Kbuild.include 8.26 KB
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####
# kbuild: Generic definitions

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# Convenient constants
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comma   := ,
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squote  := '
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empty   :=
space   := $(empty) $(empty)

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###
# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
dot-target = $(dir $@).$(notdir $@)

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###
# The temporary file to save gcc -MD generated dependencies must not
# contain a comma
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depfile = $(subst $(comma),_,$(dot-target).d)
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###
# filename of target with directory and extension stripped
basetarget = $(basename $(notdir $@))

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###
# Escape single quote for use in echo statements
escsq = $(subst $(squote),'\$(squote)',$1)

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###
# filechk is used to check if the content of a generated file is updated.
# Sample usage:
# define filechk_sample
#	echo $KERNELRELEASE
# endef
# version.h : Makefile
#	$(call filechk,sample)
# The rule defined shall write to stdout the content of the new file.
# The existing file will be compared with the new one.
# - If no file exist it is created
# - If the content differ the new file is used
# - If they are equal no change, and no timestamp update
# - stdin is piped in from the first prerequisite ($<) so one has
#   to specify a valid file as first prerequisite (often the kbuild file)
define filechk
	$(Q)set -e;				\
	echo '  CHK     $@';			\
	mkdir -p $(dir $@);			\
	$(filechk_$(1)) < $< > $@.tmp;		\
	if [ -r $@ ] && cmp -s $@ $@.tmp; then	\
		rm -f $@.tmp;			\
	else					\
		echo '  UPD     $@';		\
		mv -f $@.tmp $@;		\
	fi
endef

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######
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# gcc support functions
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# See documentation in Documentation/kbuild/makefiles.txt

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# checker-shell
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# Usage: option = $(call checker-shell,$(CC)...-o $$OUT,option-ok,otherwise)
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# Exit code chooses option. $$OUT is safe location for needless output.
define checker-shell
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 $(strip
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  $(shell set -e; \
    DIR=$(KBUILD_EXTMOD); \
    cd $${DIR:-$(objtree)}; \
    OUT=$$PWD/.$$$$.null; \
    if $(1) >/dev/null 2>&1; \
      then echo "$(2)"; \
      else echo "$(3)"; \
    fi; \
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    rm -f $$OUT))
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endef
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# as-option
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# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
as-option = $(call checker-shell,\
   $(CC) $(CFLAGS) $(1) -c -xassembler /dev/null -o $$OUT,$(1),$(2))
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# as-instr
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# Usage: cflags-y += $(call as-instr,instr,option1,option2)
as-instr = $(call checker-shell,\
   printf "$(1)" | $(CC) $(AFLAGS) -c -xassembler -o $$OUT -,$(2),$(3))
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# cc-option
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# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
cc-option = $(call checker-shell,\
   $(CC) $(CFLAGS) $(if $(3),$(3),$(1)) -S -xc /dev/null -o $$OUT,$(1),$(2))
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# cc-option-yn
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# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
cc-option-yn = $(call cc-option,"y","n",$(1))
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# cc-option-align
# Prefix align with either -falign or -malign
cc-option-align = $(subst -functions=0,,\
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   $(call cc-option,-falign-functions=0,-malign-functions=0))
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# cc-version
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# Usage gcc-ver := $(call cc-version,$(CC))
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cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
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# cc-ifversion
# Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
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cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3))
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# ld-option
# Usage: ldflags += $(call ld-option, -Wl$(comma)--hash-style=both)
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ld-option = $(call checker-shell,\
   $(CC) $(1) -nostdlib -xc /dev/null -o $$OUT,$(1),$(2))
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######
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
# Usage:
# $(Q)$(MAKE) $(build)=dir
build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj

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# Prefix -I with $(srctree) if it is not an absolute path,
# add original to the end
addtree = $(if \
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	$(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1)
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# Find all -I options and call addtree
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flags = $(foreach o,$($(1)),\
	$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
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# echo command.
# 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)';)

# printing commands
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cmd = @$(echo-cmd) $(cmd_$(1))
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# Add $(obj)/ for paths that are not absolute
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objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
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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
# if_changed_dep  - as if_changed, but uses fixdep to reveal dependencies
#                   including used config symbols
# if_changed_rule - as if_changed but execute rule instead
# See Documentation/kbuild/makefiles.txt for more info

ifneq ($(KBUILD_NOCMDDEP),1)
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# Check if both arguments has same arguments. Result is empty string, if equal.
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# User may override this check using make KBUILD_NOCMDDEP=1
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arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
                    $(filter-out $(cmd_$@),   $(cmd_$(1))) )
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endif

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# >'< substitution is for echo to work,
# >$< substitution to preserve $ when reloading .cmd file
# note: when using inline perl scripts [perl -e '...$$t=1;...']
# in $(cmd_xxx) double $$ your perl vars
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make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))

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# Find any prerequisites that is newer than target or that does not exist.
# PHONY targets skipped in both cases.
any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)

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# Execute command if command has changed or prerequisite(s) are updated.
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#
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if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
	@set -e;                                                             \
	$(echo-cmd) $(cmd_$(1));                                             \
	echo '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 $(strip $(any-prereq) $(arg-check) ),                  \
	@set -e;                                                             \
	$(echo-cmd) $(cmd_$(1));                                             \
	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
	rm -f $(depfile);                                                    \
	mv -f $(dot-target).tmp $(dot-target).cmd)
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# Will check if $(cmd_foo) changed, or any of the prerequisites changed,
# and if so will execute $(rule_foo).
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# Usage: $(call if_changed_rule,foo)
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#
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if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ),                 \
	@set -e;                                                             \
	$(rule_$(1)))

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###
# why - tell why a a target got build
#       enabled by make V=2
#       Output (listed in the order they are checked):
#          (1) - due to target is PHONY
#          (2) - due to target missing
#          (3) - due to: file1.h file2.h
#          (4) - due to command line change
#          (5) - due to missing .cmd file
#          (6) - due to target not in $(targets)
# (1) PHONY targets are always build
# (2) No target, so we better build it
# (3) Prerequisite is newer than target
# (4) The command line stored in the file named dir/.target.cmd
#     differed from actual command line. This happens when compiler
#     options changes
# (5) No dir/.target.cmd file (used to store command line)
# (6) No dir/.target.cmd file and target not listed in $(targets)
#     This is a good hint that there is a bug in the kbuild file
ifeq ($(KBUILD_VERBOSE),2)
why =                                                                        \
    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
        $(if $(wildcard $@),                                                 \
            $(if $(strip $(any-prereq)),- due to: $(any-prereq),             \
                $(if $(arg-check),                                           \
                    $(if $(cmd_$@),- due to command line change,             \
                        $(if $(filter $@, $(targets)),                       \
                            - due to missing .cmd file,                      \
                            - due to $(notdir $@) not in $$(targets)         \
                         )                                                   \
                     )                                                       \
                 )                                                           \
             ),                                                              \
             - due to target missing                                         \
         )                                                                   \
     )

echo-why = $(call escsq, $(strip $(why)))
endif