2018-09-13 11:51 GMT-04:00 Geert Uytterhoeven [off-list ref]:

Hi Yamada-san,

On Wed, Sep 12, 2018 at 3:02 AM Masahiro Yamada
[off-list ref] wrote:

quoted

2018-09-12 0:40 GMT+09:00 Rob Herring [off-list ref]:

quoted

On Mon, Sep 10, 2018 at 10:04 AM Rob Herring [off-list ref] wrote:

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.

[...]

quoted

@@ -1215,6 +1215,33 @@ 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

This can be true when dtstree is unset. So this line should be this
instead to fix the 0-day reported error:

ifneq ($(dtstree),)

quoted

+
+%.dtb : scripts_dtc
+       $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
+
+PHONY += dtbs dtbs_install
+dtbs: scripts_dtc
+       $(Q)$(MAKE) $(build)=$(dtstree)
+
+dtbs_install: dtbs
+       $(Q)$(MAKE) $(dtbinst)=$(dtstree)
+
+all: dtbs
+
+endif

Ah, right.
Even x86 can enable OF and OF_UNITTEST.



Another solution might be,
guard it by 'depends on ARCH_SUPPORTS_OF'.



This is actually what ACPI does.

menuconfig ACPI
        bool "ACPI (Advanced Configuration and Power Interface) Support"
        depends on ARCH_SUPPORTS_ACPI
         ...

ACPI is a real platform feature, as it depends on firmware.

CONFIG_OF can be enabled, and DT overlays can be loaded, on any platform,
even if it has ACPI ;-)

OK, understood.

Thanks!



-- 
Best Regards
Masahiro Yamada