wok annotate linux/stuff/linux-header-2.6.33.2.u @ rev 5383

linux/boot: fix floppy full case
author Pascal Bellard <pascal.bellard@slitaz.org>
date Sat May 01 15:45:41 2010 +0200 (2010-05-01)
parents a2cb144efd42
children
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
pascal@5383 12 @@ -27,6 +27,8 @@
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
pascal@5383 21 @@ -40,53 +42,412 @@
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
pascal@5383 43 +
pankso@5245 44 + pushw %es
pankso@5245 45 + popw %ss # %ss and %es already contain INITSEG
pankso@5245 46 + movw %di, %sp # put stack at INITSEG:stacktop-...
pascal@5383 47 +
pankso@5245 48 +# Many BIOS's default disk parameter tables will not recognize
pankso@5245 49 +# multi-sector reads beyond the maximum sector number specified
pankso@5245 50 +# in the default diskette parameter tables - this may mean 7
pankso@5245 51 +# sectors in some cases.
pankso@5245 52 +#
pankso@5245 53 +# Since single sector reads are slow and out of the question,
pankso@5245 54 +# we must take care of this by creating new parameter tables
pankso@5245 55 +# (for the first disk) in RAM. We can set the maximum sector
pankso@5245 56 +# count to 36 - the most we will encounter on an ED 2.88.
pankso@5245 57 +#
pankso@5245 58 +# High doesn't hurt. Low does. Let's use the max: 63
pankso@5245 59 +#
pankso@5245 60 +# Segments are as follows: %es = %ss = INITSEG,
pascal@5383 61 +
pankso@5245 62 + xorw %ax, %ax # %ax = 0
pankso@5245 63 + movw $zeroed/2, %cx # clear gdt + offset, %ds, limits
pankso@5245 64 + rep # don't worry about cld
pankso@5245 65 + stosw # already done above
pankso@5245 66 + popw %bx # offset = 0
pankso@5245 67 + popw %ds # %ds = 0
pankso@5245 68 + popw %gs # %gs = 0
pascal@5383 69 +
pankso@5245 70 + movb setup_sects+0x7C00, %al # read bootsector + setup (%ds = 0)
pankso@5245 71 + incw %ax
pankso@5245 72 +
pankso@5245 73 + pushw %es
pankso@5245 74 + pushw %di # %ds:%bx+0x78 is parameter table address
pankso@5245 75 + ldsw 0x78(%bx), %si # %ds:%si is source
pankso@5245 76 + movb $6, %cl # copy 12 bytes
pankso@5245 77 + rep # don't worry about cld
pankso@5245 78 + movsw # already done above
pankso@5245 79 + popl %gs:0x78(%bx) # update parameter table address
pankso@5245 80 + pushw %es
pankso@5245 81 + popw %ds # now %ds = %es = %ss = INITSEG
pankso@5245 82 + movb $63, 0x4-12(%di) # patch sector count, %di = stacktop
pankso@5245 83 + cli
pankso@5245 84 +
pankso@5245 85 + xchg %ax, %di # sector count
pankso@5245 86 + popw %ax # limits = 0
pankso@5245 87 + incw %cx # cylinder 0, sector 1
pankso@5245 88 + call read_first_sectors # read setup
pankso@5245 89 +
pankso@5245 90 +offset_version = 0xE
pankso@5245 91 + movw $0x200,%si
pankso@5245 92 + addw offset_version(%si),%si # starting protocol 2.00, Kernel 1.3.73
pascal@5383 93 + call putstr # show which kernel we are loading
pankso@5245 94 +
pankso@5245 95 +# The cmdline can be entered and modifed at boot time.
pankso@5245 96 +# Only characters before the cursor are passed to the kernel.
pankso@5245 97 + popw %bx # clear %bx
pankso@5245 98 + orw cmd_line_ptr, %bx
pankso@5245 99 + jz nocmdline
pankso@5245 100 + pushw %bx
pascal@5383 101 + incw %di
pascal@5383 102 + call read_sectors
pankso@5245 103 + popw %si
pascal@5383 104 + call putstr
pankso@5245 105 +#ifdef EDIT_CMDLINE
pankso@5245 106 +cmdlp:
pankso@5245 107 + movb $0x20, %al # clear end of line
pankso@5245 108 + int $0x10 # with Space
pankso@5245 109 + movb $8, %al # and BackSpace
pascal@5383 110 + int $0x10
pankso@5245 111 + decw %si
pankso@5245 112 +cmdget:
pankso@5245 113 + call wait4key
pankso@5245 114 + cmpb $8, %al # BackSpace ?
pankso@5245 115 + je cmdbs
pankso@5245 116 + movb %al, (%si) # store char
pankso@5245 117 + lodsw # %si += 2
pankso@5245 118 +cmdbs:
pankso@5245 119 +#if 1
pankso@5245 120 + cmpw %si,cmd_line_ptr
pankso@5245 121 + je cmdget
pankso@5245 122 +#endif
pankso@5245 123 + call putc # set %ah and %bx
pankso@5245 124 + cmpb $10, %al # Enter ?
pankso@5245 125 + jne cmdlp
pankso@5245 126 + movb %bh,-2(%si) # set end of string and remove CR
pankso@5245 127 +endcmdline:
pankso@5245 128 +#endif
pankso@5245 129 +nocmdline:
pankso@5245 130
pascal@5383 131 - # Normalize the start address
pascal@5383 132 - ljmp $BOOTSEG, $start2
pascal@5383 133 -
pascal@5383 134 -start2:
pascal@5383 135 - movw %cs, %ax
pascal@5383 136 - movw %ax, %ds
pascal@5383 137 - movw %ax, %es
pascal@5383 138 - movw %ax, %ss
pascal@5383 139 - xorw %sp, %sp
pascal@5383 140 - sti
pascal@5383 141 - cld
pascal@5383 142 -
pascal@5383 143 - movw $bugger_off_msg, %si
pankso@5245 144 +# This routine loads the system at address SYSSEG, making sure
pankso@5245 145 +# no 64kB boundaries are crossed. We try to load it as fast as
pankso@5245 146 +# possible, loading whole tracks whenever we can.
pascal@5383 147 +
pankso@5245 148 +ramdisk_image = 0x0218
pankso@5245 149 +ramdisk_size = 0x021C
pankso@5245 150 + movw %sp, %si # for bootsect_gdt
pankso@5245 151 + decw 16(%si) # bootsect_src = 64Kb
pankso@5245 152 + decw 24(%si) # bootsect_dst = 64Kb
pankso@5245 153 + movw $syssize, %di
pankso@5245 154 +type_of_loader = 0x210
pankso@5245 155 +loadflags = 0x211
pankso@5245 156 +heap_end_ptr = 0x224
pankso@5245 157 +ksyssize = 500
pankso@5245 158 + orw $0x80FF, type_of_loader-ksyssize(%di) # loader type = 0xFF
pankso@5245 159 + movw $stacktop-0x200, heap_end_ptr-ksyssize(%di)
pascal@5259 160 + movb $0x10, %al # destination = 0x100000
pankso@5245 161 + movb $5, %cl
pankso@5245 162 +initrdlp:
pascal@5259 163 + decw %ax
pankso@5245 164 + movb $0x93,%ah
pankso@5245 165 + movw %ax, 28(%si) # bootsect_dst_base+2
pankso@5245 166 + movb $(SYSSEG/4096), %al # source = SYSSEG
pankso@5245 167 + movw %ax, 20(%si) # bootsect_src_base+2
pankso@5245 168 + cbw
pankso@5245 169 + cwde
pankso@5245 170 + shlw %cl, %ax
pankso@5245 171 + decw %ax
pankso@5245 172 + addl (%di),%eax
pankso@5245 173 + shrl %cl, %eax
pankso@5245 174 +syslp:
pankso@5245 175 + pushw $SYSSEG
pankso@5245 176 + popw %es
pankso@5245 177 + movw $128,%di # 64Kb
pankso@5245 178 + subw %di, %ax # max 32M > int 15 limit
pankso@5245 179 + pushf
pankso@5245 180 + jnc not_last
pankso@5245 181 + addw %ax, %di
pankso@5245 182 +not_last:
pankso@5245 183 + xorw %bx, %bx # clear %bx
pankso@5245 184 + pushw %ax
pankso@5245 185 +#if defined(SHOW_REGS)
pankso@5245 186 + pushw %si
pankso@5245 187 + call read_sectors
pankso@5245 188 + popw %si
pankso@5245 189 +#else
pankso@5245 190 + call read_sectors
pankso@5245 191 +#endif
pankso@5245 192 + movw $0x8000, %cx # full 64K
pankso@5245 193 + movb $0x87, %ah
pankso@5245 194 + incb 28(%si) # bootsect_dst_base+2
pankso@5245 195 + int $0x15 # max 16M
pankso@5245 196 + popw %ax
pankso@5245 197 + popf
pankso@5245 198 + ja syslp
pankso@5245 199 + movw ramdisk_image+2,%ax
pankso@5245 200 + movw $ramdisk_size,%di
pankso@5245 201 + movb $9, %cl
pankso@5245 202 + cmpb %al,28(%si)
pankso@5245 203 + jb initrdlp
pascal@5383 204 +
pankso@5245 205 +# This procedure turns off the floppy drive motor, so
pankso@5245 206 +# that we enter the kernel in a known state, and
pankso@5245 207 +# don't have to worry about it later.
pascal@5383 208 +
pankso@5245 209 +#if 1
pankso@5245 210 +kill_motor:
pankso@5245 211 + xchgw %ax, %bx # reset FDC
pankso@5245 212 + int $0x13
pankso@5245 213 +#else
pankso@5245 214 +kill_motor:
pankso@5245 215 + movw $0x3f2, %dx
pankso@5245 216 + xchgw %ax, %bx
pankso@5245 217 + outb %al, %dx
pankso@5245 218 +#endif
pascal@5383 219
pascal@5383 220 -msg_loop:
pascal@5383 221 - lodsb
pascal@5383 222 - andb %al, %al
pascal@5383 223 - jz bs_die
pascal@5383 224 - movb $0xe, %ah
pascal@5383 225 - movw $7, %bx
pankso@5245 226 +# After that (everything loaded), we jump to the setup-routine
pankso@5245 227 +# loaded directly after the bootblock:
pankso@5245 228 +# Segments are as follows: %ds = %ss = INITSEG
pankso@5245 229 +
pankso@5245 230 + ljmp $SETUPSEG, $0
pankso@5245 231 +
pankso@5245 232 +# read_sectors reads %di sectors into %es:0 buffer.
pankso@5245 233 +# %es:0 is updated to the next memory location.
pankso@5245 234 +# First, sectors are read sector by sector until
pankso@5245 235 +# sector per track count is known. Then they are
pankso@5245 236 +# read track by track.
pankso@5245 237 +# Assume no error on first track.
pankso@5245 238 +
pankso@5245 239 +#define FLOPPY_CYLINDERS 80 /* 80 cylinders minimum */
pankso@5245 240 +#define FLOPPY_HEADS 2 /* 2 heads minimum */
pankso@5245 241 +#define FLOPPY_SECTORS 18 /* 18 sectors minimum */
pankso@5245 242 +
pankso@5245 243 +#ifdef SHOW_REGS
pankso@5245 244 +print_loop:
pankso@5245 245 + movb $0x6 + 'A' - 1, %al
pankso@5245 246 + subb %cl, %al
pankso@5245 247 + movw $regs, %si # caller %si is saved
pascal@5383 248 + call putcs # putc(%al) + putstr(%si)
pankso@5245 249 +# it will print out all of the registers.
pankso@5245 250 + popw %bp # load word into %si
pankso@5245 251 + jmp print_all # print %bp (status)
pankso@5245 252 +#endif
pankso@5245 253 +check_limits:
pankso@5245 254 +#ifndef SHOW_REGS
pankso@5245 255 + popw %dx
pankso@5245 256 +#endif
pankso@5245 257 + cmpb $FLOPPY_SECTORS+1, %cl # 18 sectors minimum
pankso@5245 258 + jb check_head
pankso@5245 259 + cmpb %al, %cl # max sector known ?
pankso@5245 260 + ja next_head # no -> store it
pankso@5245 261 +check_head:
pankso@5245 262 + cmpb $FLOPPY_HEADS, %dh # 2 heads minimum
pankso@5245 263 + jb check_cylinder
pankso@5245 264 + cmpb %ah, %dh # max head known ?
pankso@5245 265 + ja next_cylinder # no -> store it
pankso@5245 266 +check_cylinder:
pankso@5245 267 + pushaw
pankso@5245 268 +#ifdef SHOW_REGS
pankso@5245 269 + cmpw $0x600,%bp # disk changed ?
pankso@5245 270 + je reset_floppy
pankso@5245 271 + pushw %es # print %es (named EX)
pankso@5245 272 + pushw %dx # print %dx
pankso@5245 273 + pushw %cx # print %cx
pankso@5245 274 + pushw %bx # print %bx
pankso@5245 275 + xchgw %ax, %si
pankso@5245 276 + movb $2,%ah
pankso@5245 277 + pushw %ax # print %ax
pankso@5245 278 + movb $6,%cl
pankso@5245 279 +print_all:
pankso@5245 280 + movb $4, %ch # 4 hex digits
pankso@5245 281 +print_digit:
pankso@5245 282 + rolw $4, %bp # rotate to use low 4 bits
pankso@5245 283 + movb $0x0f, %al
pankso@5245 284 + andw %bp, %ax # %al = mask for nybble
pankso@5245 285 + addb $0x90, %al # convert %al to ascii hex
pankso@5245 286 + daa # in only four instructions!
pankso@5245 287 + adcb $0x40, %al
pankso@5245 288 + daa
pankso@5245 289 + call putc # set %ah and %bx
pankso@5245 290 + decb %ch
pankso@5245 291 + jnz print_digit
pankso@5245 292 + movb $0x20, %al # SPACE
pascal@5383 293 int $0x10
pascal@5383 294 - jmp msg_loop
pascal@5383 295 -
pascal@5383 296 -bs_die:
pascal@5383 297 - # Allow the user to press a key, then reboot
pascal@5383 298 - xorw %ax, %ax
pankso@5245 299 + loop print_loop
pankso@5245 300 + call wait
pankso@5245 301 + cbw # %ah = 0
pankso@5245 302 +reset_floppy:
pankso@5245 303 +#else
pankso@5245 304 + cbw # %ah = 0
pankso@5245 305 +#endif
pankso@5245 306 + int $0x13 # reset controler
pankso@5245 307 + popaw
pankso@5245 308 +read_sectorslp:
pankso@5245 309 + pushw %dx # some bios break dx...
pankso@5245 310 + pushw %ax # limits
pankso@5245 311 + subb %cl, %al # sectors remaining in track
pankso@5245 312 + ja tolastsect
pankso@5245 313 + movb $1, %al # 1 sector mini
pankso@5245 314 +tolastsect:
pankso@5245 315 + cbw
pankso@5245 316 + cmpw %di, %ax
pankso@5245 317 + jb more1trk
pankso@5245 318 + movw %di, %ax # sectors to read
pankso@5245 319 +more1trk:
pankso@5245 320 + pushw %ax # save context
pankso@5245 321 + movb $2, %ah # cmd: read chs
pankso@5245 322 + int $0x13
pankso@5245 323 +#ifdef SHOW_REGS
pankso@5245 324 + xchgw %ax, %bp # status
pankso@5245 325 +#endif
pankso@5245 326 +# ifdef SHOW_REGS
pankso@5245 327 + popw %si # save %ax
pankso@5245 328 + popw %ax # limits
pankso@5245 329 + popw %dx
pankso@5245 330 +# else
pankso@5245 331 + popw %dx # save %ax
pankso@5245 332 + popw %ax # limits
pankso@5245 333 +# endif
pankso@5245 334 + jc check_limits
pascal@5383 335 + xchgw %ax, %bp
pankso@5245 336 +# ifdef SHOW_REGS
pankso@5245 337 +update_regs:
pascal@5383 338 + incw %cx # next sector
pascal@5383 339 + movw %cx, %fs
pascal@5383 340 + addb $2,%bh # next location
pankso@5245 341 + decw %di # update sector counter
pascal@5383 342 + jz putcdot
pankso@5245 343 + decw %si
pankso@5245 344 + jnz update_regs
pankso@5245 345 +# else
pascal@5383 346 + addw %dx,%cx # next sector
pascal@5383 347 + addb %dl,%bh
pascal@5383 348 + addb %dl,%bh # next location
pankso@5245 349 + subw %dx,%di # update sector counter
pankso@5245 350 + popw %dx
pascal@5383 351 + jz putcdot
pankso@5245 352 +# endif
pascal@5383 353 +read_sectors:
pascal@5383 354 + movw %fs, %cx
pascal@5383 355 + xchgw %ax, %bp
pankso@5245 356 + cmpb %al,%cl # reach sector limit ?
pankso@5245 357 + jne bdendlp
pankso@5245 358 +next_head:
pankso@5245 359 + movb %cl,%al
pankso@5245 360 + incb %dh # next head
pankso@5245 361 + movb $1,%cl # first sector
pankso@5245 362 + cmpb %ah, %dh # reach head limit ?
pankso@5245 363 + jne bdendlp
pankso@5245 364 +next_cylinder:
pankso@5245 365 + movb %dh,%ah
pankso@5245 366 +# NOTE : support 256 cylinders max
pankso@5245 367 + incb %ch # next cylinder
pankso@5245 368 +read_first_sectors:
pankso@5245 369 + movb $0,%dh # first head
pankso@5245 370 +cylinder_count = 496
pascal@5383 371 + cmpb $FLOPPY_CYLINDERS,%ch # reach cylinder limit ?
pascal@5383 372 + jb bdendlp
pankso@5245 373 + cmpb cylinder_count, %ch
pankso@5245 374 + jb bdendlp
pankso@5245 375 +next_floppy:
pankso@5245 376 + movb $0,%ch # first cylinder
pankso@5245 377 + pushaw
pankso@5245 378 + movw $swap_floppy,%si
pankso@5245 379 + incb 12(%si)
pankso@5245 380 + pushw %bx
pascal@5383 381 + call putstr
pankso@5245 382 + popw %bx
pankso@5245 383 +waitfloppy:
pankso@5245 384 + call wait
pankso@5245 385 + jne waitfloppydone
pankso@5245 386 + pushw %dx # some bios break dx...
pankso@5245 387 + cbw
pankso@5245 388 + int $0x13 # reset FDC
pankso@5245 389 + movw $0x201,%ax
pankso@5245 390 +# cwd
pankso@5245 391 +# movw $1,%cx
pankso@5245 392 + int $0x13 # read first sector
pankso@5245 393 + popw %dx
pankso@5245 394 + rclb $1,%ah # floppy changed 06=>0D no error 00
pankso@5245 395 + cmpb -2(%si), %ah # 0D then 00
pankso@5245 396 + jne waitfloppy # no => try again
pankso@5245 397 + incw %si
pankso@5245 398 + orb %ah,%ah # was 00 ?
pankso@5245 399 + jne waitfloppy
pankso@5245 400 +waitfloppydone:
pankso@5245 401 + popaw
pankso@5245 402 +bdendlp:
pascal@5383 403 + jmp read_sectorslp
pascal@5383 404 +
pascal@5383 405 +putcdot:
pankso@5245 406 + pushw %ss
pankso@5245 407 + popw %es # restore es
pankso@5245 408 + movb $0x2e+3, %al # loading... message 2e = .
pankso@5245 409 +putclf:
pankso@5245 410 + subb $3, %al
pankso@5245 411 +putc:
pankso@5245 412 + movb $0xe, %ah
pankso@5245 413 + movw $7, %bx # one dot each 64k
pankso@5245 414 + int $0x10
pankso@5245 415 + cmp $0xd, %al # CR ?
pankso@5245 416 + je putclf
pankso@5245 417 + ret
pankso@5245 418 +
pascal@5383 419 +putstr:
pankso@5245 420 + movb $0xd, %al # CR
pankso@5245 421 +putcs:
pankso@5245 422 + call putc
pankso@5245 423 + lodsb
pankso@5245 424 + orb %al,%al # end of string is \0
pankso@5245 425 + jnz putcs
pankso@5245 426 + ret
pankso@5245 427 +
pankso@5245 428 +clock = 0x46C
pankso@5245 429 +wait:
pankso@5245 430 +wait4key:
pankso@5245 431 + movw $clock, %di
pankso@5245 432 +#define DELAY 5
pankso@5245 433 + movb $(DELAY*182)/10,%cl
pankso@5245 434 + addb %gs:(%di),%cl
pankso@5245 435 +waitkbd:
pankso@5245 436 + movw $0x10D, %ax # test keyboard, timeout => CR
pankso@5245 437 + cmpb %gs:(%di),%cl
pankso@5245 438 + je waitdone
pascal@5383 439 int $0x16
pascal@5383 440 - int $0x19
pankso@5245 441 + jz waitkbd
pankso@5245 442 + cbw
pankso@5245 443 + int $0x16 # eat char
pankso@5245 444 + movw %di, %gs # disable timeout
pankso@5245 445 + incw %di # clear Z
pankso@5245 446 +waitdone:
pankso@5245 447 + ret
pascal@5383 448
pascal@5383 449 - # int 0x19 should never return. In case it does anyway,
pascal@5383 450 - # invoke the BIOS reset code...
pascal@5383 451 - ljmp $0xf000,$0xfff0
pascal@5383 452 -
pascal@5383 453 - .section ".bsdata", "a"
pascal@5383 454 -bugger_off_msg:
pascal@5383 455 - .ascii "Direct booting from floppy is no longer supported.\r\n"
pascal@5383 456 - .ascii "Please use a boot loader program instead.\r\n"
pascal@5383 457 - .ascii "\n"
pascal@5383 458 - .ascii "Remove disk and press any key to reboot . . .\r\n"
pascal@5383 459 - .byte 0
pankso@5245 460 +#ifdef SHOW_REGS
pascal@5383 461 +regs: .asciz "X:"
pankso@5245 462 +#endif
pascal@5383 463
pankso@5245 464 +swap_floppy: .ascii "Insert disk 1"
pankso@5245 465 + .ascii "."
pankso@5245 466 + .byte 7,13,0
pankso@5245 467
pankso@5245 468 # Kernel attributes; used by setup. This is part 1 of the
pankso@5245 469 # header, from the old boot sector.