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
26 RETHUNK_CFLAGS := -mfunction-return=thunk-extern
27 RETPOLINE_CFLAGS += $(RETHUNK_CFLAGS)
30 export RETPOLINE_CFLAGS
31 export RETPOLINE_VDSO_CFLAGS
33 # For gcc stack alignment is specified with -mpreferred-stack-boundary,
34 # clang has the option -mstack-alignment for that purpose.
35 ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
36 cc_stack_align4 := -mpreferred-stack-boundary=2
37 cc_stack_align8 := -mpreferred-stack-boundary=3
38 else ifneq ($(call cc-option, -mstack-alignment=16),)
39 cc_stack_align4 := -mstack-alignment=4
40 cc_stack_align8 := -mstack-alignment=8
43 # How to compile the 16-bit code. Note we always compile for -march=i386;
44 # that way we can complain to the user if the CPU is insufficient.
45 REALMODE_CFLAGS := -m16 -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
46 -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
47 -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
48 -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
50 REALMODE_CFLAGS += -ffreestanding
51 REALMODE_CFLAGS += -fno-stack-protector
52 REALMODE_CFLAGS += -Wno-address-of-packed-member
53 REALMODE_CFLAGS += $(cc_stack_align4)
54 REALMODE_CFLAGS += $(CLANG_FLAGS)
55 export REALMODE_CFLAGS
57 # BITS is used as extension for files which are available in a 32 bit
58 # and a 64 bit version to simplify shared Makefiles.
59 # e.g.: obj-y += foo_$(BITS).o
63 # Prevent GCC from generating any FP code by mistake.
65 # This must happen before we try the -mpreferred-stack-boundary, see:
67 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
69 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
71 ifeq ($(CONFIG_X86_KERNEL_IBT),y)
73 # Kernel IBT has S_CET.NOTRACK_EN=0, as such the compilers must not generate
74 # NOTRACK prefixes. Current generation compilers unconditionally employ NOTRACK
75 # for jump-tables, as such, disable jump-tables for now.
77 # (jump-tables are implicitly disabled by RETPOLINE)
79 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816
81 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables)
83 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
86 ifeq ($(CONFIG_X86_32),y)
89 CHECKFLAGS += -D__i386__
94 KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
96 # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
97 # with nonstandard options
98 KBUILD_CFLAGS += -fno-pic
100 # Align the stack to the register width instead of using the default
101 # alignment of 16 bytes. This reduces stack usage and the number of
102 # alignment instructions.
103 KBUILD_CFLAGS += $(cc_stack_align4)
105 # CPU-specific tuning. Anything which can be shared with UML should go here.
106 include $(srctree)/arch/x86/Makefile_32.cpu
107 KBUILD_CFLAGS += $(cflags-y)
109 # temporary until string.h is fixed
110 KBUILD_CFLAGS += -ffreestanding
112 ifeq ($(CONFIG_STACKPROTECTOR),y)
113 ifeq ($(CONFIG_SMP),y)
114 KBUILD_CFLAGS += -mstack-protector-guard-reg=fs -mstack-protector-guard-symbol=__stack_chk_guard
116 KBUILD_CFLAGS += -mstack-protector-guard=global
121 UTS_MACHINE := x86_64
122 CHECKFLAGS += -D__x86_64__
124 KBUILD_AFLAGS += -m64
125 KBUILD_CFLAGS += -m64
127 # Align jump targets to 1 byte, not the default 16 bytes:
128 KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
130 # Pack loops tightly as well:
131 KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
133 # Don't autogenerate traditional x87 instructions
134 KBUILD_CFLAGS += -mno-80387
135 KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
137 # By default gcc and clang use a stack alignment of 16 bytes for x86.
138 # However the standard kernel entry on x86-64 leaves the stack on an
139 # 8-byte boundary. If the compiler isn't informed about the actual
140 # alignment it will generate extra alignment instructions for the
141 # default alignment which keep the stack *mis*aligned.
142 # Furthermore an alignment to the register width reduces stack usage
143 # and the number of alignment instructions.
144 KBUILD_CFLAGS += $(cc_stack_align8)
146 # Use -mskip-rax-setup if supported.
147 KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
149 # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
150 cflags-$(CONFIG_MK8) += -march=k8
151 cflags-$(CONFIG_MPSC) += -march=nocona
152 cflags-$(CONFIG_MCORE2) += -march=core2
153 cflags-$(CONFIG_MATOM) += -march=atom
154 cflags-$(CONFIG_GENERIC_CPU) += -mtune=generic
155 KBUILD_CFLAGS += $(cflags-y)
157 KBUILD_CFLAGS += -mno-red-zone
158 KBUILD_CFLAGS += -mcmodel=kernel
162 # If the function graph tracer is used with mcount instead of fentry,
163 # '-maccumulate-outgoing-args' is needed to prevent a GCC bug
164 # (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
166 ifdef CONFIG_FUNCTION_GRAPH_TRACER
167 ifndef CONFIG_HAVE_FENTRY
168 ACCUMULATE_OUTGOING_ARGS := 1
172 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
173 # This compiler flag is not supported by Clang:
174 KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
177 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
178 KBUILD_CFLAGS += -Wno-sign-compare
180 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
182 # Avoid indirect branches in kernel to deal with Spectre
183 ifdef CONFIG_RETPOLINE
184 KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
185 # Additionally, avoid generating expensive indirect jumps which
186 # are subject to retpolines for small number of switch cases.
187 # clang turns off jump table generation by default when under
188 # retpoline builds, however, gcc does not for x86. This has
189 # only been fixed starting from gcc stable version 8.4.0 and
190 # onwards, but not for older ones. See gcc bug #86952.
191 ifndef CONFIG_CC_IS_CLANG
192 KBUILD_CFLAGS += -fno-jump-tables
197 KBUILD_CFLAGS += -mharden-sls=all
200 KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
202 ifdef CONFIG_LTO_CLANG
203 ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0)
204 KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
208 ifdef CONFIG_X86_NEED_RELOCS
209 LDFLAGS_vmlinux := --emit-relocs --discard-none
215 # The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
216 # the linker to force 2MB page size regardless of the default page size used
220 LDFLAGS_vmlinux += -z max-page-size=0x200000
224 archscripts: scripts_basic
225 $(Q)$(MAKE) $(build)=arch/x86/tools relocs
228 # Syscall table generation
231 $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
236 head-y := arch/x86/kernel/head_$(BITS).o
237 head-y += arch/x86/kernel/head$(BITS).o
238 head-y += arch/x86/kernel/ebda.o
239 head-y += arch/x86/kernel/platform-quirks.o
241 libs-y += arch/x86/lib/
243 # drivers-y are linked after core-y
244 drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
245 drivers-$(CONFIG_PCI) += arch/x86/pci/
247 # suspend and hibernation support
248 drivers-$(CONFIG_PM) += arch/x86/power/
250 drivers-$(CONFIG_FB) += arch/x86/video/
253 # boot loader support. Several targets are kept for legacy purposes
255 boot := arch/x86/boot
257 BOOT_TARGETS = bzdisk fdimage fdimage144 fdimage288 hdimage isoimage
259 PHONY += bzImage $(BOOT_TARGETS)
261 # Default kernel to build
264 # KBUILD_IMAGE specify target image being built
265 KBUILD_IMAGE := $(boot)/bzImage
268 ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
269 $(Q)$(MAKE) $(build)=arch/x86/tools posttest
271 $(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
272 $(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
273 $(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
275 $(BOOT_TARGETS): vmlinux
276 $(Q)$(MAKE) $(build)=$(boot) $@
282 PHONY += vdso_install
284 $(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
286 archprepare: checkbin
288 ifndef CONFIG_CC_HAS_ASM_GOTO
289 @echo Compiler lacks asm-goto support.
292 ifdef CONFIG_RETPOLINE
293 ifeq ($(RETPOLINE_CFLAGS),)
294 @echo "You are building kernel with non-retpoline compiler." >&2
295 @echo "Please update your compiler." >&2
301 $(Q)rm -rf $(objtree)/arch/i386
302 $(Q)rm -rf $(objtree)/arch/x86_64
305 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
306 echo ' install - Install kernel using (your) ~/bin/$(INSTALLKERNEL) or'
307 echo ' (distribution) /sbin/$(INSTALLKERNEL) or install to '
308 echo ' $$(INSTALL_PATH) and run lilo'
310 echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
311 echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
312 echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
313 echo ' hdimage - Create a BIOS/EFI hard disk image (arch/x86/boot/hdimage)'
314 echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
315 echo ' bzdisk/fdimage*/hdimage/isoimage also accept:'
316 echo ' FDARGS="..." arguments for the booted kernel'
317 echo ' FDINITRD=file initrd for the booted kernel'
319 echo ' kvm_guest.config - Enable Kconfig items for running this kernel as a KVM guest'
320 echo ' xen.config - Enable Kconfig items for running this kernel as a Xen guest'
321 echo ' x86_debug.config - Enable tip tree debugging options for testing'