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kbuild: centralize .dts->.dtb rule

All architectures that use cmd_dtc do so in almost the same way. Create
a central build rule to avoid duplication. The one difference is that
most current uses of dtc build $(obj)/%.dtb from $(src)/dts/%.dts rather
than building the .dtb in the same directory as the .dts file. This
difference will be eliminated arch-by-arch in future patches.

MIPS is the exception here; it already uses the exact same rule as the
new common rule, so the duplicate is removed in this patch to avoid any
conflict. arch/mips changes courtesy of Ralf Baechle.

Update Documentation/kbuild to remove the explicit call to cmd_dtc from
the example, now that the rule exists in a centralized location.

Cc: Arnd Bergmann <>
Cc: Olof Johansson <>
Cc: Russell King <>
Acked-by: Catalin Marinas <>
Cc: Jonas Bonn <>
Cc: Aurelien Jacquiot <>
Cc: Mark Salter <>
Cc: Michal Simek <>
Cc: Chris Zankel <>
Cc: Max Filippov <>
Signed-off-by: Ralf Baechle <>
Signed-off-by: Stephen Warren <>
Signed-off-by: Rob Herring <>
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swarren authored and Rob Herring committed Nov 27, 2012
1 parent 4a92a38 commit 90b335fbbc316b58a0daee8ea792b5aa8903f2ae
@@ -1175,15 +1175,16 @@ When kbuild executes, the following steps are followed (roughly):
in an init section in the image. Platform code *must* copy the
blob to non-init memory prior to calling unflatten_device_tree().
- Example:
- #arch/x86/platform/ce4100/Makefile
- clean-files := *dtb.S
+ To use this command, simply add *.dtb into obj-y or targets, or make
+ some other target depend on %.dtb
- DTC_FLAGS := -p 1024
- obj-y += foo.dtb.o
+ A central rule exists to create $(obj)/%.dtb from $(src)/%.dts;
+ architecture Makefiles do no need to explicitly write out that rule.
- $(obj)/%.dtb: $(src)/%.dts
- $(call cmd,dtc)
+ Example:
+ targets += $(dtb-y)
+ clean-files += *.dtb
+ DTC_FLAGS ?= -p 1024
--- 6.8 Custom kbuild commands
@@ -24,9 +24,6 @@ DTB_FILES = $(patsubst %.dts, %.dtb, $(DTS_FILES))
obj-y += $(patsubst %.dts, %.dtb.o, $(DTS_FILES))
-$(obj)/%.dtb: $(src)/%.dts FORCE
- $(call if_changed_dep,dtc)
# Let's keep the .dtb files around in case we want to look at them.
.SECONDARY: $(addprefix $(obj)/, $(DTB_FILES))
@@ -1,4 +1 @@
obj-$(CONFIG_DT_EASY50712) := easy50712.dtb.o
-$(obj)/%.dtb: $(obj)/%.dts
- $(call if_changed,dtc)
@@ -1,4 +1 @@
obj-$(CONFIG_DT_XLP_EVP) := xlp_evp.dtb.o
-$(obj)/%.dtb: $(obj)/%.dts
- $(call if_changed,dtc)
@@ -266,6 +266,9 @@ $(obj)/%.dtb.S: $(obj)/%.dtb
quiet_cmd_dtc = DTC $@
cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile) $<
+$(obj)/%.dtb: $(src)/%.dts FORCE
+ $(call if_changed_dep,dtc)
# Bzip2
# ---------------------------------------------------------------------------

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