wok-6.x annotate linux/stuff/linux-header-2.6.33.2.u @ rev 5259

linux/boot: fix noinitramfs case
author Pascal Bellard <pascal.bellard@slitaz.org>
date Tue Apr 13 12:30:20 2010 +0200 (2010-04-13)
parents 2ae67cafd57e
children 9ce35fbe98df
rev   line source
pankso@5245 1 --- linux-2.6.30.6/arch/x86/boot/header.S
pankso@5245 2 +++ linux-2.6.30.6/arch/x86/boot/header.S
pankso@5245 3 @@ -6,7 +6,7 @@
pankso@5245 4 * Based on bootsect.S and setup.S
pankso@5245 5 * modified by more people than can be counted
pankso@5245 6 *
pankso@5245 7 - * Rewritten as a common file by H. Peter Anvin (Apr 2007)
pankso@5245 8 + * Rewritten Pascal Bellard (Nov 2009)
pankso@5245 9 *
pankso@5245 10 * BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
pankso@5245 11 * addresses must be multiplied by 16 to obtain their respective linear
pankso@5245 12 @@ -26,6 +26,8 @@
pankso@5245 13
pankso@5245 14 BOOTSEG = 0x07C0 /* original address of boot-sector */
pankso@5245 15 SYSSEG = 0x1000 /* historical load address >> 4 */
pankso@5245 16 +INITSEG = 0x9000 /* boot address >> 4 */
pankso@5245 17 +SETUPSEG = 0x9020 /* setup address >> 4 */
pankso@5245 18
pankso@5245 19 #ifndef SVGA_MODE
pankso@5245 20 #define SVGA_MODE ASK_VGA
pankso@5245 21 @@ -39,53 +41,412 @@
pankso@5245 22 #define ROOT_RDONLY 1
pankso@5245 23 #endif
pankso@5245 24
pankso@5245 25 +/* some extra features */
pankso@5245 26 +#define EDIT_CMDLINE on hotkey
pankso@5245 27 +#define SHOW_REGS show int13 status & parameters
pankso@5245 28 +
pankso@5245 29 .code16
pankso@5245 30 .section ".bstext", "ax"
pankso@5245 31
pankso@5245 32 .global bootsect_start
pankso@5245 33 bootsect_start:
pankso@5245 34 + cld # assume nothing
pankso@5245 35 +stacktop = 0x9E00 # in 0x8000 .. 0xA000
pankso@5245 36 +zeroed = 48+10 # gdt + zeroed registers
pankso@5245 37 + movw $stacktop-12-zeroed, %di # stacktop is an arbitrary value >=
pankso@5245 38 + # length of bootsect + length of
pankso@5245 39 + # setup + room for stack;
pankso@5245 40 + # 12 is disk parm size.
pankso@5245 41 + pushw $INITSEG
pankso@5245 42 + popw %es # %es = INITSEG
pankso@5245 43
pankso@5245 44 - # Normalize the start address
pankso@5245 45 - ljmp $BOOTSEG, $start2
pankso@5245 46 + pushw %es
pankso@5245 47 + popw %ss # %ss and %es already contain INITSEG
pankso@5245 48 + movw %di, %sp # put stack at INITSEG:stacktop-...
pankso@5245 49
pankso@5245 50 -start2:
pankso@5245 51 - movw %cs, %ax
pankso@5245 52 - movw %ax, %ds
pankso@5245 53 - movw %ax, %es
pankso@5245 54 - movw %ax, %ss
pankso@5245 55 - xorw %sp, %sp
pankso@5245 56 - sti
pankso@5245 57 - cld
pankso@5245 58 +# Many BIOS's default disk parameter tables will not recognize
pankso@5245 59 +# multi-sector reads beyond the maximum sector number specified
pankso@5245 60 +# in the default diskette parameter tables - this may mean 7
pankso@5245 61 +# sectors in some cases.
pankso@5245 62 +#
pankso@5245 63 +# Since single sector reads are slow and out of the question,
pankso@5245 64 +# we must take care of this by creating new parameter tables
pankso@5245 65 +# (for the first disk) in RAM. We can set the maximum sector
pankso@5245 66 +# count to 36 - the most we will encounter on an ED 2.88.
pankso@5245 67 +#
pankso@5245 68 +# High doesn't hurt. Low does. Let's use the max: 63
pankso@5245 69 +#
pankso@5245 70 +# Segments are as follows: %es = %ss = INITSEG,
pankso@5245 71
pankso@5245 72 - movw $bugger_off_msg, %si
pankso@5245 73 + xorw %ax, %ax # %ax = 0
pankso@5245 74 + movw $zeroed/2, %cx # clear gdt + offset, %ds, limits
pankso@5245 75 + rep # don't worry about cld
pankso@5245 76 + stosw # already done above
pankso@5245 77 + popw %bx # offset = 0
pankso@5245 78 + popw %ds # %ds = 0
pankso@5245 79 + popw %gs # %gs = 0
pankso@5245 80
pankso@5245 81 -msg_loop:
pankso@5245 82 - lodsb
pankso@5245 83 - andb %al, %al
pankso@5245 84 - jz bs_die
pankso@5245 85 - movb $0xe, %ah
pankso@5245 86 - movw $7, %bx
pankso@5245 87 + movb setup_sects+0x7C00, %al # read bootsector + setup (%ds = 0)
pankso@5245 88 + incw %ax
pankso@5245 89 +
pankso@5245 90 + pushw %es
pankso@5245 91 + pushw %di # %ds:%bx+0x78 is parameter table address
pankso@5245 92 + ldsw 0x78(%bx), %si # %ds:%si is source
pankso@5245 93 + movb $6, %cl # copy 12 bytes
pankso@5245 94 + rep # don't worry about cld
pankso@5245 95 + movsw # already done above
pankso@5245 96 + popl %gs:0x78(%bx) # update parameter table address
pankso@5245 97 + pushw %es
pankso@5245 98 + popw %ds # now %ds = %es = %ss = INITSEG
pankso@5245 99 + movb $63, 0x4-12(%di) # patch sector count, %di = stacktop
pankso@5245 100 + cli
pankso@5245 101 +
pankso@5245 102 + xchg %ax, %di # sector count
pankso@5245 103 + popw %ax # limits = 0
pankso@5245 104 + incw %cx # cylinder 0, sector 1
pankso@5245 105 + call read_first_sectors # read setup
pankso@5245 106 +
pankso@5245 107 +offset_version = 0xE
pankso@5245 108 + movw $0x200,%si
pankso@5245 109 + addw offset_version(%si),%si # starting protocol 2.00, Kernel 1.3.73
pankso@5245 110 + call puts # show which kernel we are loading
pankso@5245 111 +
pankso@5245 112 +# The cmdline can be entered and modifed at boot time.
pankso@5245 113 +# Only characters before the cursor are passed to the kernel.
pankso@5245 114 + popw %bx # clear %bx
pankso@5245 115 + orw cmd_line_ptr, %bx
pankso@5245 116 + jz nocmdline
pankso@5245 117 + pushw %bx
pankso@5245 118 + call read_one_sector
pankso@5245 119 + popw %si
pankso@5245 120 + call puts
pankso@5245 121 +#ifdef EDIT_CMDLINE
pankso@5245 122 +cmdlp:
pankso@5245 123 + movb $0x20, %al # clear end of line
pankso@5245 124 + int $0x10 # with Space
pankso@5245 125 + movb $8, %al # and BackSpace
pankso@5245 126 int $0x10
pankso@5245 127 - jmp msg_loop
pankso@5245 128 + decw %si
pankso@5245 129 +cmdget:
pankso@5245 130 + call wait4key
pankso@5245 131 + cmpb $8, %al # BackSpace ?
pankso@5245 132 + je cmdbs
pankso@5245 133 + movb %al, (%si) # store char
pankso@5245 134 + lodsw # %si += 2
pankso@5245 135 +cmdbs:
pankso@5245 136 +#if 1
pankso@5245 137 + cmpw %si,cmd_line_ptr
pankso@5245 138 + je cmdget
pankso@5245 139 +#endif
pankso@5245 140 + call putc # set %ah and %bx
pankso@5245 141 + cmpb $10, %al # Enter ?
pankso@5245 142 + jne cmdlp
pankso@5245 143 + movb %bh,-2(%si) # set end of string and remove CR
pankso@5245 144 +endcmdline:
pankso@5245 145 +#endif
pankso@5245 146 +nocmdline:
pankso@5245 147
pankso@5245 148 -bs_die:
pankso@5245 149 - # Allow the user to press a key, then reboot
pankso@5245 150 - xorw %ax, %ax
pankso@5245 151 - int $0x16
pankso@5245 152 - int $0x19
pankso@5245 153 +# This routine loads the system at address SYSSEG, making sure
pankso@5245 154 +# no 64kB boundaries are crossed. We try to load it as fast as
pankso@5245 155 +# possible, loading whole tracks whenever we can.
pankso@5245 156
pankso@5245 157 - # int 0x19 should never return. In case it does anyway,
pankso@5245 158 - # invoke the BIOS reset code...
pankso@5245 159 - ljmp $0xf000,$0xfff0
pankso@5245 160 +ramdisk_image = 0x0218
pankso@5245 161 +ramdisk_size = 0x021C
pankso@5245 162 + movw %sp, %si # for bootsect_gdt
pankso@5245 163 + decw 16(%si) # bootsect_src = 64Kb
pankso@5245 164 + decw 24(%si) # bootsect_dst = 64Kb
pankso@5245 165 + movw $syssize, %di
pankso@5245 166 +type_of_loader = 0x210
pankso@5245 167 +loadflags = 0x211
pankso@5245 168 +heap_end_ptr = 0x224
pankso@5245 169 +ksyssize = 500
pankso@5245 170 + orw $0x80FF, type_of_loader-ksyssize(%di) # loader type = 0xFF
pankso@5245 171 + movw $stacktop-0x200, heap_end_ptr-ksyssize(%di)
pascal@5259 172 + movb $0x10, %al # destination = 0x100000
pankso@5245 173 + movb $5, %cl
pankso@5245 174 +initrdlp:
pascal@5259 175 + decw %ax
pankso@5245 176 + movb $0x93,%ah
pankso@5245 177 + movw %ax, 28(%si) # bootsect_dst_base+2
pankso@5245 178 + movb $(SYSSEG/4096), %al # source = SYSSEG
pankso@5245 179 + movw %ax, 20(%si) # bootsect_src_base+2
pankso@5245 180 + cbw
pankso@5245 181 + cwde
pankso@5245 182 + shlw %cl, %ax
pankso@5245 183 + decw %ax
pankso@5245 184 + addl (%di),%eax
pankso@5245 185 + shrl %cl, %eax
pankso@5245 186 +syslp:
pankso@5245 187 + pushw $SYSSEG
pankso@5245 188 + popw %es
pankso@5245 189 + movw $128,%di # 64Kb
pankso@5245 190 + subw %di, %ax # max 32M > int 15 limit
pankso@5245 191 + pushf
pankso@5245 192 + jnc not_last
pankso@5245 193 + addw %ax, %di
pankso@5245 194 +not_last:
pankso@5245 195 + xorw %bx, %bx # clear %bx
pankso@5245 196 + pushw %ax
pankso@5245 197 +#if defined(SHOW_REGS)
pankso@5245 198 + pushw %si
pankso@5245 199 + call read_sectors
pankso@5245 200 + popw %si
pankso@5245 201 +#else
pankso@5245 202 + call read_sectors
pankso@5245 203 +#endif
pankso@5245 204 + movw $0x8000, %cx # full 64K
pankso@5245 205 + movb $0x87, %ah
pankso@5245 206 + incb 28(%si) # bootsect_dst_base+2
pankso@5245 207 + int $0x15 # max 16M
pankso@5245 208 + popw %ax
pankso@5245 209 + popf
pankso@5245 210 + ja syslp
pankso@5245 211 + movw ramdisk_image+2,%ax
pankso@5245 212 + movw $ramdisk_size,%di
pankso@5245 213 + movb $9, %cl
pankso@5245 214 + cmpb %al,28(%si)
pankso@5245 215 + jb initrdlp
pankso@5245 216
pankso@5245 217 - .section ".bsdata", "a"
pankso@5245 218 -bugger_off_msg:
pankso@5245 219 - .ascii "Direct booting from floppy is no longer supported.\r\n"
pankso@5245 220 - .ascii "Please use a boot loader program instead.\r\n"
pankso@5245 221 - .ascii "\n"
pankso@5245 222 - .ascii "Remove disk and press any key to reboot . . .\r\n"
pankso@5245 223 - .byte 0
pankso@5245 224 +# This procedure turns off the floppy drive motor, so
pankso@5245 225 +# that we enter the kernel in a known state, and
pankso@5245 226 +# don't have to worry about it later.
pankso@5245 227
pankso@5245 228 +#if 1
pankso@5245 229 +kill_motor:
pankso@5245 230 + xchgw %ax, %bx # reset FDC
pankso@5245 231 + int $0x13
pankso@5245 232 +#else
pankso@5245 233 +kill_motor:
pankso@5245 234 + movw $0x3f2, %dx
pankso@5245 235 + xchgw %ax, %bx
pankso@5245 236 + outb %al, %dx
pankso@5245 237 +#endif
pankso@5245 238 +
pankso@5245 239 +# After that (everything loaded), we jump to the setup-routine
pankso@5245 240 +# loaded directly after the bootblock:
pankso@5245 241 +# Segments are as follows: %ds = %ss = INITSEG
pankso@5245 242 +
pankso@5245 243 + ljmp $SETUPSEG, $0
pankso@5245 244 +
pankso@5245 245 +# read_sectors reads %di sectors into %es:0 buffer.
pankso@5245 246 +# %es:0 is updated to the next memory location.
pankso@5245 247 +# First, sectors are read sector by sector until
pankso@5245 248 +# sector per track count is known. Then they are
pankso@5245 249 +# read track by track.
pankso@5245 250 +# Assume no error on first track.
pankso@5245 251 +
pankso@5245 252 +#define FLOPPY_CYLINDERS 80 /* 80 cylinders minimum */
pankso@5245 253 +#define FLOPPY_HEADS 2 /* 2 heads minimum */
pankso@5245 254 +#define FLOPPY_SECTORS 18 /* 18 sectors minimum */
pankso@5245 255 +
pankso@5245 256 +#ifdef SHOW_REGS
pankso@5245 257 +print_loop:
pankso@5245 258 + movb $0x6 + 'A' - 1, %al
pankso@5245 259 + subb %cl, %al
pankso@5245 260 + movw $regs, %si # caller %si is saved
pankso@5245 261 + call putcs # putc(%al) + puts(%si)
pankso@5245 262 +# it will print out all of the registers.
pankso@5245 263 + popw %bp # load word into %si
pankso@5245 264 + jmp print_all # print %bp (status)
pankso@5245 265 +#endif
pankso@5245 266 +check_limits:
pankso@5245 267 +#ifndef SHOW_REGS
pankso@5245 268 + popw %dx
pankso@5245 269 +#endif
pankso@5245 270 + cmpb $FLOPPY_SECTORS+1, %cl # 18 sectors minimum
pankso@5245 271 + jb check_head
pankso@5245 272 + cmpb %al, %cl # max sector known ?
pankso@5245 273 + ja next_head # no -> store it
pankso@5245 274 +check_head:
pankso@5245 275 + cmpb $FLOPPY_HEADS, %dh # 2 heads minimum
pankso@5245 276 + jb check_cylinder
pankso@5245 277 + cmpb %ah, %dh # max head known ?
pankso@5245 278 + ja next_cylinder # no -> store it
pankso@5245 279 +check_cylinder:
pankso@5245 280 + pushaw
pankso@5245 281 +#ifdef SHOW_REGS
pankso@5245 282 + cmpw $0x600,%bp # disk changed ?
pankso@5245 283 + je reset_floppy
pankso@5245 284 + pushw %es # print %es (named EX)
pankso@5245 285 + pushw %dx # print %dx
pankso@5245 286 + pushw %cx # print %cx
pankso@5245 287 + pushw %bx # print %bx
pankso@5245 288 + xchgw %ax, %si
pankso@5245 289 + movb $2,%ah
pankso@5245 290 + pushw %ax # print %ax
pankso@5245 291 + movb $6,%cl
pankso@5245 292 +print_all:
pankso@5245 293 + movb $4, %ch # 4 hex digits
pankso@5245 294 +print_digit:
pankso@5245 295 + rolw $4, %bp # rotate to use low 4 bits
pankso@5245 296 + movb $0x0f, %al
pankso@5245 297 + andw %bp, %ax # %al = mask for nybble
pankso@5245 298 + addb $0x90, %al # convert %al to ascii hex
pankso@5245 299 + daa # in only four instructions!
pankso@5245 300 + adcb $0x40, %al
pankso@5245 301 + daa
pankso@5245 302 + call putc # set %ah and %bx
pankso@5245 303 + decb %ch
pankso@5245 304 + jnz print_digit
pankso@5245 305 + movb $0x20, %al # SPACE
pankso@5245 306 + int $0x10
pankso@5245 307 + loop print_loop
pankso@5245 308 + call wait
pankso@5245 309 + cbw # %ah = 0
pankso@5245 310 +reset_floppy:
pankso@5245 311 +#else
pankso@5245 312 + cbw # %ah = 0
pankso@5245 313 +#endif
pankso@5245 314 + int $0x13 # reset controler
pankso@5245 315 + popaw
pankso@5245 316 +read_sectorslp:
pankso@5245 317 + pushw %dx # some bios break dx...
pankso@5245 318 + pushw %ax # limits
pankso@5245 319 + subb %cl, %al # sectors remaining in track
pankso@5245 320 + ja tolastsect
pankso@5245 321 + movb $1, %al # 1 sector mini
pankso@5245 322 +tolastsect:
pankso@5245 323 + cbw
pankso@5245 324 + cmpw %di, %ax
pankso@5245 325 + jb more1trk
pankso@5245 326 + movw %di, %ax # sectors to read
pankso@5245 327 +more1trk:
pankso@5245 328 + pushw %ax # save context
pankso@5245 329 + movb $2, %ah # cmd: read chs
pankso@5245 330 + int $0x13
pankso@5245 331 +#ifdef SHOW_REGS
pankso@5245 332 + xchgw %ax, %bp # status
pankso@5245 333 +#endif
pankso@5245 334 +# ifdef SHOW_REGS
pankso@5245 335 + popw %si # save %ax
pankso@5245 336 + popw %ax # limits
pankso@5245 337 + popw %dx
pankso@5245 338 +# else
pankso@5245 339 + popw %dx # save %ax
pankso@5245 340 + popw %ax # limits
pankso@5245 341 +# endif
pankso@5245 342 + jc check_limits
pankso@5245 343 +# ifdef SHOW_REGS
pankso@5245 344 +update_regs:
pankso@5245 345 + decw %di # update sector counter
pankso@5245 346 + incw %cx # next sector
pankso@5245 347 + addb $2,%bh # next location
pankso@5245 348 + decw %si
pankso@5245 349 + jnz update_regs
pankso@5245 350 +# else
pankso@5245 351 + subw %dx,%di # update sector counter
pankso@5245 352 + addw %dx,%cx # next sector
pankso@5245 353 + addw %dx,%dx
pankso@5245 354 + addb %dl,%bh # next location
pankso@5245 355 + popw %dx
pankso@5245 356 +# endif
pankso@5245 357 + cmpb %al,%cl # reach sector limit ?
pankso@5245 358 + jne bdendlp
pankso@5245 359 +next_head:
pankso@5245 360 + movb %cl,%al
pankso@5245 361 + incb %dh # next head
pankso@5245 362 + movb $1,%cl # first sector
pankso@5245 363 + cmpb %ah, %dh # reach head limit ?
pankso@5245 364 + jne bdendlp
pankso@5245 365 +next_cylinder:
pankso@5245 366 + movb %dh,%ah
pankso@5245 367 +# NOTE : support 256 cylinders max
pankso@5245 368 + incb %ch # next cylinder
pankso@5245 369 +read_first_sectors:
pankso@5245 370 + movb $0,%dh # first head
pankso@5245 371 +cylinder_count = 496
pankso@5245 372 + cmpb cylinder_count, %ch
pankso@5245 373 + jb bdendlp
pankso@5245 374 + cmpb $FLOPPY_CYLINDERS,%ch # reach cylinder limit ?
pankso@5245 375 + jb bdendlp
pankso@5245 376 +next_floppy:
pankso@5245 377 + movb $0,%ch # first cylinder
pankso@5245 378 + pushaw
pankso@5245 379 + movw $swap_floppy,%si
pankso@5245 380 + incb 12(%si)
pankso@5245 381 + pushw %bx
pankso@5245 382 + call puts
pankso@5245 383 + popw %bx
pankso@5245 384 +waitfloppy:
pankso@5245 385 + call wait
pankso@5245 386 + jne waitfloppydone
pankso@5245 387 + pushw %dx # some bios break dx...
pankso@5245 388 + cbw
pankso@5245 389 + int $0x13 # reset FDC
pankso@5245 390 + movw $0x201,%ax
pankso@5245 391 +# cwd
pankso@5245 392 +# movw $1,%cx
pankso@5245 393 + int $0x13 # read first sector
pankso@5245 394 + popw %dx
pankso@5245 395 + rclb $1,%ah # floppy changed 06=>0D no error 00
pankso@5245 396 + cmpb -2(%si), %ah # 0D then 00
pankso@5245 397 + jne waitfloppy # no => try again
pankso@5245 398 + incw %si
pankso@5245 399 + orb %ah,%ah # was 00 ?
pankso@5245 400 + jne waitfloppy
pankso@5245 401 +waitfloppydone:
pankso@5245 402 + popaw
pankso@5245 403 +bdendlp:
pankso@5245 404 + xchgw %ax, %bp
pankso@5245 405 + movw %cx, %fs
pankso@5245 406 +read_sectors:
pankso@5245 407 + decw %di
pankso@5245 408 +read_one_sector:
pankso@5245 409 + movw %fs, %cx
pankso@5245 410 +# al is last sector+1
pankso@5245 411 +# ah is last cylinder+1
pankso@5245 412 + movw %bp, %ax
pankso@5245 413 + incw %di
pankso@5245 414 + jnz read_sectorslp
pankso@5245 415 + pushw %ss
pankso@5245 416 + popw %es # restore es
pankso@5245 417 + movb $0x2e+3, %al # loading... message 2e = .
pankso@5245 418 +putclf:
pankso@5245 419 + subb $3, %al
pankso@5245 420 +putc:
pankso@5245 421 + movb $0xe, %ah
pankso@5245 422 + movw $7, %bx # one dot each 64k
pankso@5245 423 + int $0x10
pankso@5245 424 + cmp $0xd, %al # CR ?
pankso@5245 425 + je putclf
pankso@5245 426 + ret
pankso@5245 427 +
pankso@5245 428 +puts:
pankso@5245 429 + movb $0xd, %al # CR
pankso@5245 430 +putcs:
pankso@5245 431 + call putc
pankso@5245 432 + lodsb
pankso@5245 433 + orb %al,%al # end of string is \0
pankso@5245 434 + jnz putcs
pankso@5245 435 + ret
pankso@5245 436 +
pankso@5245 437 +clock = 0x46C
pankso@5245 438 +wait:
pankso@5245 439 +wait4key:
pankso@5245 440 + movw $clock, %di
pankso@5245 441 +#define DELAY 5
pankso@5245 442 + movb $(DELAY*182)/10,%cl
pankso@5245 443 + addb %gs:(%di),%cl
pankso@5245 444 +waitkbd:
pankso@5245 445 + movw $0x10D, %ax # test keyboard, timeout => CR
pankso@5245 446 + cmpb %gs:(%di),%cl
pankso@5245 447 + je waitdone
pankso@5245 448 + int $0x16
pankso@5245 449 + jz waitkbd
pankso@5245 450 + cbw
pankso@5245 451 + int $0x16 # eat char
pankso@5245 452 + movw %di, %gs # disable timeout
pankso@5245 453 + incw %di # clear Z
pankso@5245 454 +waitdone:
pankso@5245 455 + ret
pankso@5245 456 +
pankso@5245 457 +#ifdef SHOW_REGS
pankso@5245 458 +regs: .asciz "X:"
pankso@5245 459 +#endif
pankso@5245 460 +
pankso@5245 461 +swap_floppy: .ascii "Insert disk 1"
pankso@5245 462 + .ascii "."
pankso@5245 463 + .byte 7,13,0
pankso@5245 464
pankso@5245 465 # Kernel attributes; used by setup. This is part 1 of the
pankso@5245 466 # header, from the old boot sector.