Linux??????

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Linux??????

• ?????
• ?????????
• xlanchen_at_ustc.edu.cn
• 3606864-83(????421)
• Autumn 2007

2
???????

• Linux??
• Linux???????????
• ????????
• ??
• ???/???
• ????

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??i386?????Linux??????

• xlanchen_at_2007.9.13

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????

• ?????
• ??????
• Linux????????
• Linux?????
• Linux?????

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?????

• ??Understanding the Linux Kernel(2nd
  Edition),????Linux-2.4.18
• ????
• ????ftp//ftp.kernel.org/pub/linux/kernel/v2.6/li
  nux-2.4.18.tar.gz
• ????,??Source Insight??

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Source Insight

• ??????????
• ?http//www.sourceinsight.com/???????????,??????30
  ???

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Linux-2.6.11

• ??linux????README
• ??Linux???
• ????????????
• ??????????

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Linux????????????

• Documentation ??????????
• arch ???????????????? ???????,???????? ?i386?a
  rm?alpha??????? ???????????????
• kernel ????????????
• mm ??????????????
• lib ???????????
• include ???????????????? ????????
• init ????????

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• kernel ???????
• mm ???????
• ipc ????????
• net ???????
• lib ??????????????
• drivers ???????????????? ??,?char?block?net?
• fs ???????????????? ??????,?ext2?proc??
• modules ?????????
• Scripts ??????????

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??Arch?i386

• ?arch/i386???????

I386??????????
I386??????????
I386?????????
I386????????????
I386????????????
I386?????
I386????????Makefile
I386?Linux?????????
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I386???????

• ?arch/i386/boot???
• ?arch/i386/boot/compressed???

I386?????????????? ????????
??????????, ???????512??
I386???
?????
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• ?arch/i386/kernel????.S??
• ?init???

32?????
??????????,i386???????????, ???????main.c??start_k
ernel???
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??documentation/i386/boot.txt

• ??i386??,?????????,??Linux???????
• ??????????
• 1?Linux/i386?????(4?)
• 2??????
• 3???????????
• 4???????(command line)

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• 5???????
• 6???Linux?????
• 7?????????
• 8?????
• 9?????????
• ?????????,???????????

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????????Makefile

• ??????

??
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• ??vmlinux
• ??vmlinux????????????
• ????vmlinux??????
• i386/kernel/head.S
• init/main.c init/version.o
• CORE_FILES DRIVERS
• NETWORKS LIBS

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• ?make install
• ?i386?Makefile??install??
• ?make boot/bzImage/zImage??,?????????????
• make boot????Makefile?????boot??
• bzImage/zImage???i386?Makefile???????
• ???zXXX/bzXXX?????boot??zImage/bzImage
• ???????i386/boot?Makefile

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i386/boot?Makefile

• ?i386/boot?Makefile
• z????b?????
• ??compressed??vmlinux/bvmlinux?
• compressed/head.S ??????????vmlinux
• zImage?bootsect setup compressed/vmlinux
• bzImage?bbootsect bsetup compressed/bvmlinux

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• ?????bzImage/zImage????,??????????????????
• arch/i386/boot/bootsect.S
• arch/i386/boot/setup.S
• arch/i386/boot/compressed/head.S
• arch/i386/kernel/head.S
• ????kernel/main.C

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I386???????

• BIOS (Basic I/O System)
• Boot loader
• ?????????
• Linux kernel

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BIOS

• ??,RESET??
• ??????CSIP 0xfffffff0, in ROM
• ROM?BIOS
• BIOS????
• POST(????)
• ???????
• ???????????
• ????,?????????/??/CD_ROM?
• ??????????????(boot loader???)???RAM(0x7c00)?
• ???0x7c00???

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Boot loader(??????)

• BIOS??Boot loader??????????????RAM?
• ??IBM PC???
• ????BIOS??????????(bootsect)?RAM(0x7c00)?
• ????
• ?????????????MBR, Master Boot Record,MBR?????????
  ???????
• ??????????OS??????????(boot loader)????RAM?
• ????????????

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Linux?Boot Loader

• ????LILO?Grub
• LILO(Linux Loader)
• ??????OS????????(????)
• ?????MBR??????
• ???,LILO???????????,?????????
• MBR???????
• ????
• ??????BIOS???RAM?0x7c00???
• ?????????????????RAM?

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Linux?Boot Loader

• ??LILO?GRUB???????????????
• ???????(???????)??????????
• ?????????????????
• ???????????????

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LILO?OS????

• ??Loading
• ?????512(??????,bootsect)???????RAM?0x90000
• ??????(setup)????0x90200
• ????????????
• ?????0x10000(?64K?),?????
• ?????0x100000(?1M?),?????
• ???setup???

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I386?????

• ????
• ?????bootsect????
• ?????setup????
• ???bootsect.S????????,????????i386????????

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????I386??????????
RAM
ROM-BIOS
0xF0000
VIDEO-BIOS
0xC0000
VRAM
0xA0000
1-MB
0x00000
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I386????????????

• ???????????
• ???????????CPU????
• i386?????????
• ????
• ????20?
• ????01MB
• ???? ??? ????
• ??? ???????16 (???4?)
• ??????16bit

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??I386????????

• zImage/Image?????????????????(1M0x100000)

?????
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????,bootsect.S

• 0x7c00?0x90000
• 0x7c00, BIOS
• 0x90000, lilo
• ??,0x3ff4(0x4000-12), ????
• ?????,12Bytes,0x3ff40x4000
• ??Loading
• Setup?0x90200
• ??
• ???,0x10000(64KB?),???
• ???,0x100000(1MB?),???
• setup

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????,?????

• ??LILO(LInuxLOader)
• ?????
• ??LINUX
• Bootsect.S?0x90000
• Setup.S?0x90200
• ??
• 0x10000
• 0x100000
• ???setup

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?????,??

• ??,????setup???,??????????
• 0x90000bootsect
• 0x90200setup
• ???0x10000????vmlinux
• ???0x100000????bvmlinux
• ??????????
• ??bootsect????setup?????
• ?bootsect???0x1F1??,??????documentation/i386/boot.
  txt

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Setup0x90200

• ????????????????????
• ????
• ??
• ??
• ?????
• IBM?????MCA
• PS/2??(????)
• APM BIOS

• ????,??????0x1000?(4KB?)??,??
• ??IDT???GDT
• FPU
• PIC, 16??????????3247
• ????????
• Startup_32

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• ?compressed/head.S?head.S?????startup_32
• ??head.S?,????vmlinux???????
• ??compressed/head.S?startup_32????
• zImage?,?0x1000?
• bzImage?,?0x100000?

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Compressed/head.S

• Startup_32
• ??????????????
• ???BSS?
• ???
• ????????????0x100000(1MB)
• ???0x100000?

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• ????,vmlinux?0x100000?
• ??vmlinux.lds,vmlinux???????0xc00000000x100000?
• ????????
• ????????,????????????????
• ?????,???????????????

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Head.S

• Startup_32
• ???????
• ????0?????
• Setup_idt
• ??????
• ?????
• GDT?IDT
• Start_kernel

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??????????

• ?????,????20?,?????1MB,
• ???????????????
• ??????????,?????
• cs/ds/es/fs/gs
• 16????,????16?,???????2160x1000064KB
• ???? ????16??

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• ?????,????32?,?????4GB
• ????????????????,?GDT?????
• GDT??gdtr????????
• ???????????sgdt/lgdt

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??
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• ??setup.S?head.S??gdt/ldt
• ????gdt?idt??,?????????
• cs?ds?es?fs?gs
• cs?????????????
• ????????????

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?????(Control Registers)

• CR0
• CR1
• CR2
• CR3
• ?????

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CR0

• CR0, MSW register (Machine Status Word, 32-bit
  version)
• ???????,???????????
• Instruction lmsw
• LINUX setup.S
• movw 1, ax
• lmsw ax
• jmp flush_instr // why?
• flush_instr
• To turn on the PE-bit (enables protected-mode),

PE-bit (Protection Enabled) 0? CPU is in
real-mode, 1? CPU is in protected-mode
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CR1?CR2?CR3

• CR1??
• CR2????????,??????
• CR3?????????????????(PCD PWT)

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??2

• i386?????????20??????16???????????????
• i386??????????????????????????????????
• ??????Linux?bzImage???????