Commit 58f051fc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'kbuild-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild 

Pull Kbuild updates from Masahiro Yamada:

 - Clean up Makefiles and scripts

 - Improve clang support

 - Remove unneeded genhdr-y syntax

 - Remove unneeded cc-option-align macro

 - Introduce __cc-option macro and use it to fix x86 boot code compiler
   flags

* tag 'kbuild-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: improve comments on KBUILD_SRC
  x86/build: Specify stack alignment for clang
  x86/build: Use __cc-option for boot code compiler options
  kbuild: Add __cc-option macro
  kbuild: remove cc-option-align
  kbuild: replace genhdr-y with generated-y
  kbuild: clang: Disable 'address-of-packed-member' warning
  kbuild: remove duplicated arch/*/include/generated/uapi include path
  kbuild: speed up checksyscalls.sh
  kbuild: simplify silent build (-s) detection
parents ef3ad089 c4e6fff1

Documentation/kbuild/makefiles.txt

+6 −35
Original line number Diff line number Diff line
@@ -45,10 +45,9 @@ This document describes the Linux kernel Makefiles. 


	=== 7 Kbuild syntax for exported headers

		--- 7.1 no-export-headers

		--- 7.2 genhdr-y

		--- 7.3 generic-y

		--- 7.4 generated-y

		--- 7.5 mandatory-y

		--- 7.2 generic-y

		--- 7.3 generated-y

		--- 7.4 mandatory-y



	=== 8 Kbuild Variables

	=== 9 Makefile language
@@ -487,22 +486,6 @@ more details, with real examples. 
	respectively.

	Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options



    cc-option-align

	gcc versions >= 3.0 changed the type of options used to specify

	alignment of functions, loops etc. $(cc-option-align), when 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:

		KBUILD_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.

	Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options



    cc-disable-warning

	cc-disable-warning checks if gcc supports a given warning and returns

	the commandline switch to disable it. This special function is needed,
@@ -1277,18 +1260,7 @@ See subsequent chapter for the syntax of the Kbuild file. 
	avoid exporting specific headers (e.g. kvm.h) on architectures that do

	not support it. It should be avoided as much as possible.



	--- 7.2 genhdr-y



	genhdr-y specifies asm files to be generated.



		Example:

			#arch/x86/include/uapi/asm/Kbuild

			genhdr-y += unistd_32.h

			genhdr-y += unistd_64.h

			genhdr-y += unistd_x32.h





	--- 7.3 generic-y

	--- 7.2 generic-y



	If an architecture uses a verbatim copy of a header from

	include/asm-generic then this is listed in the file
@@ -1315,11 +1287,10 @@ See subsequent chapter for the syntax of the Kbuild file. 
		Example: termios.h

			#include <asm-generic/termios.h>



	--- 7.4 generated-y

	--- 7.3 generated-y



	If an architecture generates other header files alongside generic-y

	wrappers, and not included in genhdr-y, then generated-y specifies

	them.

	wrappers, generated-y specifies them.



	This prevents them being treated as stale asm-generic wrappers and

	removed.

Makefile

+8 −16
Original line number Diff line number Diff line
@@ -84,17 +84,10 @@ endif 
# If the user is running make -s (silent mode), suppress echoing of

# commands



ifneq ($(filter 4.%,$(MAKE_VERSION)),)	# make-4

ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)

ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)

  quiet=silent_

  tools_silent=s

endif

else					# make-3.8x

ifneq ($(filter s% -s%,$(MAKEFLAGS)),)

  quiet=silent_

  tools_silent=-s

endif

endif



export quiet Q KBUILD_VERBOSE
@@ -113,8 +106,8 @@ export quiet Q KBUILD_VERBOSE 
# The O= assignment takes precedence over the KBUILD_OUTPUT environment

# variable.



# KBUILD_SRC is set on invocation of make in OBJ directory

# KBUILD_SRC is not intended to be used by the regular user (for now)

# KBUILD_SRC is not intended to be used by the regular user (for now),

# it is set on invocation of make with KBUILD_OUTPUT or O= specified.

ifeq ($(KBUILD_SRC),)



# OK, Make called in directory where kernel src resides
@@ -135,7 +128,6 @@ ifneq ($(words $(subst :, ,$(CURDIR))), 1) 
endif



ifneq ($(KBUILD_OUTPUT),)

# Invoke a second make in the output directory, passing relevant variables

# check that the output directory actually exists

saved-output := $(KBUILD_OUTPUT)

KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
@@ -148,6 +140,7 @@ PHONY += $(MAKECMDGOALS) sub-make 
$(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make

	@:



# Invoke a second make in the output directory, passing relevant variables

sub-make:

	$(Q)$(MAKE) -C $(KBUILD_OUTPUT) KBUILD_SRC=$(CURDIR) \

	-f $(CURDIR)/Makefile $(filter-out _all sub-make,$(MAKECMDGOALS))
@@ -303,7 +296,7 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \ 


HOSTCC       = gcc

HOSTCXX      = g++

HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89

HOSTCFLAGS   := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89

HOSTCXXFLAGS = -O2



ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
@@ -388,12 +381,10 @@ USERINCLUDE := \ 
# Needed to be compatible with the O= option

LINUXINCLUDE    := \

		-I$(srctree)/arch/$(hdr-arch)/include \

		-I$(objtree)/arch/$(hdr-arch)/include/generated/uapi \

		-I$(objtree)/arch/$(hdr-arch)/include/generated \

		$(if $(KBUILD_SRC), -I$(srctree)/include) \

		-I$(objtree)/include



LINUXINCLUDE	+= $(filter-out $(LINUXINCLUDE),$(USERINCLUDE))

		-I$(objtree)/include \

		$(USERINCLUDE)



KBUILD_CPPFLAGS := -D__KERNEL__
@@ -707,6 +698,7 @@ KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) 
KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)

KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)

KBUILD_CFLAGS += $(call cc-disable-warning, gnu)

KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)

# Quiet clang warning: comparison of unsigned expression < 0 is always false

KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)

# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the

arch/arm/include/uapi/asm/Kbuild

+3 −3
Original line number Diff line number Diff line 
# UAPI Header export list

include include/uapi/asm-generic/Kbuild.asm



genhdr-y += unistd-common.h

genhdr-y += unistd-oabi.h

genhdr-y += unistd-eabi.h

generated-y += unistd-common.h

generated-y += unistd-oabi.h

generated-y += unistd-eabi.h



generic-y += siginfo.h

arch/x86/Makefile

+25 −8
Original line number Diff line number Diff line
@@ -11,6 +11,14 @@ else 
        KBUILD_DEFCONFIG := $(ARCH)_defconfig

endif



# For gcc stack alignment is specified with -mpreferred-stack-boundary,

# clang has the option -mstack-alignment for that purpose.

ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)

        cc_stack_align_opt := -mpreferred-stack-boundary

else ifneq ($(call cc-option, -mstack-alignment=4),)

        cc_stack_align_opt := -mstack-alignment

endif



# How to compile the 16-bit code.  Note we always compile for -march=i386;

# that way we can complain to the user if the CPU is insufficient.

#
@@ -24,10 +32,11 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \ 
		   -DDISABLE_BRANCH_PROFILING \

		   -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \

		   -fno-strict-aliasing -fomit-frame-pointer -fno-pic \

		   -mno-mmx -mno-sse \

		   $(call cc-option, -ffreestanding) \

		   $(call cc-option, -fno-stack-protector) \

		   $(call cc-option, -mpreferred-stack-boundary=2)

		   -mno-mmx -mno-sse



REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding)

REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector)

REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align_opt)=2)

export REALMODE_CFLAGS



# BITS is used as extension for files which are available in a 32 bit
@@ -64,8 +73,10 @@ ifeq ($(CONFIG_X86_32),y) 
        # with nonstandard options

        KBUILD_CFLAGS += -fno-pic



        # prevent gcc from keeping the stack 16 byte aligned

        KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=2)

        # Align the stack to the register width instead of using the default

        # alignment of 16 bytes. This reduces stack usage and the number of

        # alignment instructions.

        KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align_opt)=2)



        # Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use

        # a lot more stack due to the lack of sharing of stacklots:
@@ -97,8 +108,14 @@ else 
        KBUILD_CFLAGS += $(call cc-option,-mno-80387)

        KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)



	# Use -mpreferred-stack-boundary=3 if supported.

	KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)

        # By default gcc and clang use a stack alignment of 16 bytes for x86.

        # However the standard kernel entry on x86-64 leaves the stack on an

        # 8-byte boundary. If the compiler isn't informed about the actual

        # alignment it will generate extra alignment instructions for the

        # default alignment which keep the stack *mis*aligned.

        # Furthermore an alignment to the register width reduces stack usage

        # and the number of alignment instructions.

        KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align_opt)=3)



	# Use -mskip-rax-setup if supported.

	KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)

arch/x86/Makefile_32.cpu

+3 −4
Original line number Diff line number Diff line
@@ -9,7 +9,6 @@ else 
tune		= $(call cc-option,-mcpu=$(1),$(2))

endif



align := $(cc-option-align)

cflags-$(CONFIG_M486)		+= -march=i486

cflags-$(CONFIG_M586)		+= -march=i586

cflags-$(CONFIG_M586TSC)	+= -march=i586
@@ -24,11 +23,11 @@ cflags-$(CONFIG_MK6) += -march=k6 
# They make zero difference whatsosever to performance at this time.

cflags-$(CONFIG_MK7)		+= -march=athlon

cflags-$(CONFIG_MK8)		+= $(call cc-option,-march=k8,-march=athlon)

cflags-$(CONFIG_MCRUSOE)	+= -march=i686 $(align)-functions=0 $(align)-jumps=0 $(align)-loops=0

cflags-$(CONFIG_MEFFICEON)	+= -march=i686 $(call tune,pentium3) $(align)-functions=0 $(align)-jumps=0 $(align)-loops=0

cflags-$(CONFIG_MCRUSOE)	+= -march=i686 -falign-functions=0 -falign-jumps=0 -falign-loops=0

cflags-$(CONFIG_MEFFICEON)	+= -march=i686 $(call tune,pentium3) -falign-functions=0 -falign-jumps=0 -falign-loops=0

cflags-$(CONFIG_MWINCHIPC6)	+= $(call cc-option,-march=winchip-c6,-march=i586)

cflags-$(CONFIG_MWINCHIP3D)	+= $(call cc-option,-march=winchip2,-march=i586)

cflags-$(CONFIG_MCYRIXIII)	+= $(call cc-option,-march=c3,-march=i486) $(align)-functions=0 $(align)-jumps=0 $(align)-loops=0

cflags-$(CONFIG_MCYRIXIII)	+= $(call cc-option,-march=c3,-march=i486) -falign-functions=0 -falign-jumps=0 -falign-loops=0

cflags-$(CONFIG_MVIAC3_2)	+= $(call cc-option,-march=c3-2,-march=i686)

cflags-$(CONFIG_MVIAC7)		+= -march=i686

cflags-$(CONFIG_MCORE2)		+= -march=i686 $(call tune,core2)

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