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 := $(ARCH)_defconfig
15 # For gcc stack alignment is specified with -mpreferred-stack-boundary,
16 # clang has the option -mstack-alignment for that purpose.
17 ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
18 cc_stack_align4 := -mpreferred-stack-boundary=2
19 cc_stack_align8 := -mpreferred-stack-boundary=3
20 else ifneq ($(call cc-option, -mstack-alignment=16),)
21 cc_stack_align4 := -mstack-alignment=4
22 cc_stack_align8 := -mstack-alignment=8
25 # How to compile the 16-bit code. Note we always compile for -march=i386;
26 # that way we can complain to the user if the CPU is insufficient.
27 REALMODE_CFLAGS := -m16 -g -Os -DDISABLE_BRANCH_PROFILING \
28 -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
29 -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
32 REALMODE_CFLAGS += -ffreestanding
33 REALMODE_CFLAGS += -fno-stack-protector
34 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member)
35 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
36 REALMODE_CFLAGS += $(CLANG_FLAGS)
37 export REALMODE_CFLAGS
39 # BITS is used as extension for files which are available in a 32 bit
40 # and a 64 bit version to simplify shared Makefiles.
41 # e.g.: obj-y += foo_$(BITS).o
45 # Prevent GCC from generating any FP code by mistake.
47 # This must happen before we try the -mpreferred-stack-boundary, see:
49 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
51 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
52 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
54 # Intel CET isn't enabled in the kernel
55 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
57 ifeq ($(CONFIG_X86_32),y)
60 CHECKFLAGS += -D__i386__
62 biarch := $(call cc-option,-m32)
63 KBUILD_AFLAGS += $(biarch)
64 KBUILD_CFLAGS += $(biarch)
66 KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
68 # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
69 # with nonstandard options
70 KBUILD_CFLAGS += -fno-pic
72 # Align the stack to the register width instead of using the default
73 # alignment of 16 bytes. This reduces stack usage and the number of
74 # alignment instructions.
75 KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
77 # CPU-specific tuning. Anything which can be shared with UML should go here.
78 include arch/x86/Makefile_32.cpu
79 KBUILD_CFLAGS += $(cflags-y)
81 # temporary until string.h is fixed
82 KBUILD_CFLAGS += -ffreestanding
86 CHECKFLAGS += -D__x86_64__
92 # Align jump targets to 1 byte, not the default 16 bytes:
93 KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
95 # Pack loops tightly as well:
96 KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
98 # Don't autogenerate traditional x87 instructions
99 KBUILD_CFLAGS += $(call cc-option,-mno-80387)
100 KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
102 # By default gcc and clang use a stack alignment of 16 bytes for x86.
103 # However the standard kernel entry on x86-64 leaves the stack on an
104 # 8-byte boundary. If the compiler isn't informed about the actual
105 # alignment it will generate extra alignment instructions for the
106 # default alignment which keep the stack *mis*aligned.
107 # Furthermore an alignment to the register width reduces stack usage
108 # and the number of alignment instructions.
109 KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
111 # Use -mskip-rax-setup if supported.
112 KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
114 # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
115 cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
116 cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
118 cflags-$(CONFIG_MCORE2) += \
119 $(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
120 cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
121 $(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
122 cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
123 KBUILD_CFLAGS += $(cflags-y)
125 KBUILD_CFLAGS += -mno-red-zone
126 KBUILD_CFLAGS += -mcmodel=kernel
130 x32_ld_ok := $(call try-run,\
131 /bin/echo -e '1: .quad 1b' | \
132 $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
133 $(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
134 $(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
135 ifeq ($(x32_ld_ok),y)
136 CONFIG_X86_X32_ABI := y
137 KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
138 KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
140 $(warning CONFIG_X86_X32 enabled but no binutils support)
143 export CONFIG_X86_X32_ABI
146 # If the function graph tracer is used with mcount instead of fentry,
147 # '-maccumulate-outgoing-args' is needed to prevent a GCC bug
148 # (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
150 ifdef CONFIG_FUNCTION_GRAPH_TRACER
151 ifndef CONFIG_HAVE_FENTRY
152 ACCUMULATE_OUTGOING_ARGS := 1
154 ifeq ($(call cc-option-yn, -mfentry), n)
155 ACCUMULATE_OUTGOING_ARGS := 1
157 # GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
158 # If '-Os' is enabled, disable it and print a warning.
159 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
160 undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
161 $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE. Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
168 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
169 # This compiler flag is not supported by Clang:
170 KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
173 ifdef CONFIG_LTO_CLANG
174 KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \
175 -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
178 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
179 KBUILD_CFLAGS += -Wno-sign-compare
181 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
183 # Avoid indirect branches in kernel to deal with Spectre
184 ifdef CONFIG_RETPOLINE
185 KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
186 # Additionally, avoid generating expensive indirect jumps which
187 # are subject to retpolines for small number of switch cases.
188 # clang turns off jump table generation by default when under
189 # retpoline builds, however, gcc does not for x86. This has
190 # only been fixed starting from gcc stable version 8.4.0 and
191 # onwards, but not for older ones. See gcc bug #86952.
192 ifndef CONFIG_CC_IS_CLANG
193 KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables)
197 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
199 ifdef CONFIG_X86_NEED_RELOCS
200 LDFLAGS_vmlinux := --emit-relocs --discard-none
206 # The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
207 # the linker to force 2MB page size regardless of the default page size used
211 LDFLAGS_vmlinux += -z max-page-size=0x200000
215 archscripts: scripts_basic
216 $(Q)$(MAKE) $(build)=arch/x86/tools relocs
219 # Syscall table generation
222 $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
227 head-y := arch/x86/kernel/head_$(BITS).o
228 head-y += arch/x86/kernel/head$(BITS).o
229 head-y += arch/x86/kernel/ebda.o
230 head-y += arch/x86/kernel/platform-quirks.o
232 libs-y += arch/x86/lib/
234 # See arch/x86/Kbuild for content of core part of the kernel
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 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) $@
272 PHONY += install bzlilo
274 $(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
297 $(Q)$(MAKE) $(clean)=$(boot)
298 $(Q)$(MAKE) $(clean)=arch/x86/tools
301 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
302 echo ' install - Install kernel using (your) ~/bin/$(INSTALLKERNEL) or'
303 echo ' (distribution) /sbin/$(INSTALLKERNEL) or install to '
304 echo ' $$(INSTALL_PATH) and run lilo'
306 echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
307 echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
308 echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
309 echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
310 echo ' bzdisk/fdimage*/isoimage also accept:'
311 echo ' FDARGS="..." arguments for the booted kernel'
312 echo ' FDINITRD=file initrd for the booted kernel'
314 echo ' kvm_guest.config - Enable Kconfig items for running this kernel as a KVM guest'
315 echo ' xen.config - Enable Kconfig items for running this kernel as a Xen guest'