuild: consolidate Devicetree dtb build rules

[Rob Herring]

On Fri, Sep 7, 2018 at 5:33 AM Masahiro Yamada
<yamada.masahiro@xxxxxxxxxxxxx> wrote:
>
> 2018-09-06 8:53 GMT+09:00 Rob Herring <robh@xxxxxxxxxx>:
> > There is nothing arch specific about building dtb files other than their
> > location under /arch/*/boot/dts/. Keeping each arch aligned is a pain.
> > The dependencies and supported targets are all slightly different.
> > Also, a cross-compiler for each arch is needed, but really the host
> > compiler preprocessor is perfectly fine for building dtbs. Move the
> > build rules to a common location and remove the arch specific ones. This
> > is done in a single step to avoid warnings about overriding rules.
> >
> > The build dependencies had been a mixture of 'scripts' and/or 'prepare'.
> > These pull in several dependencies some of which need a target compiler
> > (specifically devicetable-offsets.h) and aren't needed to build dtbs.
> > All that is really needed is dtc, so adjust the dependencies to only be
> > dtc.
> >
> > This change enables support 'dtbs_install' on some arches which were
> > missing the target.
> >
> > Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> > Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
> > Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> > Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Cc: Will Deacon <will.deacon@xxxxxxx>
> > Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Michal Simek <monstr@xxxxxxxxx>
> > Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> > Cc: Paul Burton <paul.burton@xxxxxxxx>
> > Cc: James Hogan <jhogan@xxxxxxxxxx>
> > Cc: Ley Foon Tan <lftan@xxxxxxxxxx>
> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Paul Mackerras <paulus@xxxxxxxxx>
> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Cc: Chris Zankel <chris@xxxxxxxxxx>
> > Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
> > Cc: linux-kbuild@xxxxxxxxxxxxxxx
> > Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx
> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > Cc: uclinux-h8-devel@xxxxxxxxxxxxxxxxxxxx
> > Cc: linux-mips@xxxxxxxxxxxxxx
> > Cc: nios2-dev@xxxxxxxxxxxxxxxxxxxxxx
> > Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> > Cc: linux-xtensa@xxxxxxxxxxxxxxxx
> > Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
> > ---
> > Please ack so I can take the whole series via the DT tree.
> >
> > v2:
> >  - Fix $arch/boot/dts path check for out of tree builds
> >  - Fix dtc dependency for building built-in dtbs
> >  - Fix microblaze built-in dtb building
>
>
> This breaks parallel building
> because two threads could descend into scripts/dtc
> at the same time.
>
> 'all' depends on both 'scripts' and 'dtc'.
>
> * 'scripts' target -- descends into scripts/, then scripts/dtc
> * 'dtc' target     -- descents into scripts/dtc directly

Any suggestions for how to fix given the problem with depending on
scripts? I suppose I could make scripts depend on dtc instead, but I'd
be back to needing to fix cleaning. Or I could just skip removing the
cross compiler dependency for now.

Rob