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 \
35 -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
36 -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
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), $(cc_stack_align4))
43 export REALMODE_CFLAGS
45 # BITS is used as extension for files which are available in a 32 bit
46 # and a 64 bit version to simplify shared Makefiles.
47 # e.g.: obj-y += foo_$(BITS).o
51 # Prevent GCC from generating any FP code by mistake.
53 # This must happen before we try the -mpreferred-stack-boundary, see:
55 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
57 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
58 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
60 ifeq ($(CONFIG_X86_32),y)
63 CHECKFLAGS += -D__i386__
65 biarch := $(call cc-option,-m32)
66 KBUILD_AFLAGS += $(biarch)
67 KBUILD_CFLAGS += $(biarch)
69 KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
71 # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
72 # with nonstandard options
73 KBUILD_CFLAGS += -fno-pic
75 # Align the stack to the register width instead of using the default
76 # alignment of 16 bytes. This reduces stack usage and the number of
77 # alignment instructions.
78 KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
80 # CPU-specific tuning. Anything which can be shared with UML should go here.
81 include arch/x86/Makefile_32.cpu
82 KBUILD_CFLAGS += $(cflags-y)
84 # temporary until string.h is fixed
85 KBUILD_CFLAGS += -ffreestanding
89 CHECKFLAGS += -D__x86_64__
95 # Align jump targets to 1 byte, not the default 16 bytes:
96 KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
98 # Pack loops tightly as well:
99 KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
101 # Don't autogenerate traditional x87 instructions
102 KBUILD_CFLAGS += $(call cc-option,-mno-80387)
103 KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
105 # By default gcc and clang use a stack alignment of 16 bytes for x86.
106 # However the standard kernel entry on x86-64 leaves the stack on an
107 # 8-byte boundary. If the compiler isn't informed about the actual
108 # alignment it will generate extra alignment instructions for the
109 # default alignment which keep the stack *mis*aligned.
110 # Furthermore an alignment to the register width reduces stack usage
111 # and the number of alignment instructions.
112 KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
114 # Use -mskip-rax-setup if supported.
115 KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
117 # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
118 cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
119 cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
121 cflags-$(CONFIG_MCORE2) += \
122 $(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
123 cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
124 $(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
125 cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
126 KBUILD_CFLAGS += $(cflags-y)
128 KBUILD_CFLAGS += -mno-red-zone
129 KBUILD_CFLAGS += -mcmodel=kernel
133 x32_ld_ok := $(call try-run,\
134 /bin/echo -e '1: .quad 1b' | \
135 $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
136 $(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
137 $(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
138 ifeq ($(x32_ld_ok),y)
139 CONFIG_X86_X32_ABI := y
140 KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
141 KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
143 $(warning CONFIG_X86_X32 enabled but no binutils support)
146 export CONFIG_X86_X32_ABI
149 # If the function graph tracer is used with mcount instead of fentry,
150 # '-maccumulate-outgoing-args' is needed to prevent a GCC bug
151 # (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
153 ifdef CONFIG_FUNCTION_GRAPH_TRACER
154 ifndef CONFIG_HAVE_FENTRY
155 ACCUMULATE_OUTGOING_ARGS := 1
157 ifeq ($(call cc-option-yn, -mfentry), n)
158 ACCUMULATE_OUTGOING_ARGS := 1
160 # GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
161 # If '-Os' is enabled, disable it and print a warning.
162 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
163 undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
164 $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE. Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
171 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
172 # This compiler flag is not supported by Clang:
173 KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
176 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
177 KBUILD_CFLAGS += -Wno-sign-compare
179 KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
181 # Avoid indirect branches in kernel to deal with Spectre
182 ifdef CONFIG_RETPOLINE
183 KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
184 # Additionally, avoid generating expensive indirect jumps which
185 # are subject to retpolines for small number of switch cases.
186 # clang turns off jump table generation by default when under
187 # retpoline builds, however, gcc does not for x86. This has
188 # only been fixed starting from gcc stable version 8.4.0 and
189 # onwards, but not for older ones. See gcc bug #86952.
190 ifndef CONFIG_CC_IS_CLANG
191 KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables)
195 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
197 ifdef CONFIG_X86_NEED_RELOCS
198 LDFLAGS_vmlinux := --emit-relocs --discard-none
204 # The 64-bit kernel must be aligned to 2MB. Pass -z max-page-size=0x200000 to
205 # the linker to force 2MB page size regardless of the default page size used
209 LDFLAGS_vmlinux += -z max-page-size=0x200000
212 archscripts: scripts_basic
213 $(Q)$(MAKE) $(build)=arch/x86/tools relocs
216 # Syscall table generation
219 $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
224 head-y := arch/x86/kernel/head_$(BITS).o
225 head-y += arch/x86/kernel/head$(BITS).o
226 head-y += arch/x86/kernel/ebda.o
227 head-y += arch/x86/kernel/platform-quirks.o
229 libs-y += arch/x86/lib/
231 # See arch/x86/Kbuild for content of core part of the kernel
234 # drivers-y are linked after core-y
235 drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
236 drivers-$(CONFIG_PCI) += arch/x86/pci/
238 # must be linked after kernel/
239 drivers-$(CONFIG_OPROFILE) += arch/x86/oprofile/
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'
303 echo ' (your) ~/bin/$(INSTALLKERNEL) or'
304 echo ' (distribution) /sbin/$(INSTALLKERNEL) or'
305 echo ' install to $$(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'