kbuild: make cc-version available in kbuild files (20a468b5) · Commits · 戴 / test

Documentation/kbuild/makefiles.txt

+97 −69

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@ This document describes the Linux kernel Makefiles.
		--- 3.8 Command line dependency
		--- 3.9 Dependency tracking
		--- 3.10 Special Rules
		--- 3.11 $(CC) support functions

		=== 4 Host Program support
		--- 4.1 Simple Host Program
		@@ -38,7 +39,6 @@ This document describes the Linux kernel Makefiles.
		--- 6.6 Commands useful for building a boot image
		--- 6.7 Custom kbuild commands
		--- 6.8 Preprocessing linker scripts
		--- 6.9 $(CC) support functions

		=== 7 Kbuild Variables
		=== 8 Makefile language
		@@ -385,6 +385,102 @@ more details, with real examples.
		to prerequisites are referenced with $(src) (because they are not
		generated files).

		--- 3.11 $(CC) support functions

		The kernel may be build with several different versions of
		$(CC), each supporting a unique set of features and options.
		kbuild provide basic support to check for valid options for $(CC).
		$(CC) is useally the gcc compiler, but other alternatives are
		available.

		as-option
		as-option is used to check if $(CC) when used to compile
		assembler (*.S) files supports the given option. An optional
		second option may be specified if first option are not supported.

		Example:
		#arch/sh/Makefile
		cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)

		In the above example cflags-y will be assinged the the option
		-Wa$(comma)-isa=$(isa-y) if it is supported by $(CC).
		The second argument is optional, and if supplied will be used
		if first argument is not supported.

		cc-option
		cc-option is used to check if $(CC) support a given option, and not
		supported to use an optional second option.

		Example:
		#arch/i386/Makefile
		cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)

		In the above example cflags-y will be assigned the option
		-march=pentium-mmx if supported by $(CC), otherwise -march-i586.
		The second argument to cc-option is optional, and if omitted
		cflags-y will be assigned no value if first option is not supported.

		cc-option-yn
		cc-option-yn is used to check if gcc supports a given option
		and return 'y' if supported, otherwise 'n'.

		Example:
		#arch/ppc/Makefile
		biarch := $(call cc-option-yn, -m32)
		aflags-$(biarch) += -a32
		cflags-$(biarch) += -m32

		In the above example $(biarch) is set to y if $(CC) supports the -m32
		option. When $(biarch) equals to y the expanded variables $(aflags-y)
		and $(cflags-y) will be assigned the values -a32 and -m32.

		cc-option-align
		gcc version >= 3.0 shifted type of options used to speify
		alignment of functions, loops etc. $(cc-option-align) whrn used
		as prefix to the align options will select the right prefix:
		gcc < 3.00
		cc-option-align = -malign
		gcc >= 3.00
		cc-option-align = -falign

		Example:
		CFLAGS += $(cc-option-align)-functions=4

		In the above example the option -falign-functions=4 is used for
		gcc >= 3.00. For gcc < 3.00 -malign-functions=4 is used.

		cc-version
		cc-version return a numerical version of the $(CC) compiler version.
		The format is <major><minor> where both are two digits. So for example
		gcc 3.41 would return 0341.
		cc-version is useful when a specific $(CC) version is faulty in one
		area, for example the -mregparm=3 were broken in some gcc version
		even though the option was accepted by gcc.

		Example:
		#arch/i386/Makefile
		cflags-y += $(shell \
		if [ $(call cc-version) -ge 0300 ] ; then \
		echo "-mregparm=3"; fi ;)

		In the above example -mregparm=3 is only used for gcc version greater
		than or equal to gcc 3.0.

		cc-ifversion
		cc-ifversion test the version of $(CC) and equals last argument if
		version expression is true.

		Example:
		#fs/reiserfs/Makefile
		EXTRA_CFLAGS := $(call cc-ifversion, -lt, 0402, -O1)

		In this example EXTRA_CFLAGS will be assigned the value -O1 if the
		$(CC) version is less than 4.2.
		cc-ifversion takes all the shell operators:
		-eq, -ne, -lt, -le, -gt, and -ge
		The third parameter may be a text as in this example, but it may also
		be an expanded variable or a macro.


		=== 4 Host Program support

		@@ -973,74 +1069,6 @@ When kbuild executes the following steps are followed (roughly):
		architecture specific files.


		--- 6.9 $(CC) support functions

		The kernel may be build with several different versions of
		$(CC), each supporting a unique set of features and options.
		kbuild provide basic support to check for valid options for $(CC).
		$(CC) is useally the gcc compiler, but other alternatives are
		available.

		cc-option
		cc-option is used to check if $(CC) support a given option, and not
		supported to use an optional second option.

		Example:
		#arch/i386/Makefile
		cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)

		In the above example cflags-y will be assigned the option
		-march=pentium-mmx if supported by $(CC), otherwise -march-i586.
		The second argument to cc-option is optional, and if omitted
		cflags-y will be assigned no value if first option is not supported.

		cc-option-yn
		cc-option-yn is used to check if gcc supports a given option
		and return 'y' if supported, otherwise 'n'.

		Example:
		#arch/ppc/Makefile
		biarch := $(call cc-option-yn, -m32)
		aflags-$(biarch) += -a32
		cflags-$(biarch) += -m32

		In the above example $(biarch) is set to y if $(CC) supports the -m32
		option. When $(biarch) equals to y the expanded variables $(aflags-y)
		and $(cflags-y) will be assigned the values -a32 and -m32.

		cc-option-align
		gcc version >= 3.0 shifted type of options used to speify
		alignment of functions, loops etc. $(cc-option-align) whrn used
		as prefix to the align options will select the right prefix:
		gcc < 3.00
		cc-option-align = -malign
		gcc >= 3.00
		cc-option-align = -falign

		Example:
		CFLAGS += $(cc-option-align)-functions=4

		In the above example the option -falign-functions=4 is used for
		gcc >= 3.00. For gcc < 3.00 -malign-functions=4 is used.

		cc-version
		cc-version return a numerical version of the $(CC) compiler version.
		The format is <major><minor> where both are two digits. So for example
		gcc 3.41 would return 0341.
		cc-version is useful when a specific $(CC) version is faulty in one
		area, for example the -mregparm=3 were broken in some gcc version
		even though the option was accepted by gcc.

		Example:
		#arch/i386/Makefile
		cflags-y += $(shell \
		if [ $(call cc-version) -ge 0300 ] ; then \
		echo "-mregparm=3"; fi ;)

		In the above example -mregparm=3 is only used for gcc version greater
		than or equal to gcc 3.0.


		=== 7 Kbuild Variables

		The top Makefile exports the following variables:

Makefile

+0 −32

Original line number	Diff line number	Diff line
		@@ -258,38 +258,6 @@ endif

		export quiet Q KBUILD_VERBOSE

		######
		# cc support functions to be used (only) in arch/$(ARCH)/Makefile
		# See documentation in Documentation/kbuild/makefiles.txt

		# as-option
		# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,)

		as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
		-xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
		else echo "$(2)"; fi ;)

		# cc-option
		# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)

		cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
		> /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)

		# cc-option-yn
		# Usage: flag := $(call cc-option-yn, -march=winchip-c6)
		cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
		> /dev/null 2>&1; then echo "y"; else echo "n"; fi;)

		# cc-option-align
		# Prefix align with either -falign or -malign
		cc-option-align = $(subst -functions=0,,\
		$(call cc-option,-falign-functions=0,-malign-functions=0))

		# cc-version
		# Usage gcc-ver := $(call cc-version $(CC))
		cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \
		$(if $(1), $(1), $(CC)))


		# Look for make include files relative to root of kernel src
		MAKEFLAGS += --include-dir=$(srctree)

scripts/Kbuild.include

+37 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,43 @@ define filechk
		fi
		endef

		######
		# cc support functions to be used (only) in arch/$(ARCH)/Makefile
		# See documentation in Documentation/kbuild/makefiles.txt

		# as-option
		# Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,)

		as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
		-xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
		else echo "$(2)"; fi ;)

		# cc-option
		# Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)

		cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
		> /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)

		# cc-option-yn
		# Usage: flag := $(call cc-option-yn, -march=winchip-c6)
		cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
		> /dev/null 2>&1; then echo "y"; else echo "n"; fi;)

		# cc-option-align
		# Prefix align with either -falign or -malign
		cc-option-align = $(subst -functions=0,,\
		$(call cc-option,-falign-functions=0,-malign-functions=0))

		# cc-version
		# Usage gcc-ver := $(call cc-version, $(CC))
		cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \
		$(if $(1), $(1), $(CC)))

		# cc-ifversion
		# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
		cc-ifversion = $(shell if [ $(call cc-version, $(CC)) $(1) $(2) ]; then \
		echo $(3); fi;)

		###
		# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
		# Usage:

scripts/Makefile.build

+2 −1

Original line number	Diff line number	Diff line
		@@ -10,11 +10,12 @@ __build:
		# Read .config if it exist, otherwise ignore
		-include .config

		include scripts/Kbuild.include

		# The filename Kbuild has precedence over Makefile
		kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
		include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)

		include scripts/Kbuild.include
		include scripts/Makefile.lib

		ifdef host-progs

Admin message