1 # SPDX-License-Identifier: GPL-2.0
2 # Unified Makefile for i386 and x86_64
4 # select defconfig based on actual architecture
6 ifeq ($(shell uname -m),x86_64)
7 KBUILD_DEFCONFIG := x86_64_defconfig
9 KBUILD_DEFCONFIG := i386_defconfig
12 KBUILD_DEFCONFIG := $(ARCH)_defconfig
15 ifdef CONFIG_CC_IS_GCC
16 RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
17 RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch-cs-prefix)
18 RETPOLINE_VDSO_CFLAGS := $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register)
20 ifdef CONFIG_CC_IS_CLANG
21 RETPOLINE_CFLAGS := -mretpoline-external-thunk
22 RETPOLINE_VDSO_CFLAGS := -mretpoline
24 export RETPOLINE_CFLAGS
25 export RETPOLINE_VDSO_CFLAGS
27 # For gcc stack alignment is specified with -mpreferred-stack-boundary,
28 # clang has the option -mstack-alignment for that purpose.
29 ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
30 cc_stack_align4 := -mpreferred-stack-boundary=2
31 cc_stack_align8 := -mpreferred-stack-boundary=3
32 else ifneq ($(call cc-option, -mstack-alignment=16),)
33 cc_stack_align4 := -mstack-alignment=4
34 cc_stack_align8 := -mstack-alignment=8
37 # How to compile the 16-bit code. Note we always compile for -march=i386;
38 # that way we can complain to the user if the CPU is insufficient.
39 REALMODE_CFLAGS := -m16 -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
40 -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
41 -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
42 -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
44 REALMODE_CFLAGS += -ffreestanding
45 REALMODE_CFLAGS += -fno-stack-protector
46 REALMODE_CFLAGS += -Wno-address-of-packed-member
47 REALMODE_CFLAGS += $(cc_stack_align4)
48 REALMODE_CFLAGS += $(CLANG_FLAGS)
49 export REALMODE_CFLAGS
51 # BITS is used as extension for files which are available in a 32 bit
52 # and a 64 bit version to simplify shared Makefiles.
53 # e.g.: obj-y += foo_$(BITS).o
57 # Prevent GCC from generating any FP code by mistake.
59 # This must happen before we try the -mpreferred-stack-boundary, see:
61 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
63 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
65 ifeq ($(CONFIG_X86_KERNEL_IBT),y)
67 # Kernel IBT has S_CET.NOTRACK_EN=0, as such the compilers must not generate
68 # NOTRACK prefixes. Current generation compilers unconditionally employ NOTRACK
69 # for jump-tables, as such, disable jump-tables for now.
71 # (jump-tables are implicitly disabled by RETPOLINE)
73 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816
75 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables)
77 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
80 ifeq ($(CONFIG_X86_32),y)
83 CHECKFLAGS += -D__i386__
88 KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
90 # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
91 # with nonstandard options
92 KBUILD_CFLAGS += -fno-pic
94 # Align the stack to the register width instead of using the default
95 # alignment of 16 bytes. This reduces stack usage and the number of
96 # alignment instructions.
97 KBUILD_CFLAGS += $(cc_stack_align4)
99 # CPU-specific tuning. Anything which can be shared with UML should go here.
100 include $(srctree)/arch/x86/Makefile_32.cpu
101 KBUILD_CFLAGS += $(cflags-y)
103 # temporary until string.h is fixed
104 KBUILD_CFLAGS += -ffreestanding
106 ifeq ($(CONFIG_STACKPROTECTOR),y)
107 ifeq ($(CONFIG_SMP),y)
108 KBUILD_CFLAGS += -mstack-protector-guard-reg=fs -mstack-protector-guard-symbol=__stack_chk_guard
110 KBUILD_CFLAGS += -mstack-protector-guard=global
115 UTS_MACHINE := x86_64
116 CHECKFLAGS += -D__x86_64__
118 KBUILD_AFLAGS += -m64
119 KBUILD_CFLAGS += -m64
121 # Align jump targets to 1 byte, not the default 16 bytes:
122 KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
124 # Pack loops tightly as well:
125 KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
127 # Don't autogenerate traditional x87 instructions
128 KBUILD_CFLAGS += -mno-80387
129 KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
131 # By default gcc and clang use a stack alignment of 16 bytes for x86.
132 # However the standard kernel entry on x86-64 leaves the stack on an
133 # 8-byte boundary. If the compiler isn't informed about the actual
134 # alignment it will generate extra alignment instructions for the
135 # default alignment which keep the stack *mis*aligned.
136 # Furthermore an alignment to the register width reduces stack usage
137 # and the number of alignment instructions.
138 KBUILD_CFLAGS += $(cc_stack_align8)
140 # Use -mskip-rax-setup if supported.
141 KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
143 # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
144 cflags-$(CONFIG_MK8) += -march=k8
145 cflags-$(CONFIG_MPSC) += -march=nocona
146 cflags-$(CONFIG_MCORE2) += -march=core2
147 cflags-$(CONFIG_MATOM) += -march=atom
148 cflags-$(CONFIG_GENERIC_CPU) += -mtune=generic
149 KBUILD_CFLAGS += $(cflags-y)
151 KBUILD_CFLAGS += -mno-red-zone
152 KBUILD_CFLAGS += -mcmodel=kernel
156 # If the function graph tracer is used with mcount instead of fentry,
157 # '-maccumulate-outgoing-args' is needed to prevent a GCC bug
158 # (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
160 ifdef CONFIG_FUNCTION_GRAPH_TRACER
161 ifndef CONFIG_HAVE_FENTRY
162 ACCUMULATE_OUTGOING_ARGS := 1
166 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
167 # This compiler flag is not supported by Clang:
168 KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
171 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
172 KBUILD_CFLAGS += -Wno-sign-compare
174 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
176 # Avoid indirect branches in kernel to deal with Spectre
177 ifdef CONFIG_RETPOLINE
178 KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
179 # Additionally, avoid generating expensive indirect jumps which
180 # are subject to retpolines for small number of switch cases.
181 # clang turns off jump table generation by default when under
182 # retpoline builds, however, gcc does not for x86. This has
183 # only been fixed starting from gcc stable version 8.4.0 and
184 # onwards, but not for older ones. See gcc bug #86952.
185 ifndef CONFIG_CC_IS_CLANG
186 KBUILD_CFLAGS += -fno-jump-tables
191 KBUILD_CFLAGS += -mharden-sls=all
194 KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
196 ifdef CONFIG_LTO_CLANG
197 ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
198 KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
202 ifdef CONFIG_X86_NEED_RELOCS
203 LDFLAGS_vmlinux := --emit-relocs --discard-none
209 # The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
210 # the linker to force 2MB page size regardless of the default page size used
214 LDFLAGS_vmlinux += -z max-page-size=0x200000
218 archscripts: scripts_basic
219 $(Q)$(MAKE) $(build)=arch/x86/tools relocs
222 # Syscall table generation
225 $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
230 head-y := arch/x86/kernel/head_$(BITS).o
231 head-y += arch/x86/kernel/head$(BITS).o
232 head-y += arch/x86/kernel/ebda.o
233 head-y += arch/x86/kernel/platform-quirks.o
235 libs-y += arch/x86/lib/
237 # drivers-y are linked after core-y
238 drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
239 drivers-$(CONFIG_PCI) += arch/x86/pci/
241 # suspend and hibernation support
242 drivers-$(CONFIG_PM) += arch/x86/power/
244 drivers-$(CONFIG_FB) += arch/x86/video/
247 # boot loader support. Several targets are kept for legacy purposes
249 boot := arch/x86/boot
251 BOOT_TARGETS = bzdisk fdimage fdimage144 fdimage288 hdimage isoimage
253 PHONY += bzImage $(BOOT_TARGETS)
255 # Default kernel to build
258 # KBUILD_IMAGE specify target image being built
259 KBUILD_IMAGE := $(boot)/bzImage
262 ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
263 $(Q)$(MAKE) $(build)=arch/x86/tools posttest
265 $(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
266 $(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
267 $(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
269 $(BOOT_TARGETS): vmlinux
270 $(Q)$(MAKE) $(build)=$(boot) $@
276 PHONY += vdso_install
278 $(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
280 archprepare: checkbin
282 ifndef CONFIG_CC_HAS_ASM_GOTO
283 @echo Compiler lacks asm-goto support.
286 ifdef CONFIG_RETPOLINE
287 ifeq ($(RETPOLINE_CFLAGS),)
288 @echo "You are building kernel with non-retpoline compiler." >&2
289 @echo "Please update your compiler." >&2
295 $(Q)rm -rf $(objtree)/arch/i386
296 $(Q)rm -rf $(objtree)/arch/x86_64
299 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
300 echo ' install - Install kernel using (your) ~/bin/$(INSTALLKERNEL) or'
301 echo ' (distribution) /sbin/$(INSTALLKERNEL) or install to '
302 echo ' $$(INSTALL_PATH) and run lilo'
304 echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
305 echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
306 echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
307 echo ' hdimage - Create a BIOS/EFI hard disk image (arch/x86/boot/hdimage)'
308 echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
309 echo ' bzdisk/fdimage*/hdimage/isoimage also accept:'
310 echo ' FDARGS="..." arguments for the booted kernel'
311 echo ' FDINITRD=file initrd for the booted kernel'
313 echo ' kvm_guest.config - Enable Kconfig items for running this kernel as a KVM guest'
314 echo ' xen.config - Enable Kconfig items for running this kernel as a Xen guest'
315 echo ' x86_debug.config - Enable tip tree debugging options for testing'