forked from luck/tmp_suning_uos_patched
131484c8da
So the dwarf2 annotations in low level assembly code have become an increasing hindrance: unreadable, messy macros mixed into some of the most security sensitive code paths of the Linux kernel. These debug info annotations don't even buy the upstream kernel anything: dwarf driven stack unwinding has caused problems in the past so it's out of tree, and the upstream kernel only uses the much more robust framepointers based stack unwinding method. In addition to that there's a steady, slow bitrot going on with these annotations, requiring frequent fixups. There's no tooling and no functionality upstream that keeps it correct. So burn down the sick forest, allowing new, healthier growth: 27 files changed, 350 insertions(+), 1101 deletions(-) Someone who has the willingness and time to do this properly can attempt to reintroduce dwarf debuginfo in x86 assembly code plus dwarf unwinding from first principles, with the following conditions: - it should be maximally readable, and maximally low-key to 'ordinary' code reading and maintenance. - find a build time method to insert dwarf annotations automatically in the most common cases, for pop/push instructions that manipulate the stack pointer. This could be done for example via a preprocessing step that just looks for common patterns - plus special annotations for the few cases where we want to depart from the default. We have hundreds of CFI annotations, so automating most of that makes sense. - it should come with build tooling checks that ensure that CFI annotations are sensible. We've seen such efforts from the framepointer side, and there's no reason it couldn't be done on the dwarf side. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jan Beulich <JBeulich@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
270 lines
8.9 KiB
Makefile
270 lines
8.9 KiB
Makefile
# Unified Makefile for i386 and x86_64
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# select defconfig based on actual architecture
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ifeq ($(ARCH),x86)
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ifeq ($(shell uname -m),x86_64)
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KBUILD_DEFCONFIG := x86_64_defconfig
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else
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KBUILD_DEFCONFIG := i386_defconfig
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endif
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else
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KBUILD_DEFCONFIG := $(ARCH)_defconfig
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endif
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# How to compile the 16-bit code. Note we always compile for -march=i386;
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# that way we can complain to the user if the CPU is insufficient.
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#
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# The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For
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# older versions of GCC, include an *assembly* header to make sure that
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# gcc doesn't play any games behind our back.
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CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h
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M16_CFLAGS := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))
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REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \
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-DDISABLE_BRANCH_PROFILING \
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-Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
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-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
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-mno-mmx -mno-sse \
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$(call cc-option, -ffreestanding) \
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$(call cc-option, -fno-stack-protector) \
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$(call cc-option, -mpreferred-stack-boundary=2)
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export REALMODE_CFLAGS
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# BITS is used as extension for files which are available in a 32 bit
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# and a 64 bit version to simplify shared Makefiles.
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# e.g.: obj-y += foo_$(BITS).o
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export BITS
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ifdef CONFIG_X86_NEED_RELOCS
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LDFLAGS_vmlinux := --emit-relocs
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endif
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ifeq ($(CONFIG_X86_32),y)
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BITS := 32
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UTS_MACHINE := i386
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CHECKFLAGS += -D__i386__
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biarch := $(call cc-option,-m32)
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KBUILD_AFLAGS += $(biarch)
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KBUILD_CFLAGS += $(biarch)
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KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
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# Never want PIC in a 32-bit kernel, prevent breakage with GCC built
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# with nonstandard options
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KBUILD_CFLAGS += -fno-pic
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# prevent gcc from keeping the stack 16 byte aligned
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KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=2)
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# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use
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# a lot more stack due to the lack of sharing of stacklots:
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KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0400, \
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$(call cc-option,-fno-unit-at-a-time))
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# CPU-specific tuning. Anything which can be shared with UML should go here.
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include arch/x86/Makefile_32.cpu
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KBUILD_CFLAGS += $(cflags-y)
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# temporary until string.h is fixed
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KBUILD_CFLAGS += -ffreestanding
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else
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BITS := 64
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UTS_MACHINE := x86_64
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CHECKFLAGS += -D__x86_64__ -m64
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biarch := -m64
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KBUILD_AFLAGS += -m64
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KBUILD_CFLAGS += -m64
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# Align jump targets to 1 byte, not the default 16 bytes:
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KBUILD_CFLAGS += -falign-jumps=1
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# Pack loops tightly as well:
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KBUILD_CFLAGS += -falign-loops=1
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# Don't autogenerate traditional x87 instructions
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KBUILD_CFLAGS += $(call cc-option,-mno-80387)
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KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
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# Use -mpreferred-stack-boundary=3 if supported.
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KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)
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# Use -mskip-rax-setup if supported.
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KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
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# FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
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cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
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cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
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cflags-$(CONFIG_MCORE2) += \
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$(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
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cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom) \
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$(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
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cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
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KBUILD_CFLAGS += $(cflags-y)
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KBUILD_CFLAGS += -mno-red-zone
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KBUILD_CFLAGS += -mcmodel=kernel
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# -funit-at-a-time shrinks the kernel .text considerably
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# unfortunately it makes reading oopses harder.
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KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
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# this works around some issues with generating unwind tables in older gccs
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# newer gccs do it by default
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KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args)
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endif
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# Make sure compiler does not have buggy stack-protector support.
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ifdef CONFIG_CC_STACKPROTECTOR
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cc_has_sp := $(srctree)/scripts/gcc-x86_$(BITS)-has-stack-protector.sh
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ifneq ($(shell $(CONFIG_SHELL) $(cc_has_sp) $(CC) $(KBUILD_CPPFLAGS) $(biarch)),y)
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$(warning stack-protector enabled but compiler support broken)
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endif
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endif
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ifdef CONFIG_X86_X32
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x32_ld_ok := $(call try-run,\
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/bin/echo -e '1: .quad 1b' | \
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$(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" - && \
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$(OBJCOPY) -O elf32-x86-64 "$$TMP" "$$TMPO" && \
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$(LD) -m elf32_x86_64 "$$TMPO" -o "$$TMP",y,n)
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ifeq ($(x32_ld_ok),y)
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CONFIG_X86_X32_ABI := y
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KBUILD_AFLAGS += -DCONFIG_X86_X32_ABI
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KBUILD_CFLAGS += -DCONFIG_X86_X32_ABI
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else
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$(warning CONFIG_X86_X32 enabled but no binutils support)
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endif
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endif
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export CONFIG_X86_X32_ABI
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# Don't unroll struct assignments with kmemcheck enabled
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ifeq ($(CONFIG_KMEMCHECK),y)
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KBUILD_CFLAGS += $(call cc-option,-fno-builtin-memcpy)
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endif
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# Stackpointer is addressed different for 32 bit and 64 bit x86
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sp-$(CONFIG_X86_32) := esp
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sp-$(CONFIG_X86_64) := rsp
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# does binutils support specific instructions?
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asinstr := $(call as-instr,fxsaveq (%rax),-DCONFIG_AS_FXSAVEQ=1)
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asinstr += $(call as-instr,pshufb %xmm0$(comma)%xmm0,-DCONFIG_AS_SSSE3=1)
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asinstr += $(call as-instr,crc32l %eax$(comma)%eax,-DCONFIG_AS_CRC32=1)
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avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1)
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avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)
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KBUILD_AFLAGS += $(asinstr) $(avx_instr) $(avx2_instr)
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KBUILD_CFLAGS += $(asinstr) $(avx_instr) $(avx2_instr)
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LDFLAGS := -m elf_$(UTS_MACHINE)
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# Speed up the build
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KBUILD_CFLAGS += -pipe
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# Workaround for a gcc prelease that unfortunately was shipped in a suse release
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KBUILD_CFLAGS += -Wno-sign-compare
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#
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KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
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# prevent gcc from generating any FP code by mistake
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KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
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KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
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KBUILD_CFLAGS += $(mflags-y)
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KBUILD_AFLAGS += $(mflags-y)
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archscripts: scripts_basic
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$(Q)$(MAKE) $(build)=arch/x86/tools relocs
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###
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# Syscall table generation
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archheaders:
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$(Q)$(MAKE) $(build)=arch/x86/syscalls all
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archprepare:
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ifeq ($(CONFIG_KEXEC_FILE),y)
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$(Q)$(MAKE) $(build)=arch/x86/purgatory arch/x86/purgatory/kexec-purgatory.c
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endif
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###
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# Kernel objects
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head-y := arch/x86/kernel/head_$(BITS).o
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head-y += arch/x86/kernel/head$(BITS).o
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head-y += arch/x86/kernel/head.o
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libs-y += arch/x86/lib/
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# See arch/x86/Kbuild for content of core part of the kernel
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core-y += arch/x86/
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# drivers-y are linked after core-y
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drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
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drivers-$(CONFIG_PCI) += arch/x86/pci/
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# must be linked after kernel/
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drivers-$(CONFIG_OPROFILE) += arch/x86/oprofile/
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# suspend and hibernation support
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drivers-$(CONFIG_PM) += arch/x86/power/
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drivers-$(CONFIG_FB) += arch/x86/video/
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####
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# boot loader support. Several targets are kept for legacy purposes
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boot := arch/x86/boot
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BOOT_TARGETS = bzlilo bzdisk fdimage fdimage144 fdimage288 isoimage
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PHONY += bzImage $(BOOT_TARGETS)
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# Default kernel to build
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all: bzImage
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# KBUILD_IMAGE specify target image being built
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KBUILD_IMAGE := $(boot)/bzImage
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bzImage: vmlinux
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ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
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$(Q)$(MAKE) $(build)=arch/x86/tools posttest
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endif
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$(Q)$(MAKE) $(build)=$(boot) $(KBUILD_IMAGE)
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$(Q)mkdir -p $(objtree)/arch/$(UTS_MACHINE)/boot
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$(Q)ln -fsn ../../x86/boot/bzImage $(objtree)/arch/$(UTS_MACHINE)/boot/$@
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$(BOOT_TARGETS): vmlinux
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$(Q)$(MAKE) $(build)=$(boot) $@
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PHONY += install
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install:
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$(Q)$(MAKE) $(build)=$(boot) $@
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PHONY += vdso_install
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vdso_install:
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$(Q)$(MAKE) $(build)=arch/x86/vdso $@
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archclean:
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$(Q)rm -rf $(objtree)/arch/i386
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$(Q)rm -rf $(objtree)/arch/x86_64
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$(Q)$(MAKE) $(clean)=$(boot)
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$(Q)$(MAKE) $(clean)=arch/x86/tools
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$(Q)$(MAKE) $(clean)=arch/x86/purgatory
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define archhelp
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echo '* bzImage - Compressed kernel image (arch/x86/boot/bzImage)'
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echo ' install - Install kernel using'
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echo ' (your) ~/bin/$(INSTALLKERNEL) or'
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echo ' (distribution) /sbin/$(INSTALLKERNEL) or'
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echo ' install to $$(INSTALL_PATH) and run lilo'
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echo ' fdimage - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' fdimage144 - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' fdimage288 - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)'
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echo ' isoimage - Create a boot CD-ROM image (arch/x86/boot/image.iso)'
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echo ' bzdisk/fdimage*/isoimage also accept:'
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echo ' FDARGS="..." arguments for the booted kernel'
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echo ' FDINITRD=file initrd for the booted kernel'
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endef
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