xref: /openbmc/linux/arch/x86/Makefile (revision 842ed298) 
1# SPDX-License-Identifier: GPL-2.0
2# Unified Makefile for i386 and x86_64
3
4# select defconfig based on actual architecture
5ifeq ($(ARCH),x86)
6  ifeq ($(shell uname -m),x86_64)
7        KBUILD_DEFCONFIG := x86_64_defconfig
8  else
9        KBUILD_DEFCONFIG := i386_defconfig
10  endif
11else
12        KBUILD_DEFCONFIG := $(ARCH)_defconfig
13endif
14
15# For gcc stack alignment is specified with -mpreferred-stack-boundary,
16# clang has the option -mstack-alignment for that purpose.
17ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
18      cc_stack_align4 := -mpreferred-stack-boundary=2
19      cc_stack_align8 := -mpreferred-stack-boundary=3
20else ifneq ($(call cc-option, -mstack-alignment=16),)
21      cc_stack_align4 := -mstack-alignment=4
22      cc_stack_align8 := -mstack-alignment=8
23endif
24
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.
27REALMODE_CFLAGS	:= -m16 -g -Os -DDISABLE_BRANCH_PROFILING \
28		   -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
29		   -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
30		   -mno-mmx -mno-sse
31
32REALMODE_CFLAGS += -ffreestanding
33REALMODE_CFLAGS += -fno-stack-protector
34REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member)
35REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
36export REALMODE_CFLAGS
37
38# BITS is used as extension for files which are available in a 32 bit
39# and a 64 bit version to simplify shared Makefiles.
40# e.g.: obj-y += foo_$(BITS).o
41export BITS
42
43#
44# Prevent GCC from generating any FP code by mistake.
45#
46# This must happen before we try the -mpreferred-stack-boundary, see:
47#
48#    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
49#
50KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
51KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
52
53# Intel CET isn't enabled in the kernel
54KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
55
56ifeq ($(CONFIG_X86_32),y)
57        BITS := 32
58        UTS_MACHINE := i386
59        CHECKFLAGS += -D__i386__
60
61        biarch := $(call cc-option,-m32)
62        KBUILD_AFLAGS += $(biarch)
63        KBUILD_CFLAGS += $(biarch)
64
65        KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
66
67        # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
68        # with nonstandard options
69        KBUILD_CFLAGS += -fno-pic
70
71        # Align the stack to the register width instead of using the default
72        # alignment of 16 bytes. This reduces stack usage and the number of
73        # alignment instructions.
74        KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
75
76        # CPU-specific tuning. Anything which can be shared with UML should go here.
77        include arch/x86/Makefile_32.cpu
78        KBUILD_CFLAGS += $(cflags-y)
79
80        # temporary until string.h is fixed
81        KBUILD_CFLAGS += -ffreestanding
82else
83        BITS := 64
84        UTS_MACHINE := x86_64
85        CHECKFLAGS += -D__x86_64__
86
87        biarch := -m64
88        KBUILD_AFLAGS += -m64
89        KBUILD_CFLAGS += -m64
90
91        # Align jump targets to 1 byte, not the default 16 bytes:
92        KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
93
94        # Pack loops tightly as well:
95        KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
96
97        # Don't autogenerate traditional x87 instructions
98        KBUILD_CFLAGS += $(call cc-option,-mno-80387)
99        KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
100
101        # By default gcc and clang use a stack alignment of 16 bytes for x86.
102        # However the standard kernel entry on x86-64 leaves the stack on an
103        # 8-byte boundary. If the compiler isn't informed about the actual
104        # alignment it will generate extra alignment instructions for the
105        # default alignment which keep the stack *mis*aligned.
106        # Furthermore an alignment to the register width reduces stack usage
107        # and the number of alignment instructions.
108        KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
109
110	# Use -mskip-rax-setup if supported.
111	KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
112
113        # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
114        cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
115        cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
116
117        cflags-$(CONFIG_MCORE2) += \
118                $(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
119	cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
120		$(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
121        cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
122        KBUILD_CFLAGS += $(cflags-y)
123
124        KBUILD_CFLAGS += -mno-red-zone
125        KBUILD_CFLAGS += -mcmodel=kernel
126endif
127
128ifdef CONFIG_X86_X32
129	x32_ld_ok := $(call try-run,\
130			/bin/echo -e '1: .quad 1b' | \
131			$(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
132			$(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
133			$(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
134        ifeq ($(x32_ld_ok),y)
135                CONFIG_X86_X32_ABI := y
136                KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
137                KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
138        else
139                $(warning CONFIG_X86_X32 enabled but no binutils support)
140        endif
141endif
142export CONFIG_X86_X32_ABI
143
144#
145# If the function graph tracer is used with mcount instead of fentry,
146# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
147# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109)
148#
149ifdef CONFIG_FUNCTION_GRAPH_TRACER
150  ifndef CONFIG_HAVE_FENTRY
151	ACCUMULATE_OUTGOING_ARGS := 1
152  else
153    ifeq ($(call cc-option-yn, -mfentry), n)
154	ACCUMULATE_OUTGOING_ARGS := 1
155
156	# GCC ignores '-maccumulate-outgoing-args' when used with '-Os'.
157	# If '-Os' is enabled, disable it and print a warning.
158        ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
159          undefine CONFIG_CC_OPTIMIZE_FOR_SIZE
160          $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE.  Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.)
161        endif
162
163    endif
164  endif
165endif
166
167ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
168	# This compiler flag is not supported by Clang:
169	KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
170endif
171
172# Workaround for a gcc prelease that unfortunately was shipped in a suse release
173KBUILD_CFLAGS += -Wno-sign-compare
174#
175KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
176
177# Avoid indirect branches in kernel to deal with Spectre
178ifdef CONFIG_RETPOLINE
179  KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
180  # Additionally, avoid generating expensive indirect jumps which
181  # are subject to retpolines for small number of switch cases.
182  # clang turns off jump table generation by default when under
183  # retpoline builds, however, gcc does not for x86. This has
184  # only been fixed starting from gcc stable version 8.4.0 and
185  # onwards, but not for older ones. See gcc bug #86952.
186  ifndef CONFIG_CC_IS_CLANG
187    KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables)
188  endif
189endif
190
191KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
192
193ifdef CONFIG_X86_NEED_RELOCS
194LDFLAGS_vmlinux := --emit-relocs --discard-none
195else
196LDFLAGS_vmlinux :=
197endif
198
199#
200# The 64-bit kernel must be aligned to 2MB.  Pass -z max-page-size=0x200000 to
201# the linker to force 2MB page size regardless of the default page size used
202# by the linker.
203#
204ifdef CONFIG_X86_64
205LDFLAGS_vmlinux += -z max-page-size=0x200000
206endif
207
208
209archscripts: scripts_basic
210	$(Q)$(MAKE) $(build)=arch/x86/tools relocs
211
212###
213# Syscall table generation
214
215archheaders:
216	$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
217
218###
219# Kernel objects
220
221head-y := arch/x86/kernel/head_$(BITS).o
222head-y += arch/x86/kernel/head$(BITS).o
223head-y += arch/x86/kernel/ebda.o
224head-y += arch/x86/kernel/platform-quirks.o
225
226libs-y  += arch/x86/lib/
227
228# See arch/x86/Kbuild for content of core part of the kernel
229core-y += arch/x86/
230
231# drivers-y are linked after core-y
232drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
233drivers-$(CONFIG_PCI)            += arch/x86/pci/
234
235# must be linked after kernel/
236drivers-$(CONFIG_OPROFILE) += arch/x86/oprofile/
237
238# suspend and hibernation support
239drivers-$(CONFIG_PM) += arch/x86/power/
240
241drivers-$(CONFIG_FB) += arch/x86/video/
242
243####
244# boot loader support. Several targets are kept for legacy purposes
245
246boot := arch/x86/boot
247
248BOOT_TARGETS = bzdisk fdimage fdimage144 fdimage288 isoimage
249
250PHONY += bzImage $(BOOT_TARGETS)
251
252# Default kernel to build
253all: bzImage
254
255# KBUILD_IMAGE specify target image being built
256KBUILD_IMAGE := $(boot)/bzImage
257
258bzImage: vmlinux
259ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
260	$(Q)$(MAKE) $(build)=arch/x86/tools posttest
261endif
262	$(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
263	$(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
264	$(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
265
266$(BOOT_TARGETS): vmlinux
267	$(Q)$(MAKE) $(build)=$(boot) $@
268
269PHONY += install bzlilo
270install bzlilo:
271	$(Q)$(MAKE) $(build)=$(boot) $@
272
273PHONY += vdso_install
274vdso_install:
275	$(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
276
277archprepare: checkbin
278checkbin:
279ifndef CONFIG_CC_HAS_ASM_GOTO
280	@echo Compiler lacks asm-goto support.
281	@exit 1
282endif
283ifdef CONFIG_RETPOLINE
284ifeq ($(RETPOLINE_CFLAGS),)
285	@echo "You are building kernel with non-retpoline compiler." >&2
286	@echo "Please update your compiler." >&2
287	@false
288endif
289endif
290
291archclean:
292	$(Q)rm -rf $(objtree)/arch/i386
293	$(Q)rm -rf $(objtree)/arch/x86_64
294	$(Q)$(MAKE) $(clean)=$(boot)
295	$(Q)$(MAKE) $(clean)=arch/x86/tools
296
297define archhelp
298  echo  '* bzImage      - Compressed kernel image (arch/x86/boot/bzImage)'
299  echo  '  install      - Install kernel using'
300  echo  '                  (your) ~/bin/$(INSTALLKERNEL) or'
301  echo  '                  (distribution) /sbin/$(INSTALLKERNEL) or'
302  echo  '                  install to $$(INSTALL_PATH) and run lilo'
303  echo  '  fdimage      - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
304  echo  '  fdimage144   - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
305  echo  '  fdimage288   - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
306  echo  '  isoimage     - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
307  echo  '                  bzdisk/fdimage*/isoimage also accept:'
308  echo  '                  FDARGS="..."  arguments for the booted kernel'
309  echo  '                  FDINITRD=file initrd for the booted kernel'
310endef
311