mirror of
https://github.com/torvalds/linux
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8b41fc4454
Commit bc081dd6e9 ("kbuild: generate modules.builtin") added
infrastructure to generate modules.builtin, the list of all
builtin modules.
Basically, it works like this:
- Kconfig generates include/config/tristate.conf, the list of
tristate CONFIG options with a value in a capital letter.
- scripts/Makefile.modbuiltin makes Kbuild descend into
directories to collect the information of builtin modules.
I am not a big fan of it because Kbuild ends up with traversing
the source tree twice.
I am not sure how perfectly it should work, but this approach cannot
avoid false positives; even if the relevant CONFIG option is tristate,
some Makefiles forces obj-m to obj-y.
Some examples are:
arch/powerpc/platforms/powermac/Makefile:
obj-$(CONFIG_NVRAM:m=y) += nvram.o
net/ipv6/Makefile:
obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o
net/netlabel/Makefile:
obj-$(subst m,y,$(CONFIG_IPV6)) += netlabel_calipso.o
Nobody has complained about (or noticed) it, so it is probably fine to
have false positives in modules.builtin.
This commit simplifies the implementation. Let's exploit the fact
that every module has MODULE_LICENSE(). (modpost shows a warning if
MODULE_LICENSE is missing. If so, 0-day bot would already have blocked
such a module.)
I added MODULE_FILE to <linux/module.h>. When the code is being compiled
as builtin, it will be filled with the file path of the module, and
collected into modules.builtin.info. Then, scripts/link-vmlinux.sh
extracts the list of builtin modules out of it.
This new approach fixes the false-positives above, but adds another
type of false-positives; non-modular code may have MODULE_LICENSE()
by mistake. This is not a big deal, it is just the code is always
orphan. We can clean it up if we like. You can see cleanup examples by:
$ git log --grep='make.* explicitly non-modular'
To sum up, this commits deletes lots of code, but still produces almost
equivalent results. Please note it does not increase the vmlinux size at
all. As you can see in include/asm-generic/vmlinux.lds.h, the .modinfo
section is discarded in the link stage.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
330 lines
12 KiB
Plaintext
330 lines
12 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
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####
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# kbuild: Generic definitions
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# Convenient variables
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comma := ,
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quote := "
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squote := '
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empty :=
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space := $(empty) $(empty)
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space_escape := _-_SPACE_-_
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pound := \#
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###
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# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
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dot-target = $(dir $@).$(notdir $@)
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###
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# The temporary file to save gcc -MD generated dependencies must not
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# contain a comma
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depfile = $(subst $(comma),_,$(dot-target).d)
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###
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# filename of target with directory and extension stripped
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basetarget = $(basename $(notdir $@))
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###
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# real prerequisites without phony targets
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real-prereqs = $(filter-out $(PHONY), $^)
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###
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# Escape single quote for use in echo statements
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escsq = $(subst $(squote),'\$(squote)',$1)
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###
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# Quote a string to pass it to C files. foo => '"foo"'
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stringify = $(squote)$(quote)$1$(quote)$(squote)
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###
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# Easy method for doing a status message
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kecho := :
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quiet_kecho := echo
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silent_kecho := :
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kecho := $($(quiet)kecho)
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###
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# filechk is used to check if the content of a generated file is updated.
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# Sample usage:
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#
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# filechk_sample = echo $(KERNELRELEASE)
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# version.h: FORCE
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# $(call filechk,sample)
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#
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# The rule defined shall write to stdout the content of the new file.
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# The existing file will be compared with the new one.
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# - If no file exist it is created
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# - If the content differ the new file is used
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# - If they are equal no change, and no timestamp update
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# - stdin is piped in from the first prerequisite ($<) so one has
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# to specify a valid file as first prerequisite (often the kbuild file)
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define filechk
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$(Q)set -e; \
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mkdir -p $(dir $@); \
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{ $(filechk_$(1)); } > $@.tmp; \
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if [ -r $@ ] && cmp -s $@ $@.tmp; then \
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rm -f $@.tmp; \
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else \
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$(kecho) ' UPD $@'; \
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mv -f $@.tmp $@; \
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fi
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endef
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######
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# gcc support functions
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# See documentation in Documentation/kbuild/makefiles.rst
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# cc-cross-prefix
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# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
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# Return first <prefix> where a <prefix>gcc is found in PATH.
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# If no gcc found in PATH with listed prefixes return nothing
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#
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# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it
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# would try to directly execute the shell builtin 'command'. This workaround
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# should be kept for a long time since this issue was fixed only after the
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# GNU Make 4.2.1 release.
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cc-cross-prefix = $(firstword $(foreach c, $(1), \
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$(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c))))
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# output directory for tests below
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TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
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# try-run
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# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
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# Exit code chooses option. "$$TMP" serves as a temporary file and is
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# automatically cleaned up.
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try-run = $(shell set -e; \
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TMP="$(TMPOUT).$$$$.tmp"; \
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TMPO="$(TMPOUT).$$$$.o"; \
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if ($(1)) >/dev/null 2>&1; \
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then echo "$(2)"; \
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else echo "$(3)"; \
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fi; \
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rm -f "$$TMP" "$$TMPO")
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# as-option
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# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
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as-option = $(call try-run,\
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$(CC) $(KBUILD_CFLAGS) $(1) -c -x assembler /dev/null -o "$$TMP",$(1),$(2))
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# as-instr
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# Usage: cflags-y += $(call as-instr,instr,option1,option2)
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as-instr = $(call try-run,\
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printf "%b\n" "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
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# __cc-option
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# Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586)
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__cc-option = $(call try-run,\
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$(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4))
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# Do not attempt to build with gcc plugins during cc-option tests.
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# (And this uses delayed resolution so the flags will be up to date.)
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CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
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# cc-option
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# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
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cc-option = $(call __cc-option, $(CC),\
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$(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
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# cc-option-yn
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# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
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cc-option-yn = $(call try-run,\
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$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
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# cc-disable-warning
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# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
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cc-disable-warning = $(call try-run,\
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$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
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# cc-ifversion
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# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
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cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
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# ld-option
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# Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
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ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
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# ld-version
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# Note this is mainly for HJ Lu's 3 number binutil versions
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ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)
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# ld-ifversion
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# Usage: $(call ld-ifversion, -ge, 22252, y)
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ld-ifversion = $(shell [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4))
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######
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
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# Usage:
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# $(Q)$(MAKE) $(build)=dir
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build := -f $(srctree)/scripts/Makefile.build obj
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj=
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# Usage:
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# $(Q)$(MAKE) $(dtbinst)=dir
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dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=
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# Usage:
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# $(Q)$(MAKE) $(clean)=dir
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clean := -f $(srctree)/scripts/Makefile.clean obj
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# echo command.
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# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
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echo-cmd = $(if $($(quiet)cmd_$(1)),\
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echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
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# printing commands
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cmd = @set -e; $(echo-cmd) $(cmd_$(1))
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###
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# if_changed - execute command if any prerequisite is newer than
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# target, or command line has changed
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# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
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# including used config symbols
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# if_changed_rule - as if_changed but execute rule instead
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# See Documentation/kbuild/makefiles.rst for more info
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ifneq ($(KBUILD_NOCMDDEP),1)
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# Check if both commands are the same including their order. Result is empty
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# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
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cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
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$(subst $(space),$(space_escape),$(strip $(cmd_$1))))
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else
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cmd-check = $(if $(strip $(cmd_$@)),,1)
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endif
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# Replace >$< with >$$< to preserve $ when reloading the .cmd file
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# (needed for make)
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# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
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# (needed for make)
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# Replace >'< with >'\''< to be able to enclose the whole string in '...'
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# (needed for the shell)
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make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
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# Find any prerequisites that are newer than target or that do not exist.
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# (This is not true for now; $? should contain any non-existent prerequisites,
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# but it does not work as expected when .SECONDARY is present. This seems a bug
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# of GNU Make.)
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# PHONY targets skipped in both cases.
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newer-prereqs = $(filter-out $(PHONY),$?)
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# Execute command if command has changed or prerequisite(s) are updated.
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if_changed = $(if $(newer-prereqs)$(cmd-check), \
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$(cmd); \
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printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
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# Execute the command and also postprocess generated .d dependencies file.
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if_changed_dep = $(if $(newer-prereqs)$(cmd-check),$(cmd_and_fixdep),@:)
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cmd_and_fixdep = \
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$(cmd); \
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scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
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rm -f $(depfile)
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# Usage: $(call if_changed_rule,foo)
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# Will check if $(cmd_foo) or any of the prerequisites changed,
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# and if so will execute $(rule_foo).
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if_changed_rule = $(if $(newer-prereqs)$(cmd-check),$(rule_$(1)),@:)
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###
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# why - tell why a target got built
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# enabled by make V=2
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# Output (listed in the order they are checked):
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# (1) - due to target is PHONY
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# (2) - due to target missing
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# (3) - due to: file1.h file2.h
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# (4) - due to command line change
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# (5) - due to missing .cmd file
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# (6) - due to target not in $(targets)
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# (1) PHONY targets are always build
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# (2) No target, so we better build it
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# (3) Prerequisite is newer than target
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# (4) The command line stored in the file named dir/.target.cmd
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# differed from actual command line. This happens when compiler
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# options changes
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# (5) No dir/.target.cmd file (used to store command line)
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# (6) No dir/.target.cmd file and target not listed in $(targets)
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# This is a good hint that there is a bug in the kbuild file
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ifeq ($(KBUILD_VERBOSE),2)
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why = \
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$(if $(filter $@, $(PHONY)),- due to target is PHONY, \
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$(if $(wildcard $@), \
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$(if $(newer-prereqs),- due to: $(newer-prereqs), \
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$(if $(cmd-check), \
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$(if $(cmd_$@),- due to command line change, \
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$(if $(filter $@, $(targets)), \
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- due to missing .cmd file, \
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- due to $(notdir $@) not in $$(targets) \
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) \
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) \
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) \
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), \
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- due to target missing \
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) \
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)
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echo-why = $(call escsq, $(strip $(why)))
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endif
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###############################################################################
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#
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# When a Kconfig string contains a filename, it is suitable for
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# passing to shell commands. It is surrounded by double-quotes, and
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# any double-quotes or backslashes within it are escaped by
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# backslashes.
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#
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# This is no use for dependencies or $(wildcard). We need to strip the
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# surrounding quotes and the escaping from quotes and backslashes, and
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# we *do* need to escape any spaces in the string. So, for example:
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#
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# Usage: $(eval $(call config_filename,FOO))
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#
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# Defines FOO_FILENAME based on the contents of the CONFIG_FOO option,
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# transformed as described above to be suitable for use within the
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# makefile.
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#
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# Also, if the filename is a relative filename and exists in the source
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# tree but not the build tree, define FOO_SRCPREFIX as $(srctree)/ to
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# be prefixed to *both* command invocation and dependencies.
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#
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# Note: We also print the filenames in the quiet_cmd_foo text, and
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# perhaps ought to have a version specially escaped for that purpose.
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# But it's only cosmetic, and $(patsubst "%",%,$(CONFIG_FOO)) is good
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# enough. It'll strip the quotes in the common case where there's no
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# space and it's a simple filename, and it'll retain the quotes when
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# there's a space. There are some esoteric cases in which it'll print
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# the wrong thing, but we don't really care. The actual dependencies
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# and commands *do* get it right, with various combinations of single
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# and double quotes, backslashes and spaces in the filenames.
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#
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###############################################################################
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#
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define config_filename
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ifneq ($$(CONFIG_$(1)),"")
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$(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
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ifneq ($$(patsubst /%,%,$$(firstword $$($(1)_FILENAME))),$$(firstword $$($(1)_FILENAME)))
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else
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ifeq ($$(wildcard $$($(1)_FILENAME)),)
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ifneq ($$(wildcard $$(srctree)/$$($(1)_FILENAME)),)
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$(1)_SRCPREFIX := $(srctree)/
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endif
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endif
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endif
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endif
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endef
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#
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###############################################################################
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# delete partially updated (i.e. corrupted) files on error
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.DELETE_ON_ERROR:
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# do not delete intermediate files automatically
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.SECONDARY:
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