On Sun, Sep 9, 2018 at 6:28 PM Masahiro Yamada
[off-list ref] wrote:

2018-09-06 8:53 GMT+09:00 Rob Herring [off-list ref]:

quoted

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 <redacted>
Cc: Michal Marek <redacted>
Cc: Vineet Gupta <redacted>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <redacted>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <redacted>
Cc: Paul Burton <redacted>
Cc: James Hogan <jhogan@kernel.org>
Cc: Ley Foon Tan <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-mips@linux-mips.org
Cc: nios2-dev@lists.rocketboards.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: Rob Herring <robh@kernel.org>
---
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

 Makefile                          | 32 +++++++++++++++++++++++++++++++
 arch/arc/Makefile                 |  6 ------
 arch/arm/Makefile                 | 20 +------------------
 arch/arm64/Makefile               | 17 +---------------
 arch/c6x/Makefile                 |  2 --
 arch/h8300/Makefile               | 11 +----------
 arch/microblaze/Makefile          |  4 +---
 arch/microblaze/boot/dts/Makefile |  2 ++
 arch/mips/Makefile                | 15 +--------------
 arch/nds32/Makefile               |  2 +-
 arch/nios2/Makefile               |  7 -------
 arch/nios2/boot/Makefile          |  4 ----
 arch/powerpc/Makefile             |  3 ---
 arch/xtensa/Makefile              | 12 +-----------
 scripts/Makefile.lib              |  2 +-
 15 files changed, 42 insertions(+), 97 deletions(-)

diff --git a/Makefile b/Makefile
index 2b458801ba74..bc18dbbc16c5 100644
--- a/Makefile
+++ b/Makefile

@@ -1212,6 +1212,32 @@ kselftest-merge:
                $(srctree)/tools/testing/selftests/*/config
        +$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig

+# ---------------------------------------------------------------------------
+# Devicetree files
+
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
+dtstree := arch/$(SRCARCH)/boot/dts
+endif
+
+ifdef CONFIG_OF_EARLY_FLATTREE
+
+%.dtb %.dtb.S %.dtb.o: | dtc
+       $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@

Hmm, I was worried about '%.dtb.o: | dtc'
but seems working.

Compiling %.S -> %.o requires objtool for x86,
but x86 does not support DT.

Well, x86 does support DT to some extent. There's 2 platforms and the
DT unittests build and run on x86.

Actually, we can remove "%.dtb.S %.dtb.o" because we don't need those
as top-level build targets. Must have been a copy-n-paste relic from
before having common rules.

If CONFIG_MODVERSIONS=y, scripts/genksyms/genksyms is required,
%.dtb.S does not contain EXPORT_SYMBOL.

Okay, but that shouldn't affect any of this. We only build *.dtb.S
when doing built-in dtbs.

BTW, 'dtc' should be a PHONY target.

Right, I found that too.

Rob