b1992c3772
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
59 lines
1.8 KiB
Makefile
59 lines
1.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# include/asm-generic contains a lot of files that are used
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# verbatim by several architectures.
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#
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# This Makefile reads the file arch/$(SRCARCH)/include/(uapi/)/asm/Kbuild
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# and for each file listed in this file with generic-y creates
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# a small wrapper file in arch/$(SRCARCH)/include/generated/(uapi/)/asm.
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PHONY := all
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all:
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src := $(srctree)/$(subst /generated,,$(obj))
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include $(srctree)/scripts/Kbuild.include
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-include $(kbuild-file)
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# $(generic)/Kbuild lists mandatory-y. Exclude um since it is a special case.
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ifneq ($(SRCARCH),um)
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include $(srctree)/$(generic)/Kbuild
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endif
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redundant := $(filter $(mandatory-y) $(generated-y), $(generic-y))
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redundant += $(foreach f, $(generic-y), $(if $(wildcard $(src)/$(f)),$(f)))
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redundant := $(sort $(redundant))
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$(if $(redundant),\
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$(warning redundant generic-y found in $(src)/Kbuild: $(redundant)))
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# If arch does not implement mandatory headers, fallback to asm-generic ones.
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mandatory-y := $(filter-out $(generated-y), $(mandatory-y))
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generic-y += $(foreach f, $(mandatory-y), $(if $(wildcard $(src)/$(f)),,$(f)))
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generic-y := $(addprefix $(obj)/, $(generic-y))
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generated-y := $(addprefix $(obj)/, $(generated-y))
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# Remove stale wrappers when the corresponding files are removed from generic-y
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old-headers := $(wildcard $(obj)/*.h)
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unwanted := $(filter-out $(generic-y) $(generated-y),$(old-headers))
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quiet_cmd_wrap = WRAP $@
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cmd_wrap = echo "\#include <asm-generic/$*.h>" > $@
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quiet_cmd_remove = REMOVE $(unwanted)
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cmd_remove = rm -f $(unwanted)
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all: $(generic-y)
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$(if $(unwanted),$(call cmd,remove))
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@:
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$(obj)/%.h:
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$(call cmd,wrap)
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# Create output directory. Skip it if at least one old header exists
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# since we know the output directory already exists.
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ifeq ($(old-headers),)
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$(shell mkdir -p $(obj))
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endif
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.PHONY: $(PHONY)
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