linux-yocto/arch/x86/Makefile

SPDX-License-Identifier: GPL-2.0

Unified Makefile for i386 and x86_64

select defconfig based on actual architecture

ifeq ($(ARCH),x86) ifeq ($(shell uname -m),x86_64) KBUILD_DEFCONFIG := x86_64_defconfig else KBUILD_DEFCONFIG := i386_defconfig endif 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 ($(call cc-option, -mpreferred-stack-boundary=4),) cc_stack_align4 := -mpreferred-stack-boundary=2 cc_stack_align8 := -mpreferred-stack-boundary=3 else ifneq ($(call cc-option, -mstack-alignment=16),) cc_stack_align4 := -mstack-alignment=4 cc_stack_align8 := -mstack-alignment=8 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.

The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For

older versions of GCC, include an assembly header to make sure that

gcc doesn't play any games behind our back.

CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h M16_CFLAGS := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))

REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING
-Wall -Wstrict-prototypes -march=i386 -mregparm=3
-fno-strict-aliasing -fomit-frame-pointer -fno-pic
-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_align4)) export REALMODE_CFLAGS

BITS is used as extension for files which are available in a 32 bit

and a 64 bit version to simplify shared Makefiles.

e.g.: obj-y += foo_$(BITS).o

export BITS

ifdef CONFIG_X86_NEED_RELOCS LDFLAGS_vmlinux := --emit-relocs endif

Prevent GCC from generating any FP code by mistake.

This must happen before we try the -mpreferred-stack-boundary, see:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383

KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow KBUILD_CFLAGS += $(call cc-option,-mno-avx,)

ifeq ($(CONFIG_X86_32),y) BITS := 32 UTS_MACHINE := i386 CHECKFLAGS += -D__i386__

    biarch := $(call cc-option,-m32)
    KBUILD_AFLAGS += $(biarch)
    KBUILD_CFLAGS += $(biarch)

    KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return

    # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
    # with nonstandard options
    KBUILD_CFLAGS += -fno-pic

    # 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_align4))

    # CPU-specific tuning. Anything which can be shared with UML should go here.
    include arch/x86/Makefile_32.cpu
    KBUILD_CFLAGS += $(cflags-y)

    # temporary until string.h is fixed
    KBUILD_CFLAGS += -ffreestanding

else BITS := 64 UTS_MACHINE := x86_64 CHECKFLAGS += -D__x86_64__

    biarch := -m64
    KBUILD_AFLAGS += -m64
    KBUILD_CFLAGS += -m64

    # Align jump targets to 1 byte, not the default 16 bytes:
    KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)

    # Pack loops tightly as well:
    KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)

    # Don't autogenerate traditional x87 instructions
    KBUILD_CFLAGS += $(call cc-option,-mno-80387)
    KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)

    # 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_align8))

# Use -mskip-rax-setup if supported.
KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)

    # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
    cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
    cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)

    cflags-$(CONFIG_MCORE2) += \
            $(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
	$(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
    cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
    KBUILD_CFLAGS += $(cflags-y)

    KBUILD_CFLAGS += -mno-red-zone
    KBUILD_CFLAGS += -mcmodel=kernel

    # -funit-at-a-time shrinks the kernel .text considerably
    # unfortunately it makes reading oopses harder.
    KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)

endif

ifdef CONFIG_X86_X32 x32_ld_ok := $(call try-run,
/bin/echo -e '1: .quad 1b' |
$(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - &&
$(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" &&
$(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n) ifeq ($(x32_ld_ok),y) CONFIG_X86_X32_ABI := y KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI else $(warning CONFIG_X86_X32 enabled but no binutils support) endif endif export CONFIG_X86_X32_ABI

If the function graph tracer is used with mcount instead of fentry,

'-maccumulate-outgoing-args' is needed to prevent a GCC bug

(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)

ifdef CONFIG_FUNCTION_GRAPH_TRACER ifndef CONFIG_HAVE_FENTRY ACCUMULATE_OUTGOING_ARGS := 1 else ifeq ($(call cc-option-yn, -mfentry), n) ACCUMULATE_OUTGOING_ARGS := 1

# GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
# If '-Os' is enabled, disable it and print a warning.
    ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
      undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
      $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE.  Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
    endif

endif

endif endif

ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1) # This compiler flag is not supported by Clang: KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,) endif

Stackpointer is addressed different for 32 bit and 64 bit x86

sp-$(CONFIG_X86_32) := esp sp-$(CONFIG_X86_64) := rsp

do binutils support CFI?

cfi := $(call as-instr,.cfi_startproc\n.cfi_rel_offset $(sp-y)$(comma)0\n.cfi_endproc,-DCONFIG_AS_CFI=1)

is .cfi_signal_frame supported too?

cfi-sigframe := $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1) cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTIONS=1)

does binutils support specific instructions?

asinstr := $(call as-instr,fxsaveq (%rax),-DCONFIG_AS_FXSAVEQ=1) asinstr += $(call as-instr,pshufb %xmm0$(comma)%xmm0,-DCONFIG_AS_SSSE3=1) avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1) avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1) avx512_instr :=$(call as-instr,vpmovm2b %k1$(comma)%zmm5,-DCONFIG_AS_AVX512=1) sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=1) sha256_ni_instr :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA256_NI=1)

KBUILD_AFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) KBUILD_CFLAGS += $(cfi) $(cfi-sigframe) $(cfi-sections) $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr)

KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)

The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to

the linker to force 2MB page size regardless of the default page size used

by the linker.

ifdef CONFIG_X86_64 KBUILD_LDFLAGS += $(call ld-option, -z max-page-size=0x200000) endif

Workaround for a gcc prelease that unfortunately was shipped in a suse release

KBUILD_CFLAGS += -Wno-sign-compare

KBUILD_CFLAGS += -fno-asynchronous-unwind-tables

Avoid indirect branches in kernel to deal with Spectre

ifdef CONFIG_RETPOLINE ifeq ($(RETPOLINE_CFLAGS),) $(error You are building kernel with non-retpoline compiler, please update your compiler.) endif KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) endif

archscripts: scripts_basic $(Q)$(MAKE) $(build)=arch/x86/tools relocs

Syscall table generation

archheaders: $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all

archmacros: $(Q)$(MAKE) $(build)=arch/x86/kernel arch/x86/kernel/macros.s

ASM_MACRO_FLAGS = -Wa,arch/x86/kernel/macros.s export ASM_MACRO_FLAGS KBUILD_CFLAGS += $(ASM_MACRO_FLAGS)

Kernel objects

head-y := arch/x86/kernel/head_$(BITS).o head-y += arch/x86/kernel/head$(BITS).o head-y += arch/x86/kernel/ebda.o head-y += arch/x86/kernel/platform-quirks.o

libs-y += arch/x86/lib/

See arch/x86/Kbuild for content of core part of the kernel

core-y += arch/x86/

drivers-y are linked after core-y

drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/ drivers-$(CONFIG_PCI) += arch/x86/pci/

must be linked after kernel/

drivers-$(CONFIG_OPROFILE) += arch/x86/oprofile/

suspend and hibernation support

drivers-$(CONFIG_PM) += arch/x86/power/

drivers-$(CONFIG_FB) += arch/x86/video/

boot loader support. Several targets are kept for legacy purposes

boot := arch/x86/boot

BOOT_TARGETS = bzlilo bzdisk fdimage fdimage144 fdimage288 isoimage

PHONY += bzImage $(BOOT_TARGETS)

Default kernel to build

all: bzImage

KBUILD_IMAGE specify target image being built

KBUILD_IMAGE := $(boot)/bzImage

bzImage: vmlinux ifeq ($(CONFIG_X86_DECODER_SELFTEST),y) $(Q)$(MAKE) $(build)=arch/x86/tools posttest endif $(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE) $(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot $(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@

$(BOOT_TARGETS): vmlinux $(Q)$(MAKE) $(build)=$(boot) $@

PHONY += install install: $(Q)$(MAKE) $(build)=$(boot) $@

PHONY += vdso_install vdso_install: $(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@

archprepare: checkbin checkbin: ifndef CC_HAVE_ASM_GOTO @echo Compiler lacks asm-goto support. @exit 1 endif

archclean: $(Q)rm -rf $(objtree)/arch/i386 $(Q)rm -rf $(objtree)/arch/x86_64 $(Q)$(MAKE) $(clean)=$(boot) $(Q)$(MAKE) $(clean)=arch/x86/tools

define archhelp echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)' echo ' install - Install kernel using' echo ' (your) ~/bin/$(INSTALLKERNEL) or' echo ' (distribution) /sbin/$(INSTALLKERNEL) or' echo ' install to $$(INSTALL_PATH) and run lilo' echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)' echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)' echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)' echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)' echo ' bzdisk/fdimage*/isoimage also accept:' echo ' FDARGS="..." arguments for the booted kernel' echo ' FDINITRD=file initrd for the booted kernel' endef