a heavily commented linux kernel source...

Linux0.11(0.95)

www.oldlinux.org

V1.9.5

[email protected]

Linux 0.11 A Heavily Commented Linux Kernel Source Code

Linux Version 0.11

1.9.5

Revision 1.9.5

Zhao Jiong

[email protected]

www.plinux.org

www.oldlinux.org

2004-05-21

Linux (v0.11)

Linux Linux LINUX Linux Linux 0.11(0.95)

Linux

.,.,,.:[email protected], : ( 1239 ,:200092).

2002,2003,2004 by Zhao Jiong 2002,2003,2004 .

RTFSC Read The F**king Source Code !

Linus Benedict Torvalds

- I -

................................................................................ 1

........................................................ 1 .................................................... 1 ........................................ 2 ........................ 2 ............................ 3 .................................... 3 ........................................ 4 EXT2 MINIX ......................... 4

1 .................................................................. 5

1.1 LINUX ........................................... 5 1.2 ........................................................... 10 1.3 ........................................................... 14

2 LINUX .................................. 15

2.1 LINUX ................................................. 15 2.2 LINUX ................................. 16 2.3 ........................................................... 18 2.4 ........................................................... 19 2.5 LINUX ................................................. 20 2.6 LINUX ......................... 26 2.7 LINUX ......................... 29 2.8 LINUX ......................... 32 2.9 ............................ 38 2.10 LINUX/MAKEFILE ...................................... 39 2.11 .......................................................... 47

3 BOOT............................. 49

3.1 ................................................................... 49 3.2 ........................................................... 49 3.3 BOOTSECT.S ................................................ 50 3.4 SETUP.S ....................................................... 58 3.5 HEAD.S ........................................................ 71 3.6 ........................................................... 80

4 (INIT)......................................... 81

4.1 ................................................................... 81 4.2 MAIN.C ........................................................ 81 4.3 ............................................... 91 4.4 ........................................................... 92

5 (KERNEL)..................................... 95

5.1 ................................................................... 95 5.2 ................................................... 95

5.3 MAKEFILE ................................................... 98 5.4 ASM.S ........................................................ 100 5.5 TRAPS.C ..................................................... 106 5.6 SYSTEM_CALL.S ........................................ 113 5.7 MKTIME.C ................................................. 123 5.8 SCHED.C .................................................... 125 5.9 SIGNAL.C ................................................... 138 5.10 EXIT.C ..................................................... 147 5.11 FORK.C .................................................... 153 5.12 SYS.C ....................................................... 160 5.13 VSPRINTF.C .............................................. 166 5.14 PRINTK.C ................................................. 174 5.15 PANIC.C ................................................... 175 5.16 ........................................................ 176

6 (BLOCK DRIVER)......... 177

6.1 ................................................................. 177 6.2 .......................................................... 177 6.3 MAKEFILE ................................................. 180 6.4 BLK.H ........................................................ 182 6.5 HD.C .......................................................... 186 6.6 LL_RW_BLK.C ........................................... 202 6.7 RAMDISK.C ................................................ 207 6.8 FLOPPY.C ................................................... 212

7 (CHAR DRIVER) ....... 239

7.1 ................................................................. 239 7.2 .................................................. 239 7.3 MAKEFILE ................................................. 247 7.4 KEYBOARD.S ............................................. 249 7.5 CONSOLE.C ................................................ 267 7.6 SERIAL.C ................................................... 290 7.7 RS_IO.S ..................................................... 293 7.8 TTY_IO.C ................................................... 297 7.9 TTY_IOCTL.C ............................................. 308

8 (MATH)................................ 317

8.1 ................................................................. 317 8.2 MAKEFILE ................................................. 317 8.3 MATH-EMULATION.C .................................. 319

9 (FS) ............................................... 321

9.1 ................................................................. 321 9.2 .................................................. 321 9.3 MAKEFILE ................................................. 327

- II -

9.4 BUFFER.C .................................................. 330 9.5 BITMAP.C ................................................... 345 9.6 INODE.C .................................................... 349 9.7 SUPER.C .................................................... 360 9.8 NAMEI.C .................................................... 369 9.9 FILE_TABLE.C ............................................ 390 9.10 BLOCK_DEV.C ......................................... 390 9.11 FILE_DEV.C .............................................. 394 9.12 PIPE.C ...................................................... 397 9.13 CHAR_DEV.C ........................................... 400 9.14 READ_WRITE.C ........................................ 403 9.15 TRUNCATE.C ............................................ 407 9.16 OPEN.C .................................................... 409 9.17 EXEC.C .................................................... 415 9.18 STAT.C ..................................................... 430 9.19 FCNTL.C .................................................. 431 9.20 IOCTL.C ................................................... 434

10 (MM).......................................... 437

10.1 ............................................................... 437 10.2 ............................................... 437 10.3 MAKEFILE ............................................... 442 10.4 MEMORY.C ............................................... 443 10.5 PAGE.S ..................................................... 457

11 (INCLUDE) ................................... 459

11.1 ............................................................... 459 11.2 INCLUDE/ ................................. 459 11.3 A.OUT.H ................................................... 460 11.4 CONST.H .................................................. 470 11.5 CTYPE.H .................................................. 471 11.6 ERRNO.H ................................................. 472 11.7 FCNTL.H .................................................. 474 11.8 SIGNAL.H ................................................. 476 11.9 STDARG.H ................................................ 478 11.10 STDDEF.H .............................................. 479 11.11 STRING.H ............................................... 480 11.12 TERMIOS.H ............................................ 490 11.13 TIME.H ................................................... 497 11.14 UNISTD.H ............................................... 498 11.15 UTIME.H ................................................ 504 11.16 INCLUDE/ASM/ ....................... 505 11.17 IO.H ....................................................... 505 11.18 MEMORY.H ............................................. 506 11.19 SEGMENT.H ........................................... 507 11.20 SYSTEM.H .............................................. 509 11.21 INCLUDE/LINUX/ .................... 512 11.22 CONFIG.H ............................................... 512 11.23 FDREG.H ............................................ 514 11.24 FS.H ....................................................... 517 11.25 HDREG.H ................................................ 523 11.26 HEAD.H ................................................. 525

11.27 KERNEL.H .............................................. 526 11.28 MM.H ..................................................... 527 11.29 SCHED.H ................................................ 527 11.30 SYS.H ..................................................... 535 11.31 TTY.H ..................................................... 537 11.32 INCLUDE/SYS/......................... 540 11.33 STAT.H ................................................... 540 11.34 TIMES.H ................................................. 541 11.35 TYPES.H ................................................. 542 11.36 UTSNAME.H ........................................... 543 11.37 WAIT.H ................................................... 544

12 (LIB)............................................... 547

12.1 ............................................................... 547 12.2 MAKEFILE ............................................... 548 12.3 _EXIT.C ................................................... 550 12.4 CLOSE.C .................................................. 550 12.5 CTYPE.C .................................................. 551 12.6 DUP.C ...................................................... 552 12.7 ERRNO.C .................................................. 553 12.8 EXECVE.C ................................................ 553 12.9 MALLOC.C ............................................... 554 12.10 OPEN.C .................................................. 562 12.11 SETSID.C ................................................ 563 12.12 STRING.C ............................................... 564 12.13 WAIT.C ................................................... 564 12.14 WRITE.C ................................................ 565

13 (TOOLS) .................................... 567

13.1 ............................................................... 567 13.2 BUILD.C ................................................... 567

14 ........................ 574

14.1 ............................................................... 574 14.2 BOCHS ............................................ 574 14.3 ........................................ 578 14.4 ........................ 581 14.5 ............................................ 584 14.6 LINUX 0.11 0.11 ........... 590 14.7 REDHAT 9 LINUX 0.11 .. 591 14.8 BOCHS ................................... 594

.................................................................... 595

............................................................................ 596

1 ............................................ 596 2 ............................................ 599 3 80X86 ................................. 607 4 ASCII ................................................. 617

............................................................................ 618

- 1 -

Linux

Linux linux linux Linux UNIX Linux

Linux Linux Redhat 7.0 2.2.16 Linux 2.2.20 268 Linux Linux Scott Maxwell Linux Linux Linux (*.h) make Linux Linux

John Lions UNIX UNIX UNIX V6 PDP-11 A.S.Tanenbaum MINIX Linux Linux Linux Linux Linux

- 2 -

Linux 1991 10 Linux Linus Toravlds Linux 0.03 LINUX--a free unix-386 kernel Linux ... GNU Hurd Linux GNU Hurd Linux Linux Linux

Linux DJJ x86Uclinux www.linux.org Linux Linux Linux Linux

Leland L. Beck (SIC) Linux Leland Linux Linux

Linux VFS a.out Linux

Linux RTFSC Read The Fucking Source Code

M.J.Bach UNIX UNIX

AST I/O

- 3 -

Linux Linux 0.11 Linux

1000

10000

100000

1000000

10000000

V0.01

V0.11

V0.12

V0.95

V0.96a

V0.97

V1.0

V1.1.52

V1.2.13

V1.3.95

V2.0.38

V2.2.20

V2.4.17

Linux 0.11 2 VFSext2 ext3

80x86 80x86 INTEL 80386 Programmer's Reference Manual 80x86 Linux Linux M.J.Bach UNIX

- 4 -

Linus Linux MINIX Linux MINIX 1.0 A.S.Tanenbaum Tanenbaum Linux

Linux Linux Tanenbaum Linux is obsolete Linux

Ext2 MINIX

Linux Ext2 Ext3 1.x Linux Linux

Linux 0.11 MINIX 1.0 Linux Linux Linux 2002.12

1.1 Linux

- 5 -

1

Linux Linux Linux

1.1 Linux

Linux UNIX 1991 10 5 Internet UNIX Linux UNIX MINIX GNU POSIX Internet Linux Linux Linus Toravlds Linux 0.01 hacker 1.0 Linux Linux 2.5.52 Linux 2.4.20 2 Linux

1.1.1 UNIX Linux UNIX UNIX Ken.Thompson Dennis Ritchie 1969 DEC PDP-7 Ken Thompson PDP-7 Space travel 1969 UNIX BCPL Dennis Ritchie 1972 C UNIX

1.1.2 MINIX MINIX Andrew S. TanenbaumASTAST Amsterdam Vrije ACM IEEE () 100 5 AST (1914 )M.I.T Berkeley Vrije Amsterdam AST MINIX 1987 1991 1.51.5 2.0

1.1 Linux

- 6 -

MINIX FTP Linux Linus Linux MINIX MINIX Linus Linux Linus MINIX C hacker

1.1.3 GNU GNU FSF(the Free Software Foundation) Richard M. Stallman 1984 UNIX GNU GNU "GNU's Not Unix""guh-NEW" Linux GNU "Linux" Stallman GNU/Linux 90 GNU emacs bash shell gcc gdb Linux Linux Linux GNU/Linux

1.1.4 POSIX POSIXPortable Operating System Interface for Computing Systems IEEE ISO/IEC UNIX 1980 UNIX (usr/group)UNIX AT&T System V Berkeley CSRG BSD 1984 /usr/group 1985 IEEE TCOS-SS ANSI IEEE 1986 4 IEEE 1988 9 IEEE 1003.1-1988POSIX.1 1989 POSIX ISO/IEC 15 ISO 1990POSIX.1 C IEEE 1003.1-1990 ANSI ISO/IEC 9945-1:1990 POSIX.1 API IEEE POSIX 300 (POSIX.2)POSIX.3 APIPOSIX.4 1990 25 16 X/OpenAT&TOSF 90 POSIX 1991-1993 Linux UNIX Linux Linux UNIX Linux 0.01 0.11 Linux POSIX Linux 0.01 /include/unistd.h POSXI Linus OK

1.1 Linux

- 7 -

1991 7 3 comp.os.minix post POSIX POSIX

1.1.5 Linux 1981 IBM IBM PC 1981-1991 MS-DOS

Apple MACs UNIX UNIX UNIX PC Bell Labs UNIX PC MINIX AST

Linux Linus Benedict Torvalds (1991 )Linus Benedict Torvalds hacker 21 GNU GNU C GNU MINIX GNU HURD Linus 386 MINIX MINIX Linus Intel 80386 Modem 80386 CPU MINIX MINIX Linus GNU GNU CGNUHURD Linus 1991 4 Intel 386 Linux Linus comp.os.minix MINIX Linux Linus 1 comp.os.minix 1991 3 29 gcc on minix-386 doesn't optimize, gcc MINIX-386 MINIX-386 Bruce Evans Intel 386 32 MINIX Linus 1991 MINIX MINIX MINIX Intel 80386 MINIX RTFSC (Read the F**ing Source Code :-)

1.1 Linux

- 8 -

1991 4 Linus MINIX-386 (Hacking the kernel) GNU (GNU gccbashgdb ) 4 13 comp.os.minix bash MINIX shell Linux 1991 7 3 comp.os.minix Linux Linus FREAX FREAX Linux POSIX Linus (1991 8 25 comp.os.minix) MINIX What would you like to see in minix?( MINIX )()386(486) GNU MINIX MINIX MINIX bash(1.08) gcc(1.40 ) Linus MINIX 386 AT Linux Linus Linux 1991 10 5 Linus comp.os.minix Linux Free minix-like kernel sources for 386-AT Linux 10 5 Linux Linux RedHat

1.1.6 Linux Linux 1.0 11

11

0.00 (1991.2-4) AAABBB

0.01 (1991.8) Linux

0.02 (1991.10.5) 0.03

0.10 (1991.10) Ted Tso Linux

0.11 (1991.12.8)

0.12 (1992.1.15)

0.95(0.13) (1992.3.8)

CDROM

0.96 (1992.5.12)

X-Windows

0.97 (1992.8.1) SCSI

0.98 (1992.9.29) TCP/IP0.8.1 extfs

0.99 (1992.12.13) 4G

1.0 (1994.3.14)

1.1 Linux

- 9 -

Linux 0.13 0.95 Linus 1.0 0.95 () Linus 2003 12 18 2.6.2 15000 gz 40MB 12

12

( gz )

2.4.22 2004.2.4 35MB

2.6.5 2004.4.4 41MB

1.1.7 Linux Linux LinuxLinus FREAX ftp.funet.fi Ari Lemke Linus Linux Linux Linus Just for FunLinus 1 Linux Freax Makefile - - Freax Ari Lemke ftp Freax (Linux)

1.1.8 Linux Linux Linux Linus Theodore Ts'o (Ted Ts'o) 1990 MIT Hacking on Linux IBM IETF Linux Linux linux Maillist Linux Linux Linux Linux 0.10 ramdisk.c kmalloc.c) Linux Linux ftp tsx-11.mit.edu Linux Linux ext2 Linux ext3 97 2002 5 Linux Journal IBM Linux

1 Linus TorvaldsJust for fun 84-88

1.2

- 10 -

Linux LSB(Linux Standard Base) Linux Alan Cox(Swansea University College) MUDMulti-User Dungeon or Dimension 90 games.mud posts MUD (rec.games.mud 1992 3 9 A history of MUD) MUD

MINIX Linux 0.11 386BSD 386SX 386BSD Intel 386SX CPU Linux Linux Linux Linux Linux (beautifully) Linux 0.95 Linux Linus Linux TCP/IP Linux Linux Linux Linus Microsoft 2001 Linux 2.4.x Linus ( 2.5.x) The Linux Kernel Hackers' Guide Michael K. Johnson Linux ( 0.97 ) Linux Linux Document Project - LDP Linux Journel RedHat Linux Linux Linux CREDITS Linux 400 email Linux UNIX -- UNIX 1969 Bell Linux UNIX UNIX MINIX -- MINIX UNIX 1987 Andrew S. Tanenbaum MINIX () UNIX Linux MINIX 1991 GNU -- Linux Linux GNU Linux GNU ( bash shell) Linux POSIX -- Linux Linux INTERNET -- Intenet Linux 0.13(0.95)

1.2

Linux 0.11 Linux-0.11 1991 12 8

1.2

- 11 -

bootimage.Z -

rootimage.Z - 1200kB

linux-0.11.tar.Z - 94KB 325KB

as86.tar.Z - Bruce Evans' 16

INSTALL-0.11 -

rootimage.Z Internet Linux 0.11 rootimage-0.11 0.11 gcc 1.40 oldlinux.org linux-0.11 Makefile shell C GNU C / Intel 8259A

Linux 0.11 Linux Linux-0.11 325K Linux 2.5.XX 188 Linux 0.01 240K 0.01

0.11 0.11 (bootimage)(rootimage) Linux 0.11 TCP/IP Linux Linux Linux

Linux 1.1 linux

1.2

- 12 -

1-1 Linux/

(GMT)

boot/ 1991-12-05 22:48:49

fs/ 1991-12-08 14:08:27

include/ 1991-09-22 19:58:04

init/ 1991-12-05 19:59:04

kernel/ 1991-12-08 14:08:00

lib/ 1991-12-08 14:10:00

mm/ 1991-12-08 14:08:21

tools/ 1991-12-04 13:11:56

Makefile 2887 bytes 1991-12-06 03:12:46

1 4 32 5 10 5 11 13 2 Linux Linux Linux/Makefile make 3 boot/ bootsect.s BIOS setup.s 32 head.s 32 4 init/ main.c shell

main.c Linux 5 kenel/ schedule()sleep_on() 6 kernel/dev_blk/

7 kernel/dev_chr/ 0.11 8 kernel/math/ 9 fs/Andrew S. Tanenbaum MINIX Linux MINIX Linux 0.11

1.2

- 13 -

10 mm/ Intel 80X86 80X86 Intel 80386 (Intel 80386 Programmer's Reference Manual) Linux 11 include/

12 Linux 0.11 lib/

0.11 13 tools/ build.c(image)kernel image 14 Bochs Linux Linux 0.11 RedHat 9 Linux PC

Linux LDPLinux Document Project HOWTO LDP Linus Linux 3 M. J. Bach UNIX UNIX System V Linus Linux John H. Crawford Programming the 8038680x86 Andrew S.Tanenbaum MINIX 1 Linus MINIX 1.0 Linux

Tanenbaum

C

Linux

1.3

- 14 -

Linux Linux GURU 1.0 Linux 2.5.44 patch

1.3

Linux UNIX Linux Rechard Stallman GNU Linux POSIX Linux A.S.T MINIX LinuxInternet Linux

2.1 Linux

- 15 -

2 Linux Linux Linux

Linux/ Makefile 4 2-1 Internet Linux X shell

2-1

Linux Linux 0.11 Linux Linux 0.11

2.1 Linux

Linux 0.11 (int x80) CPU User ModeKernel Model

2.2 Linux

- 16 -

2-2

2-2

2.2 Linux

Linux 5 CPU CPU Linux

2-3 Linux 0.11 Linux 0.95 0.96

2.2 Linux

- 17 -

2-3Linux

3

NFSramdisk Linux 0.11 2-4

2.3

- 18 -

2-4

2.3

80X86 PC 8259A 8 64 PC/AT 8259A 15 2-5 INT IR2 8259A 0x20 0xA0

2.4

- 19 -

2-5 PC/AT 8259

8259A CPU IN OUT 8259A IRQ0 IRQ15 CPU INT CPU CPU D7-D0 CPU Linux () 0-255 int0--int31(0x00--0x1f) Intel , Intel CPU (Fault)(traps) int32--int255 (0x20--0xff) Linux int32--int47(0x20--0x2f) 8259A IRQ0-IRQ15(system_call) int128(0x80)

2.4

Linux 0.11 PC Intel 8253 10 IRQ0 1 1 timer_interrupt jiffies 1 CPL do_timer() do_timer() CPL=0 stime 1 1 0 1

IR0IR1 INTIR2 IR3 8259A IR4 IR5 IR6 IR7 A0 CS CAS2-0

IRQ0 IRQ1 int IRQ2 2 IRQ3 1 IRQ4 2 IRQ5 IRQ6 1 IRQ7 0x20-0x3f

IR0 CAS2-0IR1 INTIR2 IR3 8259A IR4 IR5 IR6 IR7 A0 CS

IRQ8 INT0AH IRQ9 IRQ10 IRQ11 PS2 IRQ12 IRQ13 IRQ14 IRQ15 0xA0-0xbf

INTR CPU

D7-D0

2.5 Linux

- 20 -

0 do_timer() 0 CPU 0 do_timer() schedule() do_timer() Linux

2.5 Linux

process Linux CPU

CPU 15 =150 Linux 0.11 64 fork child processparent processprocess IDpid

CPU Linux kernel modeuser modeLinux

2.5.1 Linux task_struct include/linux/sched.h PCBProcess Control Block PDProcessor Descriptor

struct task_struct {

long state //-1 0 ()>0

long counter // ()

long priority // counter=priority

long signal // =+1

struct sigaction sigaction[32] //

long blocked //

int exit_code //

unsigned long start_code //

unsigned long end_code //

unsigned long end_data // +

unsigned long brk //

unsigned long start_stack //

2.5 Linux

- 21 -

long pid // ()

long father //

long pgrp //

long session //

long leader //

unsigned short uid // id

unsigned short euid // id

unsigned short suid // id

unsigned short gid // id

unsigned short egid // id

unsigned short sgid // id

long alarm //

long utime //

long stime //

long cutime //

long cstime //

long start_time //

unsigned short used_math //

int tty // tty -1

unsigned short umask //

struct m_inode * pwd // i

struct m_inode * root // i

struct m_inode * executable // i

unsigned long close_on_exec // include/fcntl.h

struct file * filp[NR_OPEN] // 32

struct desc_struct ldt[3] // 0-1- cs2- ds&ss

struct tss_struct tss //

};

CPU switch Linux

2.5.2 2-6 state Linux

2.5 Linux

- 22 -

2-6

TASK_RUNNING

CPU running

TASK_RUNNING TASK_INTERRUPTIBLE

TASK_UNINTERRUPTIBLE

wake_up()

TASK_STOPPED SIGSTOPSIGTSTPSIGTTIN SIGTTOU SIGCONT Linux 0.11

TASK_ZOMBIE

sleep_on() sleep_on_interruptible() CPU TASK_UNINTERRUPTIBLE TASK_INTERRUPTIBLE

running

,

running

zombie

stopped

interruptible

uninterruptible

1

2

3

40

0

0

running

2.5 Linux

- 23 -

2.5.3 boot/ init/main.c

0 0 fork() 1 1 shell 0 0 pause() 0 move_to_user_modeinclude/asm/system.h main.c 0 3 0 sched_init() 0 0 include/linux/sched.h 0 TSSLDT tr ldtr 0 0 0 0 640KB 0 16MB 0 main.c 0 0 0 main.c move_to_user_mode 0 3 0 move_to_user_mode 0 3 iret CPU 0 3 2-7

2-7

move_to_user_mode 0 0 iret iret CPU CS:EIP CPU 3 0 CPU SS:ESP DSESFS GS CPU iret

031 SS

CS

ESP

EFLAGS

EIP

SP0 - (TSS SS:ESP)

SP1 - iret SS:ESP

2.5 Linux

- 24 -

3 0 PAGE_SIZE + (long)&init_task 0 0 1 1

2.5.4 Linux fork() 0 0 64 fork()

TASK_UNINTERRUPTIBLE 15 150 TSS 0 tss.eax = 0 tss.esp0 tss.ss0 tss.ldt GDT tss.i387 1 GDT TSS LDT tss ldt

2.5.5 Linux TASK_RUNNING CPU Linux 0.11 schedule()TASK_RUNNING counter TASK_RUNNING priority counter

prioritycountercounter +=2

schdeule() TASK_RUNNING switch_to() 0Linux 0.11 0 pause() schedule()schedule() 0

2.5 Linux

- 25 -

0 switch_to()switch_to()

current TSS CPU CPU TR TSS tss tss CPU 2-8

2-8

2.5.6 exit() do_exit()

i init SIGHUP TASK_ZOMBIE SIGCHLD do_exit()

80386 CPU tss

GDT

tss

CR3

TSS

TSS

EAX

EBX

ECX

EDX

ESI

EDI

EBP

ESP

EIP

EFLAGS

CS

DS

ES

FS

GS

SS

LDTR

32 ljmp

TR

# TSS CPU

2.6 Linux

- 26 -

wait() waitpid()

2.6 Linux

Linux 0.11 2-9

2-9

Linux

RAM CPU Intel CPU Segmentation SystemPaging SystemLinux Intel CPU Linux 0.11 3 a. b. CPU c. Logical Address Intel

Linear Address

Intel 80386 4G

0 1M 640K

BIOS ROM

2.6 Linux

- 27 -

Physical Address CPU

Virtual Memory

3

Linux 0.11 64MB 0x0000000 0x4000000

CPU

,

CPU

CPU 80386 CPU CR2

Swapper Linux 0.11 mm/memory.c Intel CPU Segment

Linux 0.11 CPU GDT LDT LDT LDT 2-10

2.6 Linux

- 28 -

2-10 Linux

idtLinux 0.11 Linux 0.11 4096 Intel 80386 CPU 4G Linux 0.11 GDT 256 2 2 (256-4)/2 + 1=127 ((256-4)/2)* 64MB 8G 0.11 NR_TASKS = 64 64M(-1)*64MB 64MB*64 =4G 2-11 4G CPU 0.11

0 64M

()0 2 1

128M 192M 4G

- - -

ldtN

tssN

0

Data

Code

0

0

1

Data

Code

1

1

ldt1

tss1

ldt0

tss0

sys

Data

Code

NULL

GDT LDT

LDT

2.7 Linux

- 29 -

2-11 Linux 0.11

CPU PDT PT 64MB*64M 10 Linux 0.99 4G

2.7 Linux

Linux Linux 0.11 0

2.7.1 (bootsect.ssetup.s) bootsect ROM BIOS 0x7c00 bootsect 0x9000:0 SS 0x9000esp 0xff00 0x9000:0xff00 boot/bootsect.s 6162 setup.s bootsect (head.s) head.s 0x10 esp user_stack head.s 31 1 4Kuser_stack sched.c 67--72 1024 2-12

2.7 Linux

- 30 -

2-12

(main.c) main.c move_to_user_mode()move_to_user_mode()main.c 0 fork()main.c init() 1 1 main() 0 0 0

2.7.2 4096 3K 64MB 0 64MB 64MB CPU Linux Copy on Write task_structfork() tss (tss.esp0 tss.ss0)kernel/fork.c93 p->tss.esp0 = PAGE_SIZE + (long)p;

p->tss.ss0 = 0x10;

p tss task_struct tss task_struct tss.ss0

kernel

0x0000

ss

esp

system

kernel

user_stack[1k],1

*task[]

main

gdt(2k)

idt(2k)

(4k X 4)

(4k)

head

sched

2.7 Linux

- 31 -

0x10 tss.esp0 task_struct 2-13

2-13

tss.ss0 0x10 head.s 16MB Linux 0.11 head.s110 Linux 0.98 1GB CPU TSS (esp0) CPU 0 0 0 0 640KB move_to_user_mode() sched.c user_stack 0 movie_to_user_mode() iret esp user_stack ss 0x17 0 640KB 2-7

2.7.3

eflags iret eflags 2-14

(current)

(esp0)

1 (4096 )

2.8 Linux

- 32 -

2-14

2.8 Linux

Linux

Linux

tar linux-0.11.tar.gz linux/ 2-15

2-15 Linux

14 102

2.8.1 linux linux 14 Makefile make make

SS

ESP

EFLAGS

CS

EIP

IRET

INT

linux

boot

fs

include (*.h)

asm CPU

linux Linux

sys

init

kernel

blk_drv

chr_drv

math

lib

mm

tools Image

2.8 Linux

- 33 -

make linux Makefile Makefile linuxmake linux make

2.8.2 boot boot 3 3 32 bootsect.s setup.s as86 as86 head.s GNU as AT&T bootsect.s 0 0 1 PC ROM BIOS BIOS 0x7C00 setup.s system head.s system

2.8.3 fs Linux 0.11 1.0 MINIX Linux MINIX MINIX MINIX Linux MINIX Linux MINIX MINIX Linux Linux Linux MINIX Linux sleep() fs/ 17 C 2-16 .c

2.8 Linux

- 34 -

2-16 fs

buffer.c file_table.c ioctl.c

kernel/chr_drv/tty.c io exec.c do_execve() exec()fcntl.c i/o read_write.c /stat.c open.c

char_dev.c rw_char()pipe.c file_dev.c i namei.c block_dev.c inode.c i truncate.c bitmap.c i super.c buffer.c ll_rw_block fs kernel/blk_drv/ll_rw_block.c

ll_rw_block()

read_write

block dev char dev

bitmap

buffer

file devpipe

inode

super

exec

truncate

namei

open

ll_rw_block

ioctlfile_table

stat

fcntl

2.8 Linux

- 35 -

2.8.4 include 32 .h 13 asm 4 linux 10 sys 5 a.out a.out i i_mode (Linus minix ) -va_listva_start, va_arg va_end vsprintfvprintfvfprintf NULL, offsetof(TYPE, MEMBER) tm Linux __LIBRARY___syscall0() utime() include/asm CPU 4 io io memcpy() / Linux include/linux HD_TYPE file,buffer_head,m_inode head task_struct 0 72 C ,'sys_' tty tty_io include/sys stat{} tms times() wait() waitpid()

2.8 Linux

- 36 -

2.8.5 init main.c shell task 0 fork() init() shell

2.8.6 kernel linux/kernel 12 Makefile 3 kernel/ forkexit get_hd_block tty_write

2-17

2-17

asm.s traps.c traps.c C exit.c fork.c sys_fork() C find_empty_process()copy_process() mktime.c mktime() 1970 1 1 0 init/main.c panic. panic() printk.c printk() sched.c (sleep_onwakeupschedule ) signal.c4 do_signal() sys.c system_call.s Linux int 0x80 C Linux

mktime

schedule.c

panic.c

pintk,vsprintf

asm.s

traps.c

system_call.s

fork.c,sys.c,exit.c,signal.c

2.8 Linux

- 37 -

vsprintf.c kernel/blk_drv

blk_drv 4 c 1 blk.h C 2-18

2-18 blk_drv

blk.h 3 C hd.c / do_hd__request()floppy.c / do_fd_request() ll_rw_blk.c /ll_rw_block() fs/buffer.c kernel/chr_drv 4 C 2 rs-232 2-19

2-19

tty_io.c tty tty_read() tty_write() C do_tty_interrupt()

console.c con_write() tty con_init() rs_io.s 0x3fa 0x2fa 4 do_tty_interrupt() serial.c UART

ll_rw_blk.c

hd.c floppy.c

blk.h

ramdisk.c

tty_io.c

serial.c rs_io.s

tty_ioctl.c

console.c keyboard.S

2.9

- 38 -

tty rs_write() tty_ioctl.c tty io tty_ioctl() termio(s) io sys_ioctl() fs/ioctl.c keyboard.S keyboard_interrupt kernel/math C math_emulate.c math_emulate() int7 C CPU

SIGFPE

2.8.7 lib init/main.c 01 libc lib/ 12 C tytso malloc.c _exit() close(fd) dup() open() write() execve() malloc() wait() setsid() include/string.h

2.8.8 mm 2

Linux 386 4G 64 64MB fork page.s int 14 memory.c mem_init() page.s do_no_page() do_wp_page()

2.8.9 tools build.c Linux image

2.9

Linux 5 int 0x80 12 C libc C

2.10 linux/Makefile

- 39 -

libc ID include/linux/unistd.h Linux LSBLinux Standard Base Linux 2 C / I/O fopen fclose open close

3

2.10 linux/Makefile

linux Makefile

2.10.1 Makefile make

Makefile make Makefile make make Makefile

Makefile make make Makefile (last-modification time) Makefile Makefile '#''=' Makefile make tools/ build image boot/bootsect.ssetup.s 8086 GNU gcc/gas system build image. / 2-20

2.10 linux/Makefile

- 40 -

2-20 /

2.10.2 2-1 linux/Makefile

1 #

2 # if you want the ram-disk device, define this to be the # RAM

3 # size in blocks. #

4 #

5 RAMDISK = #-DRAMDISK=512

6

7 AS86 =as86 -0 -a # 8086

8 LD86 =ld86 -0 # -0 8086 -a gas gld

9

10 AS =gas # GNU

11 LD =gld

12 LDFLAGS =-s -x -M # GNU gld -s

# -x -M

# ()(link map)

#

#

#

#

#

13 CC =gcc $(RAMDISK) # gcc GNU C UNIX (script)

# $

14 CFLAGS =-Wall -O -fstrength-reduce -fomit-frame-pointer \

15 -fcombine-regs -mstring-insns # gcc '\'

# -Wall -O

# -fstrength-reduce -mstring-insns

# Linus gcc gcc gcc-1.40

# 386 CPU

16 CPP =cpp -nostdinc -Iinclude # cpp gcc ()-nostdinc -Iinclude

# -I

#

head main kernel mm fs lib

bootsect setup system

Build

Image

2.10 linux/Makefile

- 41 -

17

18 #

19 # ROOT_DEV specifies the default root-device when making the image.

20 # This can be either FLOPPY, /dev/xxxx or empty, in which case the

21 # default of /dev/hd6 is used by 'build'.

22 #

23 ROOT_DEV=/dev/hd6 # ROOT_DEV (image)

# (FLOPPY)/dev/xxxx

# build tools//dev/hd6

24

25 ARCHIVES=kernel/kernel.o mm/mm.o fs/fs.o # kernel mm fs

#

# ARCHIVES

26 DRIVERS =kernel/blk_drv/blk_drv.a kernel/chr_drv/chr_drv.a # .a

#

# GNU ar ar GNU

#

27 MATH =kernel/math/math.a #

28 LIBS =lib/lib.a # lib/

29

30 .c.s: # make make

# .c .s ':'

31 $(CC) $(CFLAGS) \

32 -nostdinc -Iinclude -S -o $*.s $< # gcc CFLAGS

# include/

# -S C

# C .c

# .s -o $*.s$@

# $ Image

43 sync # tools build

# bootsectsetup system

# $(ROOT_DEV) Image

# sync

44

45 disk: Image # disk Image

46 dd bs=8192 if=Image of=/dev/PS0 # dd UNIX

# bs=/

# if=of=

2.10 linux/Makefile

- 42 -

# /dev/PS0 ()

47

48 tools/build: tools/build.c # tools build.c build

49 $(CC) $(CFLAGS) \

50 -o tools/build tools/build.c # build

51

52 boot/head.o: boot/head.s # .s.o head.o

53

54 tools/system: boot/head.o init/main.o \

55 $(ARCHIVES) $(DRIVERS) $(MATH) $(LIBS) # tools system

#

56 $(LD) $(LDFLAGS) boot/head.o init/main.o \

57 $(ARCHIVES) \

58 $(DRIVERS) \

59 $(MATH) \

60 $(LIBS) \

61 -o tools/system > System.map # system > System.map

# gld System.map

# System.map

62

63 kernel/math/math.a: # math.a

64 (cd kernel/math; make) # kernel/math/ make

# 66--82

65

66 kernel/blk_drv/blk_drv.a: # blk_drv.a

67 (cd kernel/blk_drv; make)

68

69 kernel/chr_drv/chr_drv.a: # chr_drv.a

70 (cd kernel/chr_drv; make)

71

72 kernel/kernel.o: # kernel.o

73 (cd kernel; make)

74

75 mm/mm.o: # mm.o

76 (cd mm; make)

77

78 fs/fs.o: # fs.o

79 (cd fs; make)

80

81 lib/lib.a: # lib.a

82 (cd lib; make)

83

84 boot/setup: boot/setup.s # 8086

85 $(AS86) -o boot/setup.o boot/setup.s # setup.s setup

86 $(LD86) -s -o boot/setup boot/setup.o # -s

87

88 boot/bootsect: boot/bootsect.s # bootsect.o

89 $(AS86) -o boot/bootsect.o boot/bootsect.s

90 $(LD86) -s -o boot/bootsect boot/bootsect.o

91

92 tmp.s: boot/bootsect.s tools/system # 92--95 bootsect.s

# system SYSSIZE = system

# tmp.s bootsect.s system

2.10 linux/Makefile

- 43 -

# ls system grep

# tmp.s cut tr

# ( + 15)/16 1 = 16

93 (echo -n "SYSSIZE = (";ls -l tools/system | grep system \

94 | cut -c25-31 | tr '\012' ' '; echo "+ 15 ) / 16") > tmp.s

95 cat boot/bootsect.s >> tmp.s

96 a

97 clean: # 'make clean' 98--103

# 'rm'-f

98 rm -f Image System.map tmp_make core boot/bootsect boot/setup

99 rm -f init/*.o tools/system tools/build boot/*.o

100 (cd mm;make clean) # mm/ Makefile clean

101 (cd fs;make clean)

102 (cd kernel;make clean)

103 (cd lib;make clean)

104 a

105 backup: clean # clean linux/

# backup.Z 'cd .. ' linux/

# 'tar cf - linux' linux/ tar -cf

# '| compress -' tar ('|')

# compress backup.Z

106 (cd .. ; tar cf - linux | compress - > backup.Z)

107 sync #

108

109 dep:

# make

# make

# *.c

# sed Makefile Makefile

# '### Dependencies' 118 tmp_make

# 110 init/ C

# main.c gcc -M

# make make

# --

# 111 $$i $($i)$i shell

# tmp_make Makefile

110 sed '/\#\#\# Dependencies/q' < Makefile > tmp_make

111 (for i in init/*.c;do echo -n "init/";$(CPP) -M $$i;done) >> tmp_make

112 cp tmp_make Makefile

113 (cd fs; make dep) # fs/ Makefile

114 (cd kernel; make dep)

115 (cd mm; make dep)

116

117 ### Dependencies:

118 init/main.o : init/main.c include/unistd.h include/sys/stat.h \

119 include/sys/types.h include/sys/times.h include/sys/utsname.h \

120 include/utime.h include/time.h include/linux/tty.h include/termios.h \

121 include/linux/sched.h include/linux/head.h include/linux/fs.h \

122 include/linux/mm.h include/signal.h include/asm/system.h include/asm/io.h \

123 include/stddef.h include/stdarg.h include/fcntl.h

2.10 linux/Makefile

- 44 -

2.10.3 Makefile makefile make Make makefile makefile GNU make make makefile make makefile make makefile make

make makefile makefile make make C C (object file) makefile

(target)... : (prerequisites)... (command) ... ... ''''('clean')'''' make make

$^$

2.10 linux/Makefile

- 45 -

$

2.10 linux/Makefile

- 46 -

-m

-n

-o

-s

-u

-w

ld

Minix a.out

ld [-03Mims[-]] [-T textaddr] [-llib_extension] [-o outfile] infile...

GNU-Minix a.out

ld [-03Mimrs[-]] [-T textaddr] [-llib_extension] [-o outfile] infile...

():

-03 32

outfile a.out

-0 16 -lx i86

-3 32 -lx i386

-M

-T ( strtoul )

-i I&D

-lx /local/lib/subdir/libx.a

-m

-o

-r

-s

System.map System.map System.map System.map System.map c03441a0 B dmi_broken

c03441a4 B is_sony_vaio_laptop

c03441c0 b dmi_ident

c0344200 b pci_bios_present

c0344204 b pirq_table

dmi_broken c03441a0

System.map ( klogd) klogd System.map klogd System.map /boot/System.map

/System.map

/usr/src/linux/System.map

2.11

- 47 -

System.map klogdlsofps dosemu System.map

2.11

Linux Linux 0.11 RedHat 9 Linux 0.11 Linux makefile

3.1

- 49 -

3 boot

3.1

boot/ 3-1 bootsect.s setup.s Intel Intel 8086 as86 ld86 head.s GNU GNU as AT&T Intel x86 GNU i386 CPU

3-1 linux/boot/

() (GMT)

bootsect.s 5052 bytes 1991-12-05 22:47:58

head.s 5938 bytes 1991-11-18 15:05:09

setup.s 5364 bytes 1991-12-05 22:48:10

8086 Intel 80X86 PC 80386 32 PC 80386 32

3.2

Linux PC 80x86 CPU 0xFFFF0 ROM-BIOS PC BIOS 0 512 0x7C00 Linux 8086 (boot/bootsect.s) BIOS 0x7C00(31KB) 0x90000(576KB) 2kB(boot/setup.s) 0x90200 system 0x10000 system 0x80000 512KB 0x90000 bootsect setup setup system system 3-1 Linux

3.3 bootsect.s

- 50 -

"Loading..." boot/setup.s

3-1

vga 0x10000 0x0000 0x0000 32 : IDTGDT LDT init/main.c main() boot/head.S

0x0000 setup setup ROM BIOS BIOS 0x400 (1Kb) BIOS

3.3 bootsect.s

3.3.1 bootsect.s 0 0 1 PC ROM BIOS BIOS 0x7C00 0x90000 setup setup.s bootsect 0x90200, BIOS 0x13

1 2 3 4 5 6

0x7c00

0x0000

0x90000

0x10000

0xA0000

bootsect.s

setup.s

system

system head.s

0x90200

3.3 bootsect.s

- 51 -

Loading system... system 0x10000

1.44M A root_dev( 0x508 ) setup 0x90200 setup

3.3.2 3-1 linux/boot/bootsect.s

1 !

2 ! SYS_SIZE is the number of clicks (16 bytes) to be loaded.

3 ! 0x3000 is 0x30000 bytes = 196kB, more than enough for current

4 ! versions of linux

! SYS_SIZE 16 1 0x3000

! 0x30000 =196 kB 1024 1KB 192KB

5 !

6 SYSSIZE = 0x3000 ! system 2.1 92

!

7 !

8 ! bootsect.s (C) 1991 Linus Torvalds

9 !

10 ! bootsect.s is loaded at 0x7c00 by the bios-startup routines, and moves

11 ! iself out of the way to address 0x90000, and jumps there.

12 !

13 ! It then loads 'setup' directly after itself (0x90200), and the system

14 ! at 0x10000, using BIOS interrupts.

15 !

16 ! NOTE! currently system is at most 8*65536 bytes long. This should be no

17 ! problem, even in the future. I want to keep it simple. This 512 kB

18 ! kernel size should be enough, especially as this doesn't contain the

19 ! buffer cache as in minix

20 !

21 ! The loader has been made as simple as possible, and continuos

22 ! read errors will result in a unbreakable loop. Reboot by hand. It

23 ! loads pretty fast by getting whole sectors at a time whenever possible.

!

!

! bootsect.s (C) 1991 Linus Torvalds

!

! bootsect.s bios- 0x7c00 (31k)

! 0x90000 (576k)

!

! BIOS 'setup'(0x90200)(576.5k)

! system 0x10000

!

! ! (8*65536)(512k)

! 512k

! minix

!

!

!

24

3.3 bootsect.s

- 52 -

25 .globl begtext, begdata, begbss, endtext, enddata, endbss ! 6

26 .text !

27 begtext:

28 .data !

29 begdata:

30 .bss ! (Block Started by Symbol)

31 begbss:

32 .text !

33

34 SETUPLEN = 4 ! nr of setup-sectors

! setup (setup-sectors)

35 BOOTSEG = 0x07c0 ! original address of boot-sector

! bootsect

36 INITSEG = 0x9000 ! we move boot here - out of the way

! bootsect --

37 SETUPSEG = 0x9020 ! setup starts here

! setup

38 SYSSEG = 0x1000 ! system loaded at 0x10000 (65536).

! system 0x1000064 kB

39 ENDSEG = SYSSEG + SYSSIZE ! where to stop loading

!

40

41 ! ROOT_DEV: 0x000 - same type of floppy as boot.

!

42 ! 0x301 - first partition on first drive etc

!

43 ROOT_DEV = 0x306 ! 2 1 Linux

! ,

! =*256 + dev_no = (major

3.3 bootsect.s

- 53 -

56 jmpi go,INITSEG ! INITSEG

! CPU 0x9000

57 go: mov ax,cs ! dses ss (0x9000)

58 mov ds,ax (push,pop,call)

59 mov es,ax

60 ! put stack at 0x9ff00. ! sp 0x9ff00( 0x9000:0xff00)

61 mov ss,ax

62 mov sp,#0xFF00 ! arbitrary value >>512

!

! sp 512 0x90200

! 0x90200 setup

! setup 4 sp

! 0x200 + 0x200 * 4 +

63

64 ! load the setup-sectors directly after the bootblock.

65 ! Note that 'es' is already set up.

! bootsect setup

! es es 0x9000

66

67 load_setup:

! 68--77 BIOS INT 0x13 setup 2

! 0x90200 4

! INT 0x13

!

! ah = 0x02 - al =

! ch = () 8 cl = (0-5 ) 2 (6-7)

! dh = dl = 7

! es:bx CF

68 mov dx,#0x0000 ! drive 0, head 0

69 mov cx,#0x0002 ! sector 2, track 0

70 mov bx,#0x0200 ! address = 512, in INITSEG

71 mov ax,#0x0200+SETUPLEN ! service 2, nr of sectors

72 int 0x13 ! read it

73 jnc ok_load_setup ! ok - continue

74 mov dx,#0x0000

75 mov ax,#0x0000 ! reset the diskette

76 int 0x13

77 j load_setup

78

79 ok_load_setup:

80

81 ! Get disk drive parameters, specifically nr of sectors/track

!

! INT 0x13

! ah = 0x08 dl = 7 1

!

! CF ah =

! ah = 0 al = 0 bl = AT/PS2

! ch = 8 cl = ( 0-5) 2 ( 6-7)

! dh = dl =

! es:di -

82

83 mov dl,#0x00

3.3 bootsect.s

- 54 -

84 mov ax,#0x0800 ! AH=8 is get drive parameters

85 int 0x13

86 mov ch,#0x00

87 seg cs ! cs

88 mov sectors,cx !

89 mov ax,#INITSEG

90 mov es,ax ! es

91

92 ! Print some inane message ! ('Loading system ...' 24 )

93

94 mov ah,#0x03 ! read cursor pos

95 xor bh,bh !

96 int 0x10

97

98 mov cx,#24 ! 24

99 mov bx,#0x0007 ! page 0, attribute 7 (normal)

100 mov bp,#msg1 !

101 mov ax,#0x1301 ! write string, move cursor

102 int 0x10 !

103

104 ! ok, we've written the message, now

105 ! we want to load the system (at 0x10000) ! system 0x10000(64k)

106

107 mov ax,#SYSSEG

108 mov es,ax ! segment of 0x010000 ! es = system

109 call read_it ! system es

110 call kill_motor !

111

112 ! After that we check which root-device to use. If the device is

113 ! defined (!= 0), nothing is done and the given device is used.

114 ! Otherwise, either /dev/PS0 (2,28) or /dev/at0 (2,8), depending

115 ! on the number of sectors that the BIOS reports currently.

! (!=0)

! BIOS

! /dev/PS0 (2,28) /dev/at0 (2,8)

!

! Linux 2( 43 ) = type*4 + nr

! nr 0-3 ABC Dtype 2 1.2M 7 1.44M

! 7*4 + 0 = 28 /dev/PS0 (2,28) 1.44M A , 0x021c

! /dev/at0 (2,8) 1.2M A 0x0208

116

117 seg cs

118 mov ax,root_dev !

119 cmp ax,#0

120 jne root_defined

121 seg cs

122 mov bx,sectors ! 88 sectors=15

! 1.2Mb sectors=18

! 1.44Mb A

123 mov ax,#0x0208 ! /dev/ps0 - 1.2Mb

124 cmp bx,#15 ! =15

125 je root_defined ! ax

126 mov ax,#0x021c ! /dev/PS0 - 1.44Mb

3.3 bootsect.s

- 55 -

127 cmp bx,#18

128 je root_defined

129 undef_root: !

130 jmp undef_root

131 root_defined:

132 seg cs

133 mov root_dev,ax !

134

135 ! after that (everyting loaded), we jump to

136 ! the setup-routine loaded directly after

137 ! the bootblock:

!

! bootsect setup

138

139 jmpi 0,SETUPSEG ! 0x9020:0000(setup.s )

!!!! !!!!

!

140

141 ! This routine loads the system at address 0x10000, making sure

142 ! no 64kB boundaries are crossed. We try to load it as fast as

143 ! possible, loading whole tracks whenever we can.

144 !

145 ! in: es - starting address segment (normally 0x1000)

146 !

! 0x10000 64KB

!

! es 0x1000

147 sread: .word 1+SETUPLEN ! sectors read of current track

! 1

! bootsect setup SETUPLEN

148 head: .word 0 ! current head !

149 track: .word 0 ! current track !

150

151 read_it:

! 64KB

! bx

152 mov ax,es

153 test ax,#0x0fff

154 die: jne die ! es must be at 64kB boundary ! es 64KB !

155 xor bx,bx ! bx is starting address within segment ! bx

156 rp_read:

! (#ENDSEG)

! ok1_read

157 mov ax,es

158 cmp ax,#ENDSEG ! have we loaded all yet? !

159 jb ok1_read

160 ret

161 ok1_read:

! ax

!

! 64KB (64KB

3.3 bootsect.s

- 56 -

! )

162 seg cs

163 mov ax,sectors !

164 sub ax,sread !

165 mov cx,ax ! cx = ax =

166 shl cx,#9 ! cx = cx * 512

167 add cx,bx ! cx = cx + (bx)

! =

168 jnc ok2_read ! 64KB ok2_read

169 je ok2_read

170 xor ax,ax ! 64KB

171 sub ax,bx ! (64KB )

172 shr ax,#9 !

173 ok2_read:

174 call read_track

175 mov cx,ax ! cx =

176 add ax,sread !

177 seg cs

178 cmp ax,sectors ! ok3_read

179 jne ok3_read

! (1 )

180 mov ax,#1

181 sub ax,head !

182 jne ok4_read ! 0 1

183 inc track !

184 ok4_read:

185 mov head,ax !

186 xor ax,ax !

187 ok3_read:

188 mov sread,ax !

189 shl cx,#9 ! *512

190 add bx,cx !

191 jnc rp_read ! 64KB rp_read(156 )

!

192 mov ax,es

193 add ax,#0x1000 ! 64KB

194 mov es,ax

195 xor bx,bx !

196 jmp rp_read ! rp_read(156 )

197

! es:bx 67 BIOS

! int 0x13ah=2

! al es:bx

198 read_track:

199 push ax

200 push bx

201 push cx

202 push dx

203 mov dx,track !

204 mov cx,sread !

205 inc cx ! cl =

206 mov ch,dl ! ch =

207 mov dx,head !

3.3 bootsect.s

- 57 -

208 mov dh,dl ! dh =

209 mov dl,#0 ! dl = ( 0 A )

210 and dx,#0x0100 ! 1

211 mov ah,#2 ! ah = 2

212 int 0x13

213 jc bad_rt ! bad_rt

214 pop dx

215 pop cx

216 pop bx

217 pop ax

218 ret

! 0 read_track

219 bad_rt: mov ax,#0

220 mov dx,#0

221 int 0x13

222 pop dx

223 pop cx

224 pop bx

225 pop ax

226 jmp read_track

227

228 /*

229 * This procedure turns off the floppy drive motor, so

230 * that we enter the kernel in a known state, and

231 * don't have to worry about it later.

232 */

!

233 kill_motor:

234 push dx

235 mov dx,#0x3f2 !

236 mov al,#0 ! A FDC DMA

237 outb ! al dx

238 pop dx

239 ret

240

241 sectors:

242 .word 0 !

243

244 msg1:

245 .byte 13,10 ! ASCII

246 .ascii "Loading system ..."

247 .byte 13,10,13,10 ! 24 ASCII

248

249 .org 508 ! 508(0x1FC) root_dev

! 508 2

250 root_dev:

251 .word ROOT_DEV ! (init/main.c

)

252 boot_flag:

253 .word 0xAA55 !

254

255 .text

256 endtext:

3.4 setup.s

- 58 -

257 .data

258 enddata:

259 .bss

260 endbss:

3.3.3 bootsect.s Alessandro RubiniLinux (http://oldlinux.org/Linux.old/docs/) 386 80x86 [1][16] Linux 0.11

3.4 setup.s

3.4.1 setup ROM BIOS 0x90000 bootsect 31 ttyio.c

31 setup

()

0x90000 2 0x00-0x00-

0x90002 2 1M KB

0x90004 2

0x90006 1

0x90007 1

0x90008 2 ??

0x9000A 1 (0x00-64k,0x01-128k,0x02-192k,0x03=256k)

0x9000B 1 0x00-,I/O=0x3dX0x11-,I/O=0x3bX

0x9000C 2

...

0x90080 16 1

0x90090 16 2

0x901FC 2 bootsec.s

setup system 0x10000-0x8ffff system 512KB 0x00000 (idtr)(gdtr) A20 8259A0x20 - 0x2f CPU CR0 32 system head.s head.s 32 idt

3.4 setup.s

- 59 -

gdt gdt head.s CPU 32 ds 64KB si 3-2 (a)

16 3-2 (b)

3-2

gdt lgdt CPUgdt gdtr 32

3.4.2 3-2 linux/boot/setup.s

1 !

2 ! setup.s (C) 1991 Linus Torvalds

3 !

4 ! setup.s is responsible for getting the system data from the BIOS,

5 ! and putting them into the appropriate places in system memory.

6 ! both setup.s and system has been loaded by the bootblock.

7 !

ds

si

ds

esi

gdtr

64kb

(a) (b)

3.4 setup.s

- 60 -

8 ! This code asks the bios for memory/disk/other parameters, and

9 ! puts them in a "safe" place: 0x90000-0x901FF, ie where the

10 ! boot-block used to be. It is then up to the protected mode

11 ! system to read them from there before the area is overwritten

12 ! for buffer-blocks.

!

! setup.s BIOS

! setup.s system bootsect

!

! bios //

! 0x90000-0x901FF bootsect

! system

13 !

14

15 ! NOTE! These had better be the same as in bootsect.s!

! bootsect.s

16

17 INITSEG = 0x9000 ! we move boot here - out of the way ! bootsect

18 SYSSEG = 0x1000 ! system loaded at 0x10000 (65536). ! system 0x10000(64k)

19 SETUPSEG = 0x9020 ! this is the current segment !

20

21 .globl begtext, begdata, begbss, endtext, enddata, endbss

22 .text

23 begtext:

24 .data

25 begdata:

26 .bss

27 begbss:

28 .text

29

30 entry start

31 start:

32

33 ! ok, the read went well so we get current cursor position and save it for

34 ! posterity.

! ok

35

36 mov ax,#INITSEG ! this is done in bootsect already, but...

! ds #INITSEG(0x9000) bootsect

! setup Linus

!

37 mov ds,ax

38 mov ah,#0x03 ! read cursor pos

! BIOS 0x10 ah = 0x03

! bh =

! ch = cl =

! dh = (0x00 )dl = (0x00 )

39 xor bh,bh

40 int 0x10 ! save it in known place, con_init fetches

41 mov [0],dx ! it from 0x90000.

! 0x90000

!

42

3.4 setup.s

- 61 -

43 ! Get memory size (extended mem, kB) ! 3 KB

! 0x15 ah = 0x88

! ax = 0x1000001M(KB)

! CF ax =

44

45 mov ah,#0x88

46 int 0x15

47 mov [2],ax ! 0x90002 1

48

49 ! Get video-card data: !

! BIOS 0x10 ah = 0x0f

! ah = al = bh =

! 0x90004(1 )0x90006 0x90007

50

51 mov ah,#0x0f

52 int 0x10

53 mov [4],bx ! bh = display page

54 mov [6],ax ! al = video mode, ah = window width

55

56 ! check for EGA/VGA and some config parameters ! EGA/VGA

! BIOS 0x10 -

! ah = 0x12bl = 0x10

! bh =

! (0x00 - I/O =0x3dX)

! (0x01 - I/O =0x3bX)

! bl =

! (0x00 - 64k, 0x01 - 128k, 0x02 - 192k, 0x03 = 256k)

! cx = ()

57

58 mov ah,#0x12

59 mov bl,#0x10

60 int 0x10

61 mov [8],ax ! 0x90008 = ??

62 mov [10],bx ! 0x9000A = 0x9000B = (/)

63 mov [12],cx ! 0x9000C =

64

65 ! Get hd0 data !

! 1 0x41 2

! 1 0x46 2

! 16 (0x10)

! BIOS 0x90080 1

! 0x90090 2

66

67 mov ax,#0x0000

68 mov ds,ax

69 lds si,[4*0x41] ! 0x41 hd0 ds:si

70 mov ax,#INITSEG

71 mov es,ax

72 mov di,#0x0080 ! : 0x9000:0x0080 es:di

73 mov cx,#0x10 ! 0x10

74 rep

75 movsb

76

3.4 setup.s

- 62 -

77 ! Get hd1 data

78

79 mov ax,#0x0000

80 mov ds,ax

81 lds si,[4*0x46] ! 0x46 hd1 ds:si

82 mov ax,#INITSEG

83 mov es,ax

84 mov di,#0x0090 ! : 0x9000:0x0090 es:di

85 mov cx,#0x10

86 rep

87 movsb

88

89 ! Check that there IS a hd1 :-) ! 2 2

! BIOS 0x13

! ah = 0x15

! dl = 0x8X 0x80 1 0x81 2

! ah = 00 --CF 01 -- change-line

! 02 --() change-line 03 --

90

91 mov ax,#0x01500

92 mov dl,#0x81

93 int 0x13

94 jc no_disk1

95 cmp ah,#3 ! ( = 3 )

96 je is_disk1

97 no_disk1:

98 mov ax,#INITSEG ! 2 2

99 mov es,ax

100 mov di,#0x0090

101 mov cx,#0x10

102 mov ax,#0x00

103 rep

104 stosb

105 is_disk1:

106

107 ! now we want to move to protected mode ... ! ...

108

109 cli ! no interrupts allowed ! !

110

111 ! first we move the system to it's rightful place

! system

! bootsect system 0x1000064k

! system 0x80000512k 0x90000

! bootsect 0x90000 setup

! system 0x00000 0x10000 0x8ffff

! (512k) 0x1000064k

112

113 mov ax,#0x0000

114 cld ! 'direction'=0, movs moves forward

115 do_move:

116 mov es,ax ! destination segment ! es:di ( 0x0000:0x0)

117 add ax,#0x1000

118 cmp ax,#0x9000 ! 0x8000 64k

3.4 setup.s

- 63 -

119 jz end_move

120 mov ds,ax ! source segment ! ds:si ( 0x1000:0x0)

121 sub di,di

122 sub si,si

123 mov cx,#0x8000 ! 0x8000 64k

124 rep

125 movsw

126 jmp do_move

127

128 ! then we load the segment descriptors

!

! 32 Intel 32 ,

!

!

!

!

! lidt (idt) 6 0-1

! ()2-5 32

! 219-220 223-224 8

!

!

! lgdt (gdt) lidt

! (8 )

! (16 )32

! 205-216

!

129

130 end_move:

131 mov ax,#SETUPSEG ! right, forgot this at first. didn't work :-)

132 mov ds,ax ! ds (setup)

133 lidt idt_48 ! load idt with 0,0

! (idt)idt_48 6

! ( 218 ) 2 idt 4 idt

!

134 lgdt gdt_48 ! load gdt with whatever appropriate

! (gdt)gdt_48 6

! ( 222 )

135

136 ! that was painless, now we enable A20

! A20 A20

! kernel/chr_drv/keyboard.S

137

138 call empty_8042 !

!

139 mov al,#0xD1 ! command write ! 0xD1 -

140 out #0x64,al ! 8042 P2 P2 1 A20

! 0x60

141 call empty_8042 !

142 mov al,#0xDF ! A20 on ! A20

143 out #0x60,al

144 call empty_8042 ! A20

145

146 ! well, that went ok, I hope. Now we have to reprogram the interrupts :-(

3.4 setup.s

- 64 -

147 ! we put them right after the intel-reserved hardware interrupts, at

148 ! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really

149 ! messed this up with the original PC, and they haven't been able to

150 ! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,

151 ! which is used for the internal hardware interrupts as well. We just

152 ! have to reprogram the 8259's, and it isn't fun.

!!

!! intel int 0x20-0x2F

!! IBM PC

!! PC bios 0x08-0x0f

!! 8259

153

154 mov al,#0x11 ! initialization sequence

! 0x11 ICW1

! 8259 ICW4

155 out #0x20,al ! send it to 8259A-1 ! 8259A

!

! 0xeb 1 -127 127CPU

! EIP EIP

! CPU 7 10 0x00eb 0

! 14-20 CPU as86

! Linus setup.s

! NOP 3 6 7 NOP

156 .word 0x00eb,0x00eb ! jmp $+2, jmp $+2 ! '$'

157 out #0xA0,al ! and to 8259A-2 ! 8259A

158 .word 0x00eb,0x00eb

159 mov al,#0x20 ! start of hardware int's (0x20)

160 out #0x21,al ! ICW2


162 mov al,#0x28 ! start of hardware int's 2 (0x28)

163 out #0xA1,al ! ICW2


165 mov al,#0x04 ! 8259-1 is master

166 out #0x21,al ! ICW3 IR2 INT


168 mov al,#0x02 ! 8259-2 is slave

169 out #0xA1,al ! ICW3 INT

! IR2


171 mov al,#0x01 ! 8086 mode for both

172 out #0x21,al ! ICW4 8086 EOI

!


174 out #0xA1,al ICW4


176 mov al,#0xFF ! mask off all interrupts for now

177 out #0x21,al !


179 out #0xA1,al

180

181 ! well, that certainly wasn't fun :-(. Hopefully it works, and we don't

182 ! need no steenking BIOS anyway (except for the initial loading :-).

183 ! The BIOS-routine wants lots of unnecessary data, and it's less

3.4 setup.s

- 65 -

184 ! "interesting" anyway. This is how REAL programmers do it.

185 !

186 ! Well, now's the time to actually move into protected mode. To make

187 ! things as simple as possible, we do no register set-up or anything,

188 ! we let the gnu-compiled 32-bit programs do that. We just jump to

189 ! absolute address 0x00000, in 32-bit protected mode.

!! BIOS

!! BIOS !!

190

! 32 (lmsw-Load Machine Status Word)

! CR0 0 1 CPU

191 mov ax,#0x0001 ! protected mode (PE) bit ! (PE)

192 lmsw ax ! This is it! ! !

193 jmpi 0,8 ! jmp offset 0 of segment 8 (cs) ! cs 8 0

! system 0x00000 0

! 8

! 16 2 0-1 0-3linux

! 0 3 2 (0)

! (1) 3-15

! 8(0b0000,0000,0000,1000) 0 1

! 0 209 system

194

195 ! This routine checks that the keyboard command queue is empty

196 ! No timeout is used - if this hangs there is something wrong with

197 ! the machine, and we probably couldn't proceed anyway.

! -

! PC

! 2 = 0

198 empty_8042:

199 .word 0x00eb,0x00eb ! ()

200 in al,#0x64 ! 8042 status port ! AT

201 test al,#2 ! is input buffer full? ! 2

202 jnz empty_8042 ! yes - loop

203 ret

204

205 gdt: ! 8

! 3 1 206 2

! 208-211 3 (213-216 )

!

206 .word 0,0,0,0 ! dummy ! 1

207 ! gdt 0x08()

208 .word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb)

209 .word 0x0000 ! base address=0

210 .word 0x9A00 ! code read/exec

211 .word 0x00C0 ! granularity=4096, 386

212 ! gdt 0x10( ds )

213 .word 0x07FF ! 8Mb - limit=2047 (2048*4096=8Mb)

214 .word 0x0000 ! base address=0

215 .word 0x9200 ! data read/write

216 .word 0x00C0 ! granularity=4096, 386

217

218 idt_48:

3.4 setup.s

- 66 -

219 .word 0 ! idt limit=0

220 .word 0,0 ! idt base=0L

221

222 gdt_48:

223 .word 0x800 ! gdt limit=2048, 256 GDT entries

! 2k 8

! 256

224 .word 512+gdt,0x9 ! gdt base = 0X9xxxx

! 4 0x0009

3.4 setup.s

- 67 -

NULL 0x0000 setup.s 'jmp 0,8 ' 193 head.s '8' gdt '0' 3.4.3.2 BIOS 0x10 ROM BIOS A.

32 ah = 0x12bh = 0x10

/

ah =0x12

bh =0x10

bh

0x00 I/O 0x3DX

0x01 I/O 0x3BX

X 0 f

bl

00 = 64K, 01 = 128K, 02 = 192K, 03 = 256K

ch

0 1 2

1 0 2

2 1 1

3 0 1

4-7 ( 0)

cl

0 1

1 2

2 3

3 4

4-7

EGA/VGA :

0x00 MDA/HGC

0x01-0x03 MDA/HGC

0x04 CGA 40x25

0x05 CGA 80x25

0x06 EGA+ 40x25

0x07-0x09 EGA+ 80x25

0x0A EGA+ 80x25

0x0B EGA+ 80x25

3.4 setup.s

- 68 -

3.4.3.3 INT 0x41 int 0x41 4 * 0x41 =0x0000:0x0104 100% BIOS F000h:E401h int 0x46

33

0x00 cyl

0x02 head

0x03 ( PC XT 0)

0x05 wpcom 4

0x07 ECC XT 0

0x08 ctl

0

1 (0) ( IRQ)

2

3 8 1

4 (0)

5 +1 1

6 ECC

7

0x09 XT 0

0x0A XT 0

0x0B XT 0

0x0C lzone ()

0x0E sect

0x0F

3.4.3.4 A20 1981 8 IBM IBM PC CPU Intel 8088 20 (A0 A19) RAM KB 1MB 20 0xffff:0xffff 0x10ffef 0x100000(1MB) 0x0ffef IBM 1985 AT Intel 80286 CPU 24 16MB 8088 1MB 8088 IBM 0x100000 8042 P2 P21 A20 20 A20

A20 setup.s 138-144 A20

3.4 setup.s

- 69 -

A20 A20 A20 (Fast Gate A20) I/O 0x92 A20 0x92 0xee A20 A20 3.4.3.5 8259 8259A 8 64 PC/AT 8259A 15 3-4 INT IR2 8259A 0x20 0xA0

3-4 PC/AT 8259

CPU IN OUT 8259A IRQ0 IRQ15 CPU INT CPU CPU D7-D0 CPU Linux int 320x20int 0 - int 31 CPU int32 -- int 47 3.4.3.6 Intel CPU 32 Intel CPU Intel CPU8088/8086 Intel 80386 32 4G

IR0IR1 INTIR2 IR3 8259A IR4 IR5 IR6 IR7 A0 CS CAS2-0

IRQ0 IRQ1 int IRQ2 2 IRQ3 1 IRQ4 2 IRQ5 IRQ6 1 IRQ7 0x20-0x3f

IR0 CAS2-0IR1 INTIR2 IR3 8259A IR4 IR5 IR6 IR7 A0 CS

IRQ8 INT0AH IRQ9 IRQ10 IRQ11 PS2 IRQ12 IRQ13 IRQ14 IRQ15 0xA0-0xbf

INTR CPU

D7-D0

3.4 setup.s

- 70 -

Linux

setup.s head.s 80x86 3.4.3.7 Intel 80386 CPU 4 GDTR Global Descriptor Table Register LDTR Local Descriptor Table Register GDT LDT IDTR Interrupt Descriptor Table Register IDT TR Task Register task{} 3.4.3.8 Intel 80386 4 CR0CR1CR2CR3 MOV 3-5 31 23 15 7 0

Page Directory Base Register (PDBR)

Reserved CR3

Page Fault Linear Address CR2

Reserved CR1

P

G

Reserved

E

T

T

S

E

M

M

P

P

ECR0

3-5

CR0

PE Protection Enable 0 MP Math Present 1 WAIT EM Emulation 2 TS Task Switch 3 ET Extention Type 4 80287 80387 PG Paging 31 10

CR2 PG CPU CR3 PG CPU

3.5 head.s

- 71 -

3.5 head.s

3.5.1 head.s system(head)heads.s AT&T GNU gas gld2 0 idt 256 gdt 0 1M A20 1Mb CPU IP MOD 1Mb PC 8028780387 CR0 0 16MB 4 /init/main.c main()

3.5.2 3-3 linux/boot/head.s

1 /*

2 * linux/boot/head.s

3 *

4 * (C) 1991 Linus Torvalds

5 */

6

7 /*

8 * head.s contains the 32-bit startup code.

9 *

10 * NOTE!!! Startup happens at absolute address 0x00000000, which is also where

11 * the page directory will exist. The startup code will be overwritten by

12 * the page directory.

13 */

/*

* head.s 32

* !!! 32 0x00000000

*

*/

14 .text

15 .globl _idt,_gdt,_pg_dir,_tmp_floppy_area

16 _pg_dir: #

17 startup_32: # 18-22

18 movl $0x10,%eax # GNU '$'

2 Linux gas gld as ld

3.5 head.s

- 72 -

# '%'eax 32 ax

# !!! 32 $0x10 0x10

#

# setup.s 193 $0x10

# 0( 0-1=0)( 2=0) 2 ( 3-15=2)

# setup.s 212213

# ds,es,fs,gs setup.s

# 2 =0x10 stack_start user_stack

# setup.s

# 8MB 16MBstack_start kernel/sched.c69

# user_stack

19 mov %ax,%ds

20 mov %ax,%es

21 mov %ax,%fs

22 mov %ax,%gs

23 lss _stack_start,%esp # _stack_start ss:esp

# stack_start kernel/sched.c69

24 call setup_idt #

25 call setup_gdt #

26 movl $0x10,%eax # reload all the segment registers

27 mov %ax,%ds # after changing gdt. CS was already

28 mov %ax,%es # reloaded in 'setup_gdt'

29 mov %ax,%fs # gdt

30 mov %ax,%gs # CS setup_gdt

# setup.s 8MB 16MB setup.s 208-216

# 235-236

# bochs CS 26 CS

# 8MB CS CS

31 lss _stack_start,%esp

# 32-36 A20 0x000000

# 0x100000(1M)

# A20 1M

32 xorl %eax,%eax

33 1: incl %eax # check that A20 really IS enabled

34 movl %eax,0x000000 # loop forever if it isn't

35 cmpl %eax,0x100000

36 je 1b # '1b'(backward) 1 33

# '5f'(forward) 5

37 /*

38 * NOTE! 486 should set bit 16, to check for write-protect in supervisor

39 * mode. Then it would be unnecessary with the "verify_area()"-calls.

40 * 486 users probably want to set the NE (#5) bit also, so as to use

41 * int 16 for math errors.

42 */

/*

* ! 486 16 ,

* "verify_area()"486 NE(#5)

* int 16

*/

# 43-65 CR0

#

# CR0 EM 2 MP 1

3.5 head.s

- 73 -

43 movl %cr0,%eax # check math chip

44 andl $0x80000011,%eax # Save PG,PE,ET

45 /* "orl $0x10020,%eax" here for 486 might be good */

46 orl $2,%eax # set MP

47 movl %eax,%cr0

48 call check_x87

49 jmp after_page_tables # 135

50

51 /*

52 * We depend on ET to be correct. This checks for 287/387.

53 */

/*

* ET 287/387

*/

54 check_x87:

55 fninit

56 fstsw %ax

57 cmpb $0,%al

58 je 1f /* no coprocessor: have to set bits */

59 movl %cr0,%eax # 1 cr0

60 xorl $6,%eax /* reset MP, set EM */

61 movl %eax,%cr0

62 ret

63 .align 2 # ".align 2""2" 2

# 4

64 1: .byte 0xDB,0xE4 /* fsetpm for 287, ignored by 387 */ # 287

65 ret

66

67 /*

68 * setup_idt

69 *

70 * sets up a idt with 256 entries pointing to

71 * ignore_int, interrupt gates. It then loads

72 * idt. Everything that wants to install itself

73 * in the idt-table may do so themselves. Interrupts

74 * are enabled elsewhere, when we can be relatively

75 * sure everything is ok. This routine will be over-

76 * written by the page tables.

77 */

/*

* setup_idt

*

* idt 256 ignore_int

* ( lidt )

*

*/

# 8

# (Gate Descriptor) 0-1,6-7 2-3 4-5

78 setup_idt:

79 lea ignore_int,%edx # ignore_int edx

80 movl $0x00080000,%eax # 0x0008 eax 16

81 movw %dx,%ax /* selector = 0x0008 = cs */

# 16 eax 16 eax

3.5 head.s

- 74 -

# 4

82 movw $0x8E00,%dx /* interrupt gate - dpl=0, present */

83 # edx 4

84 lea _idt,%edi # _idt

85 mov $256,%ecx

86 rp_sidt:

87 movl %eax,(%edi) #

88 movl %edx,4(%edi)

89 addl $8,%edi # edi

90 dec %ecx

91 jne rp_sidt

92 lidt idt_descr #

93 ret

94

95 /*

96 * setup_gdt

97 *

98 * This routines sets up a new gdt and loads it.

99 * Only two entries are currently built, the same

100 * ones that were built in init.s. The routine

101 * is VERY complicated at two whole lines, so this

102 * rather long comment is certainly needed :-).

103 * This routine will beoverwritten by the page tables.

104 */

/*

* setup_gdt

* gdt

* *

*/

105 setup_gdt:

106 lgdt gdt_descr # ( 234-238 )

107 ret

108

109 /*

110 * I put the kernel page tables right after the page directory,

111 * using 4 of them to span 16 Mb of physical memory. People with

112 * more than 16MB will have to expand this.

113 */

/* Linus 4 16 Mb

* 16 Mb

*/

# 4 Kb 1 4

# 1024 4 Kb 4 Mb

# 0-11 (P 0)(R/W 1)

# (U/S 2)()(D 6) 12-31

#

114 .org 0x1000 # 0x1000 1 0

115 pg0:

116

117 .org 0x2000

118 pg1:

119

3.5 head.s

- 75 -

120 .org 0x3000

121 pg2:

122

123 .org 0x4000

124 pg3:

125

126 .org 0x5000 # 0x5000

127 /*

128 * tmp_floppy_area is used by the floppy-driver when DMA cannot

129 * reach to a buffer-block. It needs to be aligned, so that it isn't

130 * on a 64kB border.

131 */

/* DMA tmp_floppy_area

* 64kB

*/

132 _tmp_floppy_area:

133 .fill 1024,1,0 # 1024 1 0

134

# (pushl)/init/main.c

# 3 0 envpargv argc main()

# 139 main.c

# main.c L6

# 140 main.c setup_paging

# 'ret' main.c main.c

135 after_page_tables:

136 pushl $0 # These are the parameters to main :-)

137 pushl $0 # main init/main.c

138 pushl $0 # '$'

139 pushl $L6 # return address for main, if it decides to.

140 pushl $_main # '_main' main

141 jmp setup_paging # 198

142 L6:

143 jmp L6 # main should never return here, but

144 # just in case, we know what happens.

145

146 /* This is the default interrupt "handler" :-) */

/* */ 147 int_msg:

148 .asciz "Unknown interrupt\n\r" # ()

149 .align 2 # 4

150 ignore_int:

151 pushl %eax

152 pushl %ecx

153 pushl %edx

154 push %ds # ds,es,fs,gs 16

# 32 4

155 push %es

156 push %fs

157 movl $0x10,%eax # ds,es,fs gdt

158 mov %ax,%ds

159 mov %ax,%es

160 mov %ax,%fs

161 pushl $int_msg # printk

3.5 head.s

- 76 -

162 call _printk # /kernel/printk.c

# '_printk' printk

163 popl %eax

164 pop %fs

165 pop %es

166 pop %ds

167 popl %edx

168 popl %ecx

169 popl %eax

170 iret # CPU 32

171

172

173 /*

174 * Setup_paging

175 *

176 * This routine sets up paging by setting the page bit

177 * in cr0. The page tables are set up, identity-mapping

178 * the first 16MB. The pager assumes that no illegal

179 * addresses are produced (ie >4Mb on a 4Mb machine).

180 *

181 * NOTE! Although all physical memory should be identi

a heavily commented linux kernel source...

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