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 ($(call cc-option, -mstack-alignment=16),)
21 cc_stack_align4 := -mstack-alignment=4
22 cc_stack_align8 := -mstack-alignment=8
25 # How to compile the 16-bit code. Note we always compile for -march=i386;
26 # that way we can complain to the user if the CPU is insufficient.
28 # The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For
29 # older versions of GCC, include an *assembly* header to make sure that
30 # gcc doesn't play any games behind our back.
31 CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h
32 M16_CFLAGS := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))
34 REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING -D__DISABLE_EXPORTS \
35 -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
36 -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
37 -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
39 REALMODE_CFLAGS += -ffreestanding
40 REALMODE_CFLAGS += -fno-stack-protector
41 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member)
42 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
43 REALMODE_CFLAGS += $(CLANG_FLAGS)
44 export REALMODE_CFLAGS
46 # BITS is used as extension for files which are available in a 32 bit
47 # and a 64 bit version to simplify shared Makefiles.
48 # e.g.: obj-y += foo_$(BITS).o
52 # Prevent GCC from generating any FP code by mistake.
54 # This must happen before we try the -mpreferred-stack-boundary, see:
56 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
58 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
59 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
61 # Intel CET isn't enabled in the kernel
62 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
64 ifeq ($(CONFIG_X86_32),y)
67 CHECKFLAGS += -D__i386__
69 biarch := $(call cc-option,-m32)
70 KBUILD_AFLAGS += $(biarch)
71 KBUILD_CFLAGS += $(biarch)
73 KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
75 # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
76 # with nonstandard options
77 KBUILD_CFLAGS += -fno-pic
79 # Align the stack to the register width instead of using the default
80 # alignment of 16 bytes. This reduces stack usage and the number of
81 # alignment instructions.
82 KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
84 # CPU-specific tuning. Anything which can be shared with UML should go here.
85 include arch/x86/Makefile_32.cpu
86 KBUILD_CFLAGS += $(cflags-y)
88 # temporary until string.h is fixed
89 KBUILD_CFLAGS += -ffreestanding
91 ifeq ($(CONFIG_STACKPROTECTOR),y)
92 ifeq ($(CONFIG_SMP),y)
93 KBUILD_CFLAGS += -mstack-protector-guard-reg=fs -mstack-protector-guard-symbol=__stack_chk_guard
95 KBUILD_CFLAGS += -mstack-protector-guard=global
100 UTS_MACHINE := x86_64
101 CHECKFLAGS += -D__x86_64__
104 KBUILD_AFLAGS += -m64
105 KBUILD_CFLAGS += -m64
107 # Align jump targets to 1 byte, not the default 16 bytes:
108 KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
110 # Pack loops tightly as well:
111 KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
113 # Don't autogenerate traditional x87 instructions
114 KBUILD_CFLAGS += $(call cc-option,-mno-80387)
115 KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
117 # By default gcc and clang use a stack alignment of 16 bytes for x86.
118 # However the standard kernel entry on x86-64 leaves the stack on an
119 # 8-byte boundary. If the compiler isn't informed about the actual
120 # alignment it will generate extra alignment instructions for the
121 # default alignment which keep the stack *mis*aligned.
122 # Furthermore an alignment to the register width reduces stack usage
123 # and the number of alignment instructions.
124 KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
126 # Use -mskip-rax-setup if supported.
127 KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
129 # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
130 cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
131 cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
133 cflags-$(CONFIG_MCORE2) += \
134 $(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
135 cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
136 $(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
137 cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
138 KBUILD_CFLAGS += $(cflags-y)
140 KBUILD_CFLAGS += -mno-red-zone
141 KBUILD_CFLAGS += -mcmodel=kernel
145 x32_ld_ok := $(call try-run,\
146 /bin/echo -e '1: .quad 1b' | \
147 $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
148 $(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
149 $(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
150 ifeq ($(x32_ld_ok),y)
151 CONFIG_X86_X32_ABI := y
152 KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
153 KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
155 $(warning CONFIG_X86_X32 enabled but no binutils support)
158 export CONFIG_X86_X32_ABI
161 # If the function graph tracer is used with mcount instead of fentry,
162 # '-maccumulate-outgoing-args' is needed to prevent a GCC bug
163 # (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
165 ifdef CONFIG_FUNCTION_GRAPH_TRACER
166 ifndef CONFIG_HAVE_FENTRY
167 ACCUMULATE_OUTGOING_ARGS := 1
169 ifeq ($(call cc-option-yn, -mfentry), n)
170 ACCUMULATE_OUTGOING_ARGS := 1
172 # GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
173 # If '-Os' is enabled, disable it and print a warning.
174 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
175 undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
176 $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE. Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
183 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
184 # This compiler flag is not supported by Clang:
185 KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
188 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
189 KBUILD_CFLAGS += -Wno-sign-compare
191 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
193 # Avoid indirect branches in kernel to deal with Spectre
194 ifdef CONFIG_RETPOLINE
195 KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
196 # Additionally, avoid generating expensive indirect jumps which
197 # are subject to retpolines for small number of switch cases.
198 # clang turns off jump table generation by default when under
199 # retpoline builds, however, gcc does not for x86. This has
200 # only been fixed starting from gcc stable version 8.4.0 and
201 # onwards, but not for older ones. See gcc bug #86952.
202 ifndef CONFIG_CC_IS_CLANG
203 KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables)
208 KBUILD_CFLAGS += -mharden-sls=all
211 KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
213 ifdef CONFIG_X86_NEED_RELOCS
214 LDFLAGS_vmlinux := --emit-relocs --discard-none
220 # The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
221 # the linker to force 2MB page size regardless of the default page size used
225 LDFLAGS_vmlinux += -z max-page-size=0x200000
229 archscripts: scripts_basic
230 $(Q)$(MAKE) $(build)=arch/x86/tools relocs
233 # Syscall table generation
236 $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
241 head-y := arch/x86/kernel/head_$(BITS).o
242 head-y += arch/x86/kernel/head$(BITS).o
243 head-y += arch/x86/kernel/ebda.o
244 head-y += arch/x86/kernel/platform-quirks.o
246 libs-y += arch/x86/lib/
248 # See arch/x86/Kbuild for content of core part of the kernel
251 # drivers-y are linked after core-y
252 drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
253 drivers-$(CONFIG_PCI) += arch/x86/pci/
255 # must be linked after kernel/
256 drivers-$(CONFIG_OPROFILE) += arch/x86/oprofile/
258 # suspend and hibernation support
259 drivers-$(CONFIG_PM) += arch/x86/power/
261 drivers-$(CONFIG_FB) += arch/x86/video/
264 # boot loader support. Several targets are kept for legacy purposes
266 boot := arch/x86/boot
268 BOOT_TARGETS = bzdisk fdimage fdimage144 fdimage288 isoimage
270 PHONY += bzImage $(BOOT_TARGETS)
272 # Default kernel to build
275 # KBUILD_IMAGE specify target image being built
276 KBUILD_IMAGE := $(boot)/bzImage
279 ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
280 $(Q)$(MAKE) $(build)=arch/x86/tools posttest
282 $(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
283 $(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
284 $(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
286 $(BOOT_TARGETS): vmlinux
287 $(Q)$(MAKE) $(build)=$(boot) $@
289 PHONY += install bzlilo
291 $(Q)$(MAKE) $(build)=$(boot) $@
293 PHONY += vdso_install
295 $(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
297 archprepare: checkbin
299 ifndef CONFIG_CC_HAS_ASM_GOTO
300 @echo Compiler lacks asm-goto support.
303 ifdef CONFIG_RETPOLINE
304 ifeq ($(RETPOLINE_CFLAGS),)
305 @echo "You are building kernel with non-retpoline compiler." >&2
306 @echo "Please update your compiler." >&2
312 $(Q)rm -rf $(objtree)/arch/i386
313 $(Q)rm -rf $(objtree)/arch/x86_64
314 $(Q)$(MAKE) $(clean)=$(boot)
315 $(Q)$(MAKE) $(clean)=arch/x86/tools
318 echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
319 echo ' install - Install kernel using'
320 echo ' (your) ~/bin/$(INSTALLKERNEL) or'
321 echo ' (distribution) /sbin/$(INSTALLKERNEL) or'
322 echo ' install to $$(INSTALL_PATH) and run lilo'
323 echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
324 echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
325 echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
326 echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
327 echo ' bzdisk/fdimage*/isoimage also accept:'
328 echo ' FDARGS="..." arguments for the booted kernel'
329 echo ' FDINITRD=file initrd for the booted kernel'