arch/s390/kernel/head.S

   1 /*
   2  *  arch/s390/kernel/head.S
   3  *
   4  * Copyright (C) IBM Corp. 1999,2006
   5  *
   6  *    Author(s): Hartmut Penner <hp@de.ibm.com>
   7  *               Martin Schwidefsky <schwidefsky@de.ibm.com>
   8  *               Rob van der Heij <rvdhei@iae.nl>
   9  *               Heiko Carstens <heiko.carstens@de.ibm.com>
  10  *
  11  * There are 5 different IPL methods
  12  *  1) load the image directly into ram at address 0 and do an PSW restart
  13  *  2) linload will load the image from address 0x10000 to memory 0x10000
  14  *     and start the code thru LPSW 0x0008000080010000 (VM only, deprecated)
  15  *  3) generate the tape ipl header, store the generated image on a tape
  16  *     and ipl from it
  17  *     In case of SL tape you need to IPL 5 times to get past VOL1 etc
  18  *  4) generate the vm reader ipl header, move the generated image to the
  19  *     VM reader (use option NOH!) and do a ipl from reader (VM only)
  20  *  5) direct call of start by the SALIPL loader
  21  *  We use the cpuid to distinguish between VM and native ipl
  22  *  params for kernel are pushed to 0x10400 (see setup.h)
  23  *
  24  */
  25
  26 #include <linux/init.h>
  27 #include <asm/setup.h>
  28 #include <asm/lowcore.h>
  29 #include <asm/asm-offsets.h>
  30 #include <asm/thread_info.h>
  31 #include <asm/page.h>
  32
  33 #ifdef CONFIG_64BIT
  34 #define ARCH_OFFSET     4
  35 #else
  36 #define ARCH_OFFSET     0
  37 #endif
  38
  39 __HEAD
  40 #ifndef CONFIG_IPL
  41         .org   0
  42         .long  0x00080000,0x80000000+startup    # Just a restart PSW
  43 #else
  44 #ifdef CONFIG_IPL_TAPE
  45 #define IPL_BS 1024
  46         .org   0
  47         .long  0x00080000,0x80000000+iplstart   # The first 24 bytes are loaded
  48         .long  0x27000000,0x60000001            # by ipl to addresses 0-23.
  49         .long  0x02000000,0x20000000+IPL_BS     # (a PSW and two CCWs).
  50         .long  0x00000000,0x00000000            # external old psw
  51         .long  0x00000000,0x00000000            # svc old psw
  52         .long  0x00000000,0x00000000            # program check old psw
  53         .long  0x00000000,0x00000000            # machine check old psw
  54         .long  0x00000000,0x00000000            # io old psw
  55         .long  0x00000000,0x00000000
  56         .long  0x00000000,0x00000000
  57         .long  0x00000000,0x00000000
  58         .long  0x000a0000,0x00000058            # external new psw
  59         .long  0x000a0000,0x00000060            # svc new psw
  60         .long  0x000a0000,0x00000068            # program check new psw
  61         .long  0x000a0000,0x00000070            # machine check new psw
  62         .long  0x00080000,0x80000000+.Lioint    # io new psw
  63
  64         .org   0x100
  65 #
  66 # subroutine for loading from tape
  67 # Paramters:
  68 #  R1 = device number
  69 #  R2 = load address
  70 .Lloader:
  71         st      %r14,.Lldret
  72         la      %r3,.Lorbread           # r3 = address of orb
  73         la      %r5,.Lirb               # r5 = address of irb
  74         st      %r2,.Lccwread+4         # initialize CCW data addresses
  75         lctl    %c6,%c6,.Lcr6
  76         slr     %r2,%r2
  77 .Lldlp:
  78         la      %r6,3                   # 3 retries
  79 .Lssch:
  80         ssch    0(%r3)                  # load chunk of IPL_BS bytes
  81         bnz     .Llderr
  82 .Lw4end:
  83         bas     %r14,.Lwait4io
  84         tm      8(%r5),0x82             # do we have a problem ?
  85         bnz     .Lrecov
  86         slr     %r7,%r7
  87         icm     %r7,3,10(%r5)           # get residual count
  88         lcr     %r7,%r7
  89         la      %r7,IPL_BS(%r7)         # IPL_BS-residual=#bytes read
  90         ar      %r2,%r7                 # add to total size
  91         tm      8(%r5),0x01             # found a tape mark ?
  92         bnz     .Ldone
  93         l       %r0,.Lccwread+4         # update CCW data addresses
  94         ar      %r0,%r7
  95         st      %r0,.Lccwread+4
  96         b       .Lldlp
  97 .Ldone:
  98         l       %r14,.Lldret
  99         br      %r14                    # r2 contains the total size
 100 .Lrecov:
 101         bas     %r14,.Lsense            # do the sensing
 102         bct     %r6,.Lssch              # dec. retry count & branch
 103         b       .Llderr
 104 #
 105 # Sense subroutine
 106 #
 107 .Lsense:
 108         st      %r14,.Lsnsret
 109         la      %r7,.Lorbsense
 110         ssch    0(%r7)                  # start sense command
 111         bnz     .Llderr
 112         bas     %r14,.Lwait4io
 113         l       %r14,.Lsnsret
 114         tm      8(%r5),0x82             # do we have a problem ?
 115         bnz     .Llderr
 116         br      %r14
 117 #
 118 # Wait for interrupt subroutine
 119 #
 120 .Lwait4io:
 121         lpsw    .Lwaitpsw
 122 .Lioint:
 123         c       %r1,0xb8                # compare subchannel number
 124         bne     .Lwait4io
 125         tsch    0(%r5)
 126         slr     %r0,%r0
 127         tm      8(%r5),0x82             # do we have a problem ?
 128         bnz     .Lwtexit
 129         tm      8(%r5),0x04             # got device end ?
 130         bz      .Lwait4io
 131 .Lwtexit:
 132         br      %r14
 133 .Llderr:
 134         lpsw    .Lcrash
 135
 136         .align  8
 137 .Lorbread:
 138         .long   0x00000000,0x0080ff00,.Lccwread
 139         .align  8
 140 .Lorbsense:
 141         .long   0x00000000,0x0080ff00,.Lccwsense
 142         .align  8
 143 .Lccwread:
 144         .long   0x02200000+IPL_BS,0x00000000
 145 .Lccwsense:
 146         .long   0x04200001,0x00000000
 147 .Lwaitpsw:
 148         .long   0x020a0000,0x80000000+.Lioint
 149
 150 .Lirb:  .long   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
 151 .Lcr6:  .long   0xff000000
 152         .align  8
 153 .Lcrash:.long   0x000a0000,0x00000000
 154 .Lldret:.long   0
 155 .Lsnsret: .long 0
 156 #endif  /* CONFIG_IPL_TAPE */
 157
 158 #ifdef CONFIG_IPL_VM
 159 #define IPL_BS  0x730
 160         .org    0
 161         .long   0x00080000,0x80000000+iplstart  # The first 24 bytes are loaded
 162         .long   0x02000018,0x60000050           # by ipl to addresses 0-23.
 163         .long   0x02000068,0x60000050           # (a PSW and two CCWs).
 164         .fill   80-24,1,0x40                    # bytes 24-79 are discarded !!
 165         .long   0x020000f0,0x60000050           # The next 160 byte are loaded
 166         .long   0x02000140,0x60000050           # to addresses 0x18-0xb7
 167         .long   0x02000190,0x60000050           # They form the continuation
 168         .long   0x020001e0,0x60000050           # of the CCW program started
 169         .long   0x02000230,0x60000050           # by ipl and load the range
 170         .long   0x02000280,0x60000050           # 0x0f0-0x730 from the image
 171         .long   0x020002d0,0x60000050           # to the range 0x0f0-0x730
 172         .long   0x02000320,0x60000050           # in memory. At the end of
 173         .long   0x02000370,0x60000050           # the channel program the PSW
 174         .long   0x020003c0,0x60000050           # at location 0 is loaded.
 175         .long   0x02000410,0x60000050           # Initial processing starts
 176         .long   0x02000460,0x60000050           # at 0xf0 = iplstart.
 177         .long   0x020004b0,0x60000050
 178         .long   0x02000500,0x60000050
 179         .long   0x02000550,0x60000050
 180         .long   0x020005a0,0x60000050
 181         .long   0x020005f0,0x60000050
 182         .long   0x02000640,0x60000050
 183         .long   0x02000690,0x60000050
 184         .long   0x020006e0,0x20000050
 185
 186         .org    0xf0
 187 #
 188 # subroutine for loading cards from the reader
 189 #
 190 .Lloader:
 191         la      %r3,.Lorb               # r2 = address of orb into r2
 192         la      %r5,.Lirb               # r4 = address of irb
 193         la      %r6,.Lccws
 194         la      %r7,20
 195 .Linit:
 196         st      %r2,4(%r6)              # initialize CCW data addresses
 197         la      %r2,0x50(%r2)
 198         la      %r6,8(%r6)
 199         bct     7,.Linit
 200
 201         lctl    %c6,%c6,.Lcr6           # set IO subclass mask
 202         slr     %r2,%r2
 203 .Lldlp:
 204         ssch    0(%r3)                  # load chunk of 1600 bytes
 205         bnz     .Llderr
 206 .Lwait4irq:
 207         mvc     0x78(8),.Lnewpsw        # set up IO interrupt psw
 208         lpsw    .Lwaitpsw
 209 .Lioint:
 210         c       %r1,0xb8                # compare subchannel number
 211         bne     .Lwait4irq
 212         tsch    0(%r5)
 213
 214         slr     %r0,%r0
 215         ic      %r0,8(%r5)              # get device status
 216         chi     %r0,8                   # channel end ?
 217         be      .Lcont
 218         chi     %r0,12                  # channel end + device end ?
 219         be      .Lcont
 220
 221         l       %r0,4(%r5)
 222         s       %r0,8(%r3)              # r0/8 = number of ccws executed
 223         mhi     %r0,10                  # *10 = number of bytes in ccws
 224         lh      %r3,10(%r5)             # get residual count
 225         sr      %r0,%r3                 # #ccws*80-residual=#bytes read
 226         ar      %r2,%r0
 227
 228         br      %r14                    # r2 contains the total size
 229
 230 .Lcont:
 231         ahi     %r2,0x640               # add 0x640 to total size
 232         la      %r6,.Lccws
 233         la      %r7,20
 234 .Lincr:
 235         l       %r0,4(%r6)              # update CCW data addresses
 236         ahi     %r0,0x640
 237         st      %r0,4(%r6)
 238         ahi     %r6,8
 239         bct     7,.Lincr
 240
 241         b       .Lldlp
 242 .Llderr:
 243         lpsw    .Lcrash
 244
 245         .align  8
 246 .Lorb:  .long   0x00000000,0x0080ff00,.Lccws
 247 .Lirb:  .long   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
 248 .Lcr6:  .long   0xff000000
 249 .Lloadp:.long   0,0
 250         .align  8
 251 .Lcrash:.long   0x000a0000,0x00000000
 252 .Lnewpsw:
 253         .long   0x00080000,0x80000000+.Lioint
 254 .Lwaitpsw:
 255         .long   0x020a0000,0x80000000+.Lioint
 256
 257         .align  8
 258 .Lccws: .rept   19
 259         .long   0x02600050,0x00000000
 260         .endr
 261         .long   0x02200050,0x00000000
 262 #endif  /* CONFIG_IPL_VM */
 263
 264 iplstart:
 265         lh      %r1,0xb8                # test if subchannel number
 266         bct     %r1,.Lnoload            #  is valid
 267         l       %r1,0xb8                # load ipl subchannel number
 268         la      %r2,IPL_BS              # load start address
 269         bas     %r14,.Lloader           # load rest of ipl image
 270         l       %r12,.Lparm             # pointer to parameter area
 271         st      %r1,IPL_DEVICE+ARCH_OFFSET-PARMAREA(%r12) # save ipl device number
 272
 273 #
 274 # load parameter file from ipl device
 275 #
 276 .Lagain1:
 277         l       %r2,.Linitrd            # ramdisk loc. is temp
 278         bas     %r14,.Lloader           # load parameter file
 279         ltr     %r2,%r2                 # got anything ?
 280         bz      .Lnopf
 281         chi     %r2,895
 282         bnh     .Lnotrunc
 283         la      %r2,895
 284 .Lnotrunc:
 285         l       %r4,.Linitrd
 286         clc     0(3,%r4),.L_hdr         # if it is HDRx
 287         bz      .Lagain1                # skip dataset header
 288         clc     0(3,%r4),.L_eof         # if it is EOFx
 289         bz      .Lagain1                # skip dateset trailer
 290         la      %r5,0(%r4,%r2)
 291         lr      %r3,%r2
 292 .Lidebc:
 293         tm      0(%r5),0x80             # high order bit set ?
 294         bo      .Ldocv                  #  yes -> convert from EBCDIC
 295         ahi     %r5,-1
 296         bct     %r3,.Lidebc
 297         b       .Lnocv
 298 .Ldocv:
 299         l       %r3,.Lcvtab
 300         tr      0(256,%r4),0(%r3)       # convert parameters to ascii
 301         tr      256(256,%r4),0(%r3)
 302         tr      512(256,%r4),0(%r3)
 303         tr      768(122,%r4),0(%r3)
 304 .Lnocv: la      %r3,COMMAND_LINE-PARMAREA(%r12) # load adr. of command line
 305         mvc     0(256,%r3),0(%r4)
 306         mvc     256(256,%r3),256(%r4)
 307         mvc     512(256,%r3),512(%r4)
 308         mvc     768(122,%r3),768(%r4)
 309         slr     %r0,%r0
 310         b       .Lcntlp
 311 .Ldelspc:
 312         ic      %r0,0(%r2,%r3)
 313         chi     %r0,0x20                # is it a space ?
 314         be      .Lcntlp
 315         ahi     %r2,1
 316         b       .Leolp
 317 .Lcntlp:
 318         brct    %r2,.Ldelspc
 319 .Leolp:
 320         slr     %r0,%r0
 321         stc     %r0,0(%r2,%r3)          # terminate buffer
 322 .Lnopf:
 323
 324 #
 325 # load ramdisk from ipl device
 326 #
 327 .Lagain2:
 328         l       %r2,.Linitrd            # addr of ramdisk
 329         st      %r2,INITRD_START+ARCH_OFFSET-PARMAREA(%r12)
 330         bas     %r14,.Lloader           # load ramdisk
 331         st      %r2,INITRD_SIZE+ARCH_OFFSET-PARMAREA(%r12) # store size of rd
 332         ltr     %r2,%r2
 333         bnz     .Lrdcont
 334         st      %r2,INITRD_START+ARCH_OFFSET-PARMAREA(%r12) # no ramdisk found
 335 .Lrdcont:
 336         l       %r2,.Linitrd
 337
 338         clc     0(3,%r2),.L_hdr         # skip HDRx and EOFx
 339         bz      .Lagain2
 340         clc     0(3,%r2),.L_eof
 341         bz      .Lagain2
 342
 343 #ifdef CONFIG_IPL_VM
 344 #
 345 # reset files in VM reader
 346 #
 347         stidp   __LC_CPUID              # store cpuid
 348         tm      __LC_CPUID,0xff         # running VM ?
 349         bno     .Lnoreset
 350         la      %r2,.Lreset
 351         lhi     %r3,26
 352         diag    %r2,%r3,8
 353         la      %r5,.Lirb
 354         stsch   0(%r5)                  # check if irq is pending
 355         tm      30(%r5),0x0f            # by verifying if any of the
 356         bnz     .Lwaitforirq            # activity or status control
 357         tm      31(%r5),0xff            # bits is set in the schib
 358         bz      .Lnoreset
 359 .Lwaitforirq:
 360         mvc     0x78(8),.Lrdrnewpsw     # set up IO interrupt psw
 361 .Lwaitrdrirq:
 362         lpsw    .Lrdrwaitpsw
 363 .Lrdrint:
 364         c       %r1,0xb8                # compare subchannel number
 365         bne     .Lwaitrdrirq
 366         la      %r5,.Lirb
 367         tsch    0(%r5)
 368 .Lnoreset:
 369         b       .Lnoload
 370
 371         .align  8
 372 .Lrdrnewpsw:
 373         .long   0x00080000,0x80000000+.Lrdrint
 374 .Lrdrwaitpsw:
 375         .long   0x020a0000,0x80000000+.Lrdrint
 376 #endif
 377
 378 #
 379 # everything loaded, go for it
 380 #
 381 .Lnoload:
 382         l       %r1,.Lstartup
 383         br      %r1
 384
 385 .Linitrd:.long _end + 0x400000          # default address of initrd
 386 .Lparm: .long  PARMAREA
 387 .Lstartup: .long startup
 388 .Lcvtab:.long   _ebcasc                 # ebcdic to ascii table
 389 .Lreset:.byte   0xc3,0xc8,0xc1,0xd5,0xc7,0xc5,0x40,0xd9,0xc4,0xd9,0x40
 390         .byte   0xc1,0xd3,0xd3,0x40,0xd2,0xc5,0xc5,0xd7,0x40,0xd5,0xd6
 391         .byte   0xc8,0xd6,0xd3,0xc4     # "change rdr all keep nohold"
 392 .L_eof: .long   0xc5d6c600       /* C'EOF' */
 393 .L_hdr: .long   0xc8c4d900       /* C'HDR' */
 394
 395 #endif  /* CONFIG_IPL */
 396
 397 #
 398 # SALIPL loader support. Based on a patch by Rob van der Heij.
 399 # This entry point is called directly from the SALIPL loader and
 400 # doesn't need a builtin ipl record.
 401 #
 402         .org    0x800
 403         .globl  start
 404 start:
 405         stm     %r0,%r15,0x07b0         # store registers
 406         basr    %r12,%r0
 407 .base:
 408         l       %r11,.parm
 409         l       %r8,.cmd                # pointer to command buffer
 410
 411         ltr     %r9,%r9                 # do we have SALIPL parameters?
 412         bp      .sk8x8
 413
 414         mvc     0(64,%r8),0x00b0        # copy saved registers
 415         xc      64(240-64,%r8),0(%r8)   # remainder of buffer
 416         tr      0(64,%r8),.lowcase
 417         b       .gotr
 418 .sk8x8:
 419         mvc     0(240,%r8),0(%r9)       # copy iplparms into buffer
 420 .gotr:
 421         l       %r10,.tbl               # EBCDIC to ASCII table
 422         tr      0(240,%r8),0(%r10)
 423         slr     %r0,%r0
 424         st      %r0,INITRD_SIZE+ARCH_OFFSET-PARMAREA(%r11)
 425         st      %r0,INITRD_START+ARCH_OFFSET-PARMAREA(%r11)
 426         j       startup                 # continue with startup
 427 .tbl:   .long   _ebcasc                 # translate table
 428 .cmd:   .long   COMMAND_LINE            # address of command line buffer
 429 .parm:  .long   PARMAREA
 430 .lowcase:
 431         .byte 0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07
 432         .byte 0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f
 433         .byte 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17
 434         .byte 0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f
 435         .byte 0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27
 436         .byte 0x28,0x29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f
 437         .byte 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37
 438         .byte 0x38,0x39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f
 439         .byte 0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47
 440         .byte 0x48,0x49,0x4a,0x4b,0x4c,0x4d,0x4e,0x4f
 441         .byte 0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57
 442         .byte 0x58,0x59,0x5a,0x5b,0x5c,0x5d,0x5e,0x5f
 443         .byte 0x60,0x61,0x62,0x63,0x64,0x65,0x66,0x67
 444         .byte 0x68,0x69,0x6a,0x6b,0x6c,0x6d,0x6e,0x6f
 445         .byte 0x70,0x71,0x72,0x73,0x74,0x75,0x76,0x77
 446         .byte 0x78,0x79,0x7a,0x7b,0x7c,0x7d,0x7e,0x7f
 447
 448         .byte 0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87
 449         .byte 0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f
 450         .byte 0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97
 451         .byte 0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f
 452         .byte 0xa0,0xa1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7
 453         .byte 0xa8,0xa9,0xaa,0xab,0xac,0xad,0xae,0xaf
 454         .byte 0xb0,0xb1,0xb2,0xb3,0xb4,0xb5,0xb6,0xb7
 455         .byte 0xb8,0xb9,0xba,0xbb,0xbc,0xbd,0xbe,0xbf
 456         .byte 0xc0,0x81,0x82,0x83,0x84,0x85,0x86,0x87   # .abcdefg
 457         .byte 0x88,0x89,0xca,0xcb,0xcc,0xcd,0xce,0xcf   # hi
 458         .byte 0xd0,0x91,0x92,0x93,0x94,0x95,0x96,0x97   # .jklmnop
 459         .byte 0x98,0x99,0xda,0xdb,0xdc,0xdd,0xde,0xdf   # qr
 460         .byte 0xe0,0xe1,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7   # ..stuvwx
 461         .byte 0xa8,0xa9,0xea,0xeb,0xec,0xed,0xee,0xef   # yz
 462         .byte 0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7
 463         .byte 0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff
 464
 465 #
 466 # startup-code at 0x10000, running in absolute addressing mode
 467 # this is called either by the ipl loader or directly by PSW restart
 468 # or linload or SALIPL
 469 #
 470         .org    0x10000
 471 startup:basr    %r13,0                  # get base
 472 .LPG0:
 473         xc      0x200(256),0x200        # partially clear lowcore
 474         xc      0x300(256),0x300
 475         l       %r1,5f-.LPG0(%r13)
 476         stck    0(%r1)
 477         spt     6f-.LPG0(%r13)
 478         mvc     __LC_LAST_UPDATE_CLOCK(8),0(%r1)
 479         mvc     __LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
 480         mvc     __LC_EXIT_TIMER(8),5f-.LPG0(%r13)
 481 #ifndef CONFIG_MARCH_G5
 482         # check processor version against MARCH_{G5,Z900,Z990,Z9_109,Z10}
 483         stidp   __LC_CPUID              # store cpuid
 484         lhi     %r0,(3f-2f) / 2
 485         la      %r1,2f-.LPG0(%r13)
 486 0:      clc     __LC_CPUID+4(2),0(%r1)
 487         jne     3f
 488         lpsw    1f-.LPG0(13)            # machine type not good enough, crash
 489         .align 16
 490 1:      .long   0x000a0000,0x00000000
 491 2:
 492 #if defined(CONFIG_MARCH_Z10)
 493         .short 0x9672, 0x2064, 0x2066, 0x2084, 0x2086, 0x2094, 0x2096
 494 #elif defined(CONFIG_MARCH_Z9_109)
 495         .short 0x9672, 0x2064, 0x2066, 0x2084, 0x2086
 496 #elif defined(CONFIG_MARCH_Z990)
 497         .short 0x9672, 0x2064, 0x2066
 498 #elif defined(CONFIG_MARCH_Z900)
 499         .short 0x9672
 500 #endif
 501 3:      la      %r1,2(%r1)
 502         brct    %r0,0b
 503 #endif
 504
 505         l       %r13,4f-.LPG0(%r13)
 506         b       0(%r13)
 507         .align  4
 508 4:      .long   startup_continue
 509 5:      .long   sched_clock_base_cc
 510         .align  8
 511 6:      .long   0x7fffffff,0xffffffff
 512
 513 #
 514 # params at 10400 (setup.h)
 515 #
 516         .org    PARMAREA
 517         .long   0,0                     # IPL_DEVICE
 518         .long   0,0                     # INITRD_START
 519         .long   0,0                     # INITRD_SIZE
 520
 521         .org    COMMAND_LINE
 522         .byte   "root=/dev/ram0 ro"
 523         .byte   0
 524
 525 #ifdef CONFIG_64BIT
 526 #include "head64.S"
 527 #else
 528 #include "head31.S"
 529 #endif