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Currently, the "run_size" variable holds the total kernel size (size of code plus brk and bss) and is calculated via the shell script arch/x86/tools/calc_run_size.sh. It gets the file offset and mem size of the .bss and .brk sections from the vmlinux, and adds them as follows: run_size = $(( $offsetA + $sizeA + $sizeB )) However, this is not correct (it is too large). To illustrate, here's a walk-through of the script's calculation, compared to the correct way to find it. First, offsetA is found as the starting address of the first .bss or .brk section seen in the ELF file. The sizeA and sizeB values are the respective section sizes. [bhe@x1 linux]$ objdump -h vmlinux vmlinux: file format elf64-x86-64 Sections: Idx Name Size VMA LMA File off Algn 27 .bss 00170000 ffffffff81ec8000 0000000001ec8000 012c8000 2**12 ALLOC 28 .brk 00027000 ffffffff82038000 0000000002038000 012c8000 2**0 ALLOC Here, offsetA is 0x012c8000, with sizeA at 0x00170000 and sizeB at 0x00027000. The resulting run_size is 0x145f000: 0x012c8000 + 0x00170000 + 0x00027000 = 0x145f000 However, if we instead examine the ELF LOAD program headers, we see a different picture. [bhe@x1 linux]$ readelf -l vmlinux Elf file type is EXEC (Executable file) Entry point 0x1000000 There are 5 program headers, starting at offset 64 Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align LOAD 0x0000000000200000 0xffffffff81000000 0x0000000001000000 0x0000000000b5e000 0x0000000000b5e000 R E 200000 LOAD 0x0000000000e00000 0xffffffff81c00000 0x0000000001c00000 0x0000000000145000 0x0000000000145000 RW 200000 LOAD 0x0000000001000000 0x0000000000000000 0x0000000001d45000 0x0000000000018158 0x0000000000018158 RW 200000 LOAD 0x000000000115e000 0xffffffff81d5e000 0x0000000001d5e000 0x000000000016a000 0x0000000000301000 RWE 200000 NOTE 0x000000000099bcac 0xffffffff8179bcac 0x000000000179bcac 0x00000000000001bc 0x00000000000001bc 4 Section to Segment mapping: Segment Sections... 00 .text .notes __ex_table .rodata __bug_table .pci_fixup .tracedata __ksymtab __ksymtab_gpl __ksymtab_strings __init_rodata __param __modver 01 .data .vvar 02 .data..percpu 03 .init.text .init.data .x86_cpu_dev.init .parainstructions .altinstructions .altinstr_replacement .iommu_table .apicdrivers .exit.text .smp_locks .bss .brk 04 .notes As mentioned, run_size needs to be the size of the running kernel including .bss and .brk. We can see from the Section/Segment mapping above that .bss and .brk are included in segment 03 (which corresponds to the final LOAD program header). To find the run_size, we calculate the end of the LOAD segment from its PhysAddr start (0x0000000001d5e000) and its MemSiz (0x0000000000301000), minus the physical load address of the kernel (the first LOAD segment's PhysAddr: 0x0000000001000000). The resulting run_size is 0x105f000: 0x0000000001d5e000 + 0x0000000000301000 - 0x0000000001000000 = 0x105f000 So, from this we can see that the existing run_size calculation is 0x400000 too high. And, as it turns out, the correct run_size is actually equal to VO_end - VO_text, which is certainly easier to calculate. _end: 0xffffffff8205f000 _text:0xffffffff81000000 0xffffffff8205f000 - 0xffffffff81000000 = 0x105f000 As a result, run_size is a simple constant, so we don't need to pass it around; we already have voffset.h for such things. We can share voffset.h between misc.c and header.S instead of getting run_size in other ways. This patch moves voffset.h creation code to boot/compressed/Makefile, and switches misc.c to use the VO_end - VO_text calculation for run_size. Dependence before: boot/header.S ==> boot/voffset.h ==> vmlinux boot/header.S ==> compressed/vmlinux ==> compressed/misc.c Dependence after: boot/header.S ==> compressed/vmlinux ==> compressed/misc.c ==> boot/voffset.h ==> vmlinux Signed-off-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Baoquan He <bhe@redhat.com> [ Rewrote the changelog. ] Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Young <dyoung@redhat.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Junjie Mao <eternal.n08@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: lasse.collin@tukaani.org Fixes: e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd") Link: http://lkml.kernel.org/r/1461888548-32439-5-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
190 lines
6.4 KiB
Makefile
190 lines
6.4 KiB
Makefile
#
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# arch/x86/boot/Makefile
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#
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# This file is subject to the terms and conditions of the GNU General Public
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# License. See the file "COPYING" in the main directory of this archive
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# for more details.
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#
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# Copyright (C) 1994 by Linus Torvalds
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# Changed by many, many contributors over the years.
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#
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KASAN_SANITIZE := n
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OBJECT_FILES_NON_STANDARD := y
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# Kernel does not boot with kcov instrumentation here.
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# One of the problems observed was insertion of __sanitizer_cov_trace_pc()
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# callback into middle of per-cpu data enabling code. Thus the callback observed
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# inconsistent state and crashed. We are interested mostly in syscall coverage,
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# so boot code is not interesting anyway.
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KCOV_INSTRUMENT := n
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# If you want to preset the SVGA mode, uncomment the next line and
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# set SVGA_MODE to whatever number you want.
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# Set it to -DSVGA_MODE=NORMAL_VGA if you just want the EGA/VGA mode.
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# The number is the same as you would ordinarily press at bootup.
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SVGA_MODE := -DSVGA_MODE=NORMAL_VGA
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targets := vmlinux.bin setup.bin setup.elf bzImage
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targets += fdimage fdimage144 fdimage288 image.iso mtools.conf
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subdir- := compressed
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setup-y += a20.o bioscall.o cmdline.o copy.o cpu.o cpuflags.o cpucheck.o
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setup-y += early_serial_console.o edd.o header.o main.o memory.o
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setup-y += pm.o pmjump.o printf.o regs.o string.o tty.o video.o
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setup-y += video-mode.o version.o
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setup-$(CONFIG_X86_APM_BOOT) += apm.o
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# The link order of the video-*.o modules can matter. In particular,
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# video-vga.o *must* be listed first, followed by video-vesa.o.
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# Hardware-specific drivers should follow in the order they should be
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# probed, and video-bios.o should typically be last.
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setup-y += video-vga.o
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setup-y += video-vesa.o
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setup-y += video-bios.o
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targets += $(setup-y)
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hostprogs-y := tools/build
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hostprogs-$(CONFIG_X86_FEATURE_NAMES) += mkcpustr
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HOST_EXTRACFLAGS += -I$(srctree)/tools/include \
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-include include/generated/autoconf.h \
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-D__EXPORTED_HEADERS__
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ifdef CONFIG_X86_FEATURE_NAMES
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$(obj)/cpu.o: $(obj)/cpustr.h
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quiet_cmd_cpustr = CPUSTR $@
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cmd_cpustr = $(obj)/mkcpustr > $@
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targets += cpustr.h
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$(obj)/cpustr.h: $(obj)/mkcpustr FORCE
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$(call if_changed,cpustr)
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endif
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clean-files += cpustr.h
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# ---------------------------------------------------------------------------
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KBUILD_CFLAGS := $(USERINCLUDE) $(REALMODE_CFLAGS) -D_SETUP
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KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
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GCOV_PROFILE := n
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UBSAN_SANITIZE := n
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$(obj)/bzImage: asflags-y := $(SVGA_MODE)
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quiet_cmd_image = BUILD $@
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cmd_image = $(obj)/tools/build $(obj)/setup.bin $(obj)/vmlinux.bin \
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$(obj)/zoffset.h $@
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$(obj)/bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin $(obj)/tools/build FORCE
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$(call if_changed,image)
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@echo 'Kernel: $@ is ready' ' (#'`cat .version`')'
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OBJCOPYFLAGS_vmlinux.bin := -O binary -R .note -R .comment -S
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$(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
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$(call if_changed,objcopy)
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SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
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sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|input_data\|_end\|_ehead\|_text\|z_.*\)$$/\#define ZO_\2 0x\1/p'
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quiet_cmd_zoffset = ZOFFSET $@
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cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@
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targets += zoffset.h
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$(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE
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$(call if_changed,zoffset)
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AFLAGS_header.o += -I$(obj)
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$(obj)/header.o: $(obj)/zoffset.h
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LDFLAGS_setup.elf := -T
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$(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
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$(call if_changed,ld)
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OBJCOPYFLAGS_setup.bin := -O binary
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$(obj)/setup.bin: $(obj)/setup.elf FORCE
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$(call if_changed,objcopy)
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$(obj)/compressed/vmlinux: FORCE
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$(Q)$(MAKE) $(build)=$(obj)/compressed $@
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# Set this if you want to pass append arguments to the
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# bzdisk/fdimage/isoimage kernel
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FDARGS =
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# Set this if you want an initrd included with the
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# bzdisk/fdimage/isoimage kernel
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FDINITRD =
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image_cmdline = default linux $(FDARGS) $(if $(FDINITRD),initrd=initrd.img,)
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$(obj)/mtools.conf: $(src)/mtools.conf.in
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sed -e 's|@OBJ@|$(obj)|g' < $< > $@
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# This requires write access to /dev/fd0
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bzdisk: $(obj)/bzImage $(obj)/mtools.conf
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MTOOLSRC=$(obj)/mtools.conf mformat a: ; sync
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syslinux /dev/fd0 ; sync
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echo '$(image_cmdline)' | \
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MTOOLSRC=$(src)/mtools.conf mcopy - a:syslinux.cfg
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if [ -f '$(FDINITRD)' ] ; then \
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MTOOLSRC=$(obj)/mtools.conf mcopy '$(FDINITRD)' a:initrd.img ; \
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fi
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MTOOLSRC=$(obj)/mtools.conf mcopy $(obj)/bzImage a:linux ; sync
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# These require being root or having syslinux 2.02 or higher installed
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fdimage fdimage144: $(obj)/bzImage $(obj)/mtools.conf
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dd if=/dev/zero of=$(obj)/fdimage bs=1024 count=1440
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MTOOLSRC=$(obj)/mtools.conf mformat v: ; sync
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syslinux $(obj)/fdimage ; sync
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echo '$(image_cmdline)' | \
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MTOOLSRC=$(obj)/mtools.conf mcopy - v:syslinux.cfg
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if [ -f '$(FDINITRD)' ] ; then \
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MTOOLSRC=$(obj)/mtools.conf mcopy '$(FDINITRD)' v:initrd.img ; \
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fi
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MTOOLSRC=$(obj)/mtools.conf mcopy $(obj)/bzImage v:linux ; sync
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fdimage288: $(obj)/bzImage $(obj)/mtools.conf
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dd if=/dev/zero of=$(obj)/fdimage bs=1024 count=2880
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MTOOLSRC=$(obj)/mtools.conf mformat w: ; sync
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syslinux $(obj)/fdimage ; sync
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echo '$(image_cmdline)' | \
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MTOOLSRC=$(obj)/mtools.conf mcopy - w:syslinux.cfg
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if [ -f '$(FDINITRD)' ] ; then \
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MTOOLSRC=$(obj)/mtools.conf mcopy '$(FDINITRD)' w:initrd.img ; \
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fi
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MTOOLSRC=$(obj)/mtools.conf mcopy $(obj)/bzImage w:linux ; sync
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isoimage: $(obj)/bzImage
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-rm -rf $(obj)/isoimage
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mkdir $(obj)/isoimage
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for i in lib lib64 share end ; do \
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if [ -f /usr/$$i/syslinux/isolinux.bin ] ; then \
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cp /usr/$$i/syslinux/isolinux.bin $(obj)/isoimage ; \
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break ; \
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fi ; \
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if [ $$i = end ] ; then exit 1 ; fi ; \
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done
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cp $(obj)/bzImage $(obj)/isoimage/linux
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echo '$(image_cmdline)' > $(obj)/isoimage/isolinux.cfg
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if [ -f '$(FDINITRD)' ] ; then \
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cp '$(FDINITRD)' $(obj)/isoimage/initrd.img ; \
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fi
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mkisofs -J -r -o $(obj)/image.iso -b isolinux.bin -c boot.cat \
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-no-emul-boot -boot-load-size 4 -boot-info-table \
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$(obj)/isoimage
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isohybrid $(obj)/image.iso 2>/dev/null || true
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rm -rf $(obj)/isoimage
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bzlilo: $(obj)/bzImage
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if [ -f $(INSTALL_PATH)/vmlinuz ]; then mv $(INSTALL_PATH)/vmlinuz $(INSTALL_PATH)/vmlinuz.old; fi
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if [ -f $(INSTALL_PATH)/System.map ]; then mv $(INSTALL_PATH)/System.map $(INSTALL_PATH)/System.old; fi
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cat $(obj)/bzImage > $(INSTALL_PATH)/vmlinuz
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cp System.map $(INSTALL_PATH)/
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if [ -x /sbin/lilo ]; then /sbin/lilo; else /etc/lilo/install; fi
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install:
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sh $(srctree)/$(src)/install.sh $(KERNELRELEASE) $(obj)/bzImage \
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System.map "$(INSTALL_PATH)"
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