| From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
| From: Will McVicker <willmcvicker@google.com> |
| Date: Tue, 7 Dec 2021 09:41:37 -0800 |
| Subject: ANDROID: kbuild: add support for compiling external device trees |
| |
| Similar to external modules, the device tree should also be allowed to |
| be compiled using out-of-tree source. This would allow one to further |
| separate the core kernel from the vendor-specific device trees. To do |
| this, we just need to allow the user to set the "dtstree" and |
| "DTC_INCLUDE" build properties in the build environment. |
| |
| To setup the external device tree, you can follow these steps: |
| |
| 1) Move the device tree to your out-of-tree project. |
| 2) Move the dt-bindings to your out-of-tree project. |
| 3) Configure your build environment to set the following variables: |
| |
| dtstree=/path/to/device/tree |
| DTC_INCLUDE=/path/to/device/tree/dtc/include-prefixes |
| |
| If you are using build.sh, then you can use DTS_EXT_DIR to define the |
| dtstree. |
| |
| Bug: 210036798 |
| Signed-off-by: Will McVicker <willmcvicker@google.com> |
| Change-Id: Ibf05544ee8250a68b882328817a267518ae478b5 |
| Signed-off-by: Lee Jones <joneslee@google.com> |
| --- |
| Makefile | 8 ++++++-- |
| scripts/Makefile.lib | 4 +++- |
| 2 files changed, 9 insertions(+), 3 deletions(-) |
| |
| diff --git a/Makefile b/Makefile |
| --- a/Makefile |
| +++ b/Makefile |
| @@ -1478,7 +1478,9 @@ kselftest-merge: |
| # Devicetree files |
| |
| ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),) |
| -dtstree := arch/$(SRCARCH)/boot/dts |
| +# ANDROID: allow this to be overridden by the build environment. This allows |
| +# one to compile a device tree that is located out-of-tree. |
| +dtstree ?= arch/$(SRCARCH)/boot/dts |
| endif |
| |
| ifneq ($(dtstree),) |
| @@ -2035,7 +2037,9 @@ $(clean-dirs): |
| |
| clean: $(clean-dirs) |
| $(call cmd,rmfiles) |
| - @find $(or $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \ |
| + @find $(or $(KBUILD_EXTMOD), .) \ |
| + $(if $(filter-out arch/$(SRCARCH)/boot/dts, $(dtstree)), $(dtstree)) \ |
| + $(RCS_FIND_IGNORE) \ |
| \( -name '*.[aios]' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \ |
| -o -name '*.ko.*' \ |
| -o -name '*.dtb' -o -name '*.dtbo' \ |
| diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib |
| --- a/scripts/Makefile.lib |
| +++ b/scripts/Makefile.lib |
| @@ -242,7 +242,9 @@ cpp_flags = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \ |
| |
| ld_flags = $(KBUILD_LDFLAGS) $(ldflags-y) $(LDFLAGS_$(@F)) |
| |
| -DTC_INCLUDE := $(srctree)/scripts/dtc/include-prefixes |
| +# ANDROID: Allow DTC_INCLUDE to be set by the BUILD_CONFIG. This allows one to |
| +# compile an out-of-tree device tree. |
| +DTC_INCLUDE += $(srctree)/scripts/dtc/include-prefixes |
| |
| dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \ |
| $(addprefix -I,$(DTC_INCLUDE)) \ |
