linux-next/usr/include/Makefile
Masahiro Yamada 30a7729771 kbuild: use -MMD instead of -MD to exclude system headers from dependency
This omits system headers from the generated header dependency.

System headers are not updated unless you upgrade the compiler. Nor do
they contain CONFIG options, so fixdep does not need to parse them.

Having said that, the effect of this optimization will be quite small
because the kernel code generally does not include system headers
except <stdarg.h>. Host programs include a lot of system headers,
but there are not so many in the kernel tree.

At first, keeping system headers in .*.cmd files might be useful to
detect the compiler update, but there is no guarantee that <stdarg.h>
is included from every file. So, I implemented a more reliable way in
the previous commit.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-12 13:28:33 +09:00

108 lines
3.3 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0-only
# Unlike the kernel space, exported headers are written in standard C.
# - Forbid C++ style comments
# - Use '__inline__', '__asm__' instead of 'inline', 'asm'
#
# -std=c90 (equivalent to -ansi) catches the violation of those.
# We cannot go as far as adding -Wpedantic since it emits too many warnings.
UAPI_CFLAGS := -std=c90 -Wall -Werror=implicit-function-declaration
override c_flags = $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) -I$(objtree)/usr/include
# The following are excluded for now because they fail to build.
#
# Do not add a new header to the blacklist without legitimate reason.
# Please consider to fix the header first.
#
# Sorted alphabetically.
no-header-test += asm/shmbuf.h
no-header-test += asm/signal.h
no-header-test += asm/ucontext.h
no-header-test += drm/vmwgfx_drm.h
no-header-test += linux/am437x-vpfe.h
no-header-test += linux/android/binder.h
no-header-test += linux/android/binderfs.h
no-header-test += linux/coda.h
no-header-test += linux/elfcore.h
no-header-test += linux/errqueue.h
no-header-test += linux/fsmap.h
no-header-test += linux/hdlc/ioctl.h
no-header-test += linux/ivtv.h
no-header-test += linux/kexec.h
no-header-test += linux/matroxfb.h
no-header-test += linux/nfc.h
no-header-test += linux/omap3isp.h
no-header-test += linux/omapfb.h
no-header-test += linux/patchkey.h
no-header-test += linux/phonet.h
no-header-test += linux/reiserfs_xattr.h
no-header-test += linux/sctp.h
no-header-test += linux/signal.h
no-header-test += linux/sysctl.h
no-header-test += linux/usb/audio.h
no-header-test += linux/v4l2-mediabus.h
no-header-test += linux/v4l2-subdev.h
no-header-test += linux/videodev2.h
no-header-test += linux/vm_sockets.h
no-header-test += sound/asequencer.h
no-header-test += sound/asoc.h
no-header-test += sound/asound.h
no-header-test += sound/compress_offload.h
no-header-test += sound/emu10k1.h
no-header-test += sound/sfnt_info.h
no-header-test += xen/evtchn.h
no-header-test += xen/gntdev.h
no-header-test += xen/privcmd.h
# More headers are broken in some architectures
ifeq ($(SRCARCH),arc)
no-header-test += linux/bpf_perf_event.h
endif
ifeq ($(SRCARCH),ia64)
no-header-test += asm/setup.h
no-header-test += asm/sigcontext.h
no-header-test += asm/perfmon.h
no-header-test += asm/perfmon_default_smpl.h
no-header-test += linux/if_bonding.h
endif
ifeq ($(SRCARCH),mips)
no-header-test += asm/stat.h
endif
ifeq ($(SRCARCH),powerpc)
no-header-test += asm/stat.h
no-header-test += linux/bpf_perf_event.h
endif
ifeq ($(SRCARCH),riscv)
no-header-test += linux/bpf_perf_event.h
endif
ifeq ($(SRCARCH),sparc)
no-header-test += asm/stat.h
no-header-test += asm/uctx.h
no-header-test += asm/fbio.h
endif
# asm-generic/*.h is used by asm/*.h, and should not be included directly
no-header-test += asm-generic/%
extra-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h' 2>/dev/null))
# Include the header twice to detect missing include guard.
quiet_cmd_hdrtest = HDRTEST $<
cmd_hdrtest = \
$(CC) $(c_flags) -S -o /dev/null -x c /dev/null \
$(if $(filter-out $(no-header-test), $*.h), -include $< -include $<); \
$(PERL) $(srctree)/scripts/headers_check.pl $(obj) $(SRCARCH) $<; \
touch $@
$(obj)/%.hdrtest: $(obj)/%.h FORCE
$(call if_changed_dep,hdrtest)
clean-files += $(filter-out Makefile, $(notdir $(wildcard $(obj)/*)))