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42e0e95474
One of the very few warnings I have in the current build comes from
arch/x86/boot/edd.c, where I get the following with a gcc9 build:
arch/x86/boot/edd.c: In function ‘query_edd’:
arch/x86/boot/edd.c:148:11: warning: taking address of packed member of ‘struct boot_params’ may result in an unaligned pointer value [-Waddress-of-packed-member]
148 | mbrptr = boot_params.edd_mbr_sig_buffer;
| ^~~~~~~~~~~
This warning triggers because we throw away all the CFLAGS and then make
a new set for REALMODE_CFLAGS, so the -Wno-address-of-packed-member we
added in the following commit is not present:
6f303d6053 ("gcc-9: silence 'address-of-packed-member' warning")
The simplest solution for now is to adjust the warning for this version
of CFLAGS as well, but it would definitely make sense to examine whether
REALMODE_CFLAGS could be derived from CFLAGS, so that it picks up changes
in the compiler flags environment automatically.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
333 lines
12 KiB
Makefile
333 lines
12 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# Unified Makefile for i386 and x86_64
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# select defconfig based on actual architecture
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ifeq ($(ARCH),x86)
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ifeq ($(shell uname -m),x86_64)
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KBUILD_DEFCONFIG := x86_64_defconfig
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else
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KBUILD_DEFCONFIG := i386_defconfig
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endif
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else
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KBUILD_DEFCONFIG := $(ARCH)_defconfig
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endif
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# For gcc stack alignment is specified with -mpreferred-stack-boundary,
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# clang has the option -mstack-alignment for that purpose.
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ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
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cc_stack_align4 := -mpreferred-stack-boundary=2
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cc_stack_align8 := -mpreferred-stack-boundary=3
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else ifneq ($(call cc-option, -mstack-alignment=16),)
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cc_stack_align4 := -mstack-alignment=4
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cc_stack_align8 := -mstack-alignment=8
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endif
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# How to compile the 16-bit code. Note we always compile for -march=i386;
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# that way we can complain to the user if the CPU is insufficient.
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#
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# The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For
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# older versions of GCC, include an *assembly* header to make sure that
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# gcc doesn't play any games behind our back.
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CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h
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M16_CFLAGS := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))
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REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING \
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-Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
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-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
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-mno-mmx -mno-sse
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REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding)
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REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector)
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REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member)
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REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
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export REALMODE_CFLAGS
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# BITS is used as extension for files which are available in a 32 bit
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# and a 64 bit version to simplify shared Makefiles.
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# e.g.: obj-y += foo_$(BITS).o
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export BITS
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ifdef CONFIG_X86_NEED_RELOCS
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LDFLAGS_vmlinux := --emit-relocs --discard-none
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endif
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#
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# Prevent GCC from generating any FP code by mistake.
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#
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# This must happen before we try the -mpreferred-stack-boundary, see:
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#
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
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#
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KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
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KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
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ifeq ($(CONFIG_X86_32),y)
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BITS := 32
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UTS_MACHINE := i386
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CHECKFLAGS += -D__i386__
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biarch := $(call cc-option,-m32)
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KBUILD_AFLAGS += $(biarch)
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KBUILD_CFLAGS += $(biarch)
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KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
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# Never want PIC in a 32-bit kernel, prevent breakage with GCC built
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# with nonstandard options
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KBUILD_CFLAGS += -fno-pic
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# Align the stack to the register width instead of using the default
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# alignment of 16 bytes. This reduces stack usage and the number of
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# alignment instructions.
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KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
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# CPU-specific tuning. Anything which can be shared with UML should go here.
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include arch/x86/Makefile_32.cpu
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KBUILD_CFLAGS += $(cflags-y)
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# temporary until string.h is fixed
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KBUILD_CFLAGS += -ffreestanding
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else
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BITS := 64
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UTS_MACHINE := x86_64
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CHECKFLAGS += -D__x86_64__
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biarch := -m64
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KBUILD_AFLAGS += -m64
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KBUILD_CFLAGS += -m64
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# Align jump targets to 1 byte, not the default 16 bytes:
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KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
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# Pack loops tightly as well:
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KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
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# Don't autogenerate traditional x87 instructions
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KBUILD_CFLAGS += $(call cc-option,-mno-80387)
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KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
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# By default gcc and clang use a stack alignment of 16 bytes for x86.
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# However the standard kernel entry on x86-64 leaves the stack on an
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# 8-byte boundary. If the compiler isn't informed about the actual
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# alignment it will generate extra alignment instructions for the
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# default alignment which keep the stack *mis*aligned.
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# Furthermore an alignment to the register width reduces stack usage
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# and the number of alignment instructions.
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KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
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# Use -mskip-rax-setup if supported.
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KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
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# FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
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cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
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cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
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cflags-$(CONFIG_MCORE2) += \
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$(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
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cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
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$(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
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cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
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KBUILD_CFLAGS += $(cflags-y)
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KBUILD_CFLAGS += -mno-red-zone
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KBUILD_CFLAGS += -mcmodel=kernel
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endif
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ifdef CONFIG_X86_X32
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x32_ld_ok := $(call try-run,\
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/bin/echo -e '1: .quad 1b' | \
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$(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
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$(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
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$(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
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ifeq ($(x32_ld_ok),y)
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CONFIG_X86_X32_ABI := y
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KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
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KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
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else
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$(warning CONFIG_X86_X32 enabled but no binutils support)
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endif
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endif
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export CONFIG_X86_X32_ABI
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#
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# If the function graph tracer is used with mcount instead of fentry,
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# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
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# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
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#
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ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ifndef CONFIG_HAVE_FENTRY
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ACCUMULATE_OUTGOING_ARGS := 1
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else
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ifeq ($(call cc-option-yn, -mfentry), n)
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ACCUMULATE_OUTGOING_ARGS := 1
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# GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
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# If '-Os' is enabled, disable it and print a warning.
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ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
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undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
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$(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE. Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
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endif
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endif
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endif
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endif
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ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
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# This compiler flag is not supported by Clang:
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KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
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endif
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# Stackpointer is addressed different for 32 bit and 64 bit x86
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sp-$(CONFIG_X86_32) := esp
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sp-$(CONFIG_X86_64) := rsp
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# do binutils support CFI?
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cfi := $(call as-instr,.cfi_startproc\n.cfi_rel_offset $(sp-y)$(comma)0\n.cfi_endproc,-DCONFIG_AS_CFI=1)
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# is .cfi_signal_frame supported too?
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cfi-sigframe := $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1)
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cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)
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# does binutils support specific instructions?
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asinstr += $(call as-instr,pshufb %xmm0$(comma)%xmm0,-DCONFIG_AS_SSSE3=1)
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avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1)
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avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)
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avx512_instr :=$(call as-instr,vpmovm2b %k1$(comma)%zmm5,-DCONFIG_AS_AVX512=1)
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sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=1)
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sha256_ni_instr :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA256_NI=1)
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KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr)
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KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr)
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KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
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#
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# The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
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# the linker to force 2MB page size regardless of the default page size used
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# by the linker.
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#
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ifdef CONFIG_X86_64
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KBUILD_LDFLAGS += $(call ld-option, -z max-page-size=0x200000)
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endif
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# Workaround for a gcc prelease that unfortunately was shipped in a suse release
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KBUILD_CFLAGS += -Wno-sign-compare
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#
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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# Avoid indirect branches in kernel to deal with Spectre
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ifdef CONFIG_RETPOLINE
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KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
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# Additionally, avoid generating expensive indirect jumps which
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# are subject to retpolines for small number of switch cases.
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# clang turns off jump table generation by default when under
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# retpoline builds, however, gcc does not for x86. This has
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# only been fixed starting from gcc stable version 8.4.0 and
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# onwards, but not for older ones. See gcc bug #86952.
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ifndef CONFIG_CC_IS_CLANG
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KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables)
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endif
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endif
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archscripts: scripts_basic
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$(Q)$(MAKE) $(build)=arch/x86/tools relocs
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###
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# Syscall table generation
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archheaders:
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$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
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###
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# Kernel objects
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head-y := arch/x86/kernel/head_$(BITS).o
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head-y += arch/x86/kernel/head$(BITS).o
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head-y += arch/x86/kernel/ebda.o
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head-y += arch/x86/kernel/platform-quirks.o
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libs-y += arch/x86/lib/
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# See arch/x86/Kbuild for content of core part of the kernel
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core-y += arch/x86/
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# drivers-y are linked after core-y
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drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
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drivers-$(CONFIG_PCI) += arch/x86/pci/
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# must be linked after kernel/
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drivers-$(CONFIG_OPROFILE) += arch/x86/oprofile/
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# suspend and hibernation support
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drivers-$(CONFIG_PM) += arch/x86/power/
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drivers-$(CONFIG_FB) += arch/x86/video/
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####
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# boot loader support. Several targets are kept for legacy purposes
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boot := arch/x86/boot
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BOOT_TARGETS = bzlilo bzdisk fdimage fdimage144 fdimage288 isoimage
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PHONY += bzImage $(BOOT_TARGETS)
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# Default kernel to build
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all: bzImage
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# KBUILD_IMAGE specify target image being built
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KBUILD_IMAGE := $(boot)/bzImage
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bzImage: vmlinux
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ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
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$(Q)$(MAKE) $(build)=arch/x86/tools posttest
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endif
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$(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
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$(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
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$(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
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$(BOOT_TARGETS): vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $@
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PHONY += install
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install:
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$(Q)$(MAKE) $(build)=$(boot) $@
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PHONY += vdso_install
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vdso_install:
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$(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
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archprepare: checkbin
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checkbin:
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ifndef CONFIG_CC_HAS_ASM_GOTO
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@echo Compiler lacks asm-goto support.
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@exit 1
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endif
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ifdef CONFIG_RETPOLINE
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ifeq ($(RETPOLINE_CFLAGS),)
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@echo "You are building kernel with non-retpoline compiler." >&2
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@echo "Please update your compiler." >&2
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@false
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endif
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endif
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archclean:
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$(Q)rm -rf $(objtree)/arch/i386
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$(Q)rm -rf $(objtree)/arch/x86_64
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$(Q)$(MAKE) $(clean)=$(boot)
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$(Q)$(MAKE) $(clean)=arch/x86/tools
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define archhelp
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echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
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echo ' install - Install kernel using'
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echo ' (your) ~/bin/$(INSTALLKERNEL) or'
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echo ' (distribution) /sbin/$(INSTALLKERNEL) or'
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echo ' install to $$(INSTALL_PATH) and run lilo'
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echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
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echo ' bzdisk/fdimage*/isoimage also accept:'
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echo ' FDARGS="..." arguments for the booted kernel'
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echo ' FDINITRD=file initrd for the booted kernel'
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endef
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