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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>
90 lines
3.0 KiB
Makefile
90 lines
3.0 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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# Unlike the kernel space, exported headers are written in standard C.
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# - Forbid C++ style comments
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# - Use '__inline__', '__asm__' instead of 'inline', 'asm'
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#
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# -std=c90 (equivalent to -ansi) catches the violation of those.
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# We cannot go as far as adding -Wpedantic since it emits too many warnings.
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UAPI_CFLAGS := -std=c90 -Wall -Werror=implicit-function-declaration
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# In theory, we do not care -m32 or -m64 for header compile tests.
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# It is here just because CONFIG_CC_CAN_LINK is tested with -m32 or -m64.
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UAPI_CFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
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# USERCFLAGS might contain sysroot location for CC.
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UAPI_CFLAGS += $(USERCFLAGS)
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override c_flags = $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) -I $(obj) -I $(srctree)/usr/dummy-include
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# The following are excluded for now because they fail to build.
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#
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# Do not add a new header to the blacklist without legitimate reason.
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# Please consider to fix the header first.
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#
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# Sorted alphabetically.
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no-header-test += asm/ucontext.h
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no-header-test += drm/vmwgfx_drm.h
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no-header-test += linux/am437x-vpfe.h
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no-header-test += linux/coda.h
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no-header-test += linux/cyclades.h
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no-header-test += linux/errqueue.h
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no-header-test += linux/hdlc/ioctl.h
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no-header-test += linux/ivtv.h
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no-header-test += linux/matroxfb.h
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no-header-test += linux/omap3isp.h
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no-header-test += linux/omapfb.h
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no-header-test += linux/patchkey.h
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no-header-test += linux/phonet.h
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no-header-test += linux/sctp.h
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no-header-test += linux/sysctl.h
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no-header-test += linux/usb/audio.h
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no-header-test += linux/v4l2-mediabus.h
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no-header-test += linux/v4l2-subdev.h
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no-header-test += linux/videodev2.h
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no-header-test += linux/vm_sockets.h
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no-header-test += sound/asequencer.h
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no-header-test += sound/asoc.h
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no-header-test += sound/asound.h
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no-header-test += sound/compress_offload.h
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no-header-test += sound/emu10k1.h
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no-header-test += sound/sfnt_info.h
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no-header-test += xen/evtchn.h
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no-header-test += xen/gntdev.h
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no-header-test += xen/privcmd.h
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# More headers are broken in some architectures
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ifeq ($(SRCARCH),arc)
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no-header-test += linux/bpf_perf_event.h
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endif
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ifeq ($(SRCARCH),powerpc)
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no-header-test += linux/bpf_perf_event.h
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endif
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ifeq ($(SRCARCH),sparc)
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no-header-test += asm/uctx.h
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no-header-test += asm/fbio.h
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endif
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# asm-generic/*.h is used by asm/*.h, and should not be included directly
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no-header-test += asm-generic/%
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always-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h' 2>/dev/null))
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# Include the header twice to detect missing include guard.
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quiet_cmd_hdrtest = HDRTEST $<
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cmd_hdrtest = \
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$(CC) $(c_flags) -fsyntax-only -x c /dev/null \
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$(if $(filter-out $(no-header-test), $*.h), -include $< -include $<); \
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$(PERL) $(src)/headers_check.pl $(obj) $(SRCARCH) $<; \
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touch $@
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$(obj)/%.hdrtest: $(obj)/%.h FORCE
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$(call if_changed_dep,hdrtest)
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# Since GNU Make 4.3, $(patsubst $(obj)/%/,%,$(wildcard $(obj)/*/)) works.
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# To support older Make versions, use a somewhat tedious way.
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clean-files += $(filter-out Makefile headers_check.pl, $(notdir $(wildcard $(obj)/*)))
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