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https://github.com/torvalds/linux
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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 $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
65 lines
1.9 KiB
Makefile
65 lines
1.9 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for the linux kernel.
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#
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ccflags-y := -fno-function-sections -fno-data-sections
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obj-y := main.o version.o mounts.o
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ifneq ($(CONFIG_BLK_DEV_INITRD),y)
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obj-y += noinitramfs.o
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else
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obj-$(CONFIG_BLK_DEV_INITRD) += initramfs.o
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endif
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obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
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obj-y += init_task.o
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mounts-y := do_mounts.o
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mounts-$(CONFIG_BLK_DEV_RAM) += do_mounts_rd.o
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mounts-$(CONFIG_BLK_DEV_INITRD) += do_mounts_initrd.o
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#
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# UTS_VERSION
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#
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smp-flag-$(CONFIG_SMP) := SMP
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preempt-flag-$(CONFIG_PREEMPT_BUILD) := PREEMPT
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preempt-flag-$(CONFIG_PREEMPT_DYNAMIC) := PREEMPT_DYNAMIC
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preempt-flag-$(CONFIG_PREEMPT_RT) := PREEMPT_RT
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build-version = $(or $(KBUILD_BUILD_VERSION), $(build-version-auto))
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build-timestamp = $(or $(KBUILD_BUILD_TIMESTAMP), $(build-timestamp-auto))
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# Maximum length of UTS_VERSION is 64 chars
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filechk_uts_version = \
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utsver=$$(echo '$(pound)'"$(build-version)" $(smp-flag-y) $(preempt-flag-y) "$(build-timestamp)" | cut -b -64); \
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echo '$(pound)'define UTS_VERSION \""$${utsver}"\"
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#
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# Build version.c with temporary UTS_VERSION
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#
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$(obj)/utsversion-tmp.h: FORCE
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$(call filechk,uts_version)
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clean-files += utsversion-tmp.h
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$(obj)/version.o: $(obj)/utsversion-tmp.h
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CFLAGS_version.o := -include $(obj)/utsversion-tmp.h
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#
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# Build version-timestamp.c with final UTS_VERSION
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#
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include/generated/utsversion.h: build-version-auto = $(shell $(src)/build-version)
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include/generated/utsversion.h: build-timestamp-auto = $(shell LC_ALL=C date)
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include/generated/utsversion.h: FORCE
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$(call filechk,uts_version)
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$(obj)/version-timestamp.o: include/generated/utsversion.h
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CFLAGS_version-timestamp.o := -include include/generated/utsversion.h
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KASAN_SANITIZE_version-timestamp.o := n
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KCSAN_SANITIZE_version-timestamp.o := n
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GCOV_PROFILE_version-timestamp.o := n
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