memdisk/setup.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2001-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 #include <stdint.h>
  14 #include "e820.h"
  15 #include "conio.h"
  16 #include "version.h"
  17 #include "memdisk.h"
  18
  19 const char memdisk_version[] =
  20 "MEMDISK " VERSION " " DATE;
  21 const char copyright[] =
  22 "Copyright " FIRSTYEAR "-" COPYYEAR " H. Peter Anvin";
  23
  24 extern const char _binary_memdisk_bin_start[], _binary_memdisk_bin_end[];
  25 extern const char _binary_memdisk_bin_size[]; /* Weird, I know */
  26
  27 struct memdisk_header {
  28   uint16_t int13_offs;
  29   uint16_t int15_offs;
  30   uint16_t patch_offs;
  31   uint16_t total_size;
  32   uint16_t iret_offs;
  33 };
  34
  35 /* The Disk Parameter Table may be required */
  36 typedef union {
  37   struct hd_dpt {
  38     uint16_t max_cyl;           /* Max cylinder */
  39     uint8_t max_head;           /* Max head */
  40     uint8_t junk1[5];           /* Obsolete junk, leave at zero */
  41     uint8_t ctrl;               /* Control byte */
  42     uint8_t junk2[7];           /* More obsolete junk */
  43   } hd;
  44   struct fd_dpt {
  45     uint8_t specify1;           /* "First specify byte" */
  46     uint8_t specify2;           /* "Second specify byte" */
  47     uint8_t delay;              /* Delay until motor turn off */
  48     uint8_t sectors;            /* Sectors/track */
  49
  50     uint8_t bps;                /* Bytes/sector (02h = 512) */
  51     uint8_t isgap;              /* Length of intersector gap */
  52     uint8_t dlen;               /* Data length (0FFh) */
  53     uint8_t fgap;               /* Formatting gap */
  54
  55     uint8_t ffill;              /* Format fill byte */
  56     uint8_t settle;             /* Head settle time (ms) */
  57     uint8_t mstart;             /* Motor start time */
  58     uint8_t _pad1;              /* Padding */
  59
  60     uint32_t old_fd_dpt;        /* Extension: pointer to old INT 1Eh */
  61   } fd;
  62 } dpt_t;
  63
  64 /* EDD disk parameter table */
  65 struct edd_dpt {
  66   uint16_t len;                 /* Length of table */
  67   uint16_t flags;               /* Information flags */
  68   uint32_t c;                   /* Physical cylinders (count!) */
  69   uint32_t h;                   /* Physical heads (count!) */
  70   uint32_t s;                   /* Physical sectors/track (count!) */
  71   uint64_t sectors;             /* Total sectors */
  72   uint16_t bytespersec;         /* Bytes/sector */
  73   uint16_t dpte_off, dpte_seg;  /* DPTE pointer */
  74 };
  75
  76 struct patch_area {
  77   uint32_t diskbuf;
  78   uint32_t disksize;
  79   uint16_t cmdline_off, cmdline_seg;
  80
  81   uint32_t oldint13;
  82   uint32_t oldint15;
  83
  84   uint16_t olddosmem;
  85   uint8_t  bootloaderid;
  86   uint8_t  maxint13func;
  87 #define MAXINT13_NOEDD  0x16
  88
  89   uint8_t  _pad[2];
  90   uint16_t memint1588;
  91
  92   uint16_t cylinders;
  93   uint16_t heads;
  94   uint32_t sectors;
  95
  96   uint32_t mem1mb;
  97   uint32_t mem16mb;
  98
  99   uint8_t  driveno;
 100   uint8_t  drivetype;
 101   uint8_t  drivecnt;
 102   uint8_t  configflags;
 103
 104 #define CONFIG_READONLY 0x01
 105 #define CONFIG_RAW      0x02
 106 #define CONFIG_SAFEINT  0x04
 107 #define CONFIG_BIGRAW   0x08            /* MUST be 8! */
 108
 109   uint16_t mystack;
 110   uint16_t statusptr;
 111
 112   dpt_t dpt;
 113   struct edd_dpt edd_dpt;
 114 };
 115
 116 /* This is the header in the boot sector/setup area */
 117 struct setup_header {
 118   char cmdline[0x1f1];
 119   uint8_t setup_secs;
 120   uint16_t syssize;
 121   uint16_t swap_dev;
 122   uint16_t ram_size;
 123   uint16_t vid_mode;
 124   uint16_t root_dev;
 125   uint16_t boot_flag;
 126   uint16_t jump;
 127   char header[4];
 128   uint16_t version;
 129   uint32_t realmode_swtch;
 130   uint32_t start_sys;
 131   uint8_t type_of_loader;
 132   uint8_t loadflags;
 133   uint16_t setup_move_size;
 134   uint32_t code32_start;
 135   uint32_t ramdisk_image;
 136   uint32_t ramdisk_size;
 137   uint32_t bootsect_kludge;
 138   uint16_t head_end_ptr;
 139   uint16_t pad1;
 140   uint32_t cmd_line_ptr;
 141   uint32_t initrd_addr_max;
 142   uint32_t esdi;
 143   uint32_t edx;
 144 };
 145
 146 struct setup_header * const shdr = (struct setup_header *)(LOW_SEG << 4);
 147
 148 /* Access to high memory */
 149
 150 /* Access to objects in the zero page */
 151 static inline void
 152 wrz_8(uint32_t addr, uint8_t data)
 153 {
 154   *((uint8_t *)addr) = data;
 155 }
 156 static inline void
 157 wrz_16(uint32_t addr, uint16_t data)
 158 {
 159   *((uint16_t *)addr) = data;
 160 }
 161 static inline void
 162 wrz_32(uint32_t addr, uint32_t data)
 163 {
 164   *((uint32_t *)addr) = data;
 165 }
 166 static inline uint8_t
 167 rdz_8(uint32_t addr)
 168 {
 169   return *((uint8_t *)addr);
 170 }
 171 static inline uint16_t
 172 rdz_16(uint32_t addr)
 173 {
 174   return *((uint16_t *)addr);
 175 }
 176 static inline uint32_t
 177 rdz_32(uint32_t addr)
 178 {
 179   return *((uint32_t *)addr);
 180 }
 181
 182 /* Addresses in the zero page */
 183 #define BIOS_INT13      (0x13*4) /* INT 13h vector */
 184 #define BIOS_INT15      (0x15*4) /* INT 15h vector */
 185 #define BIOS_INT1E      (0x1E*4) /* INT 1Eh vector */
 186 #define BIOS_INT40      (0x40*4) /* INT 13h vector */
 187 #define BIOS_INT41      (0x41*4) /* INT 41h vector */
 188 #define BIOS_INT46      (0x46*4) /* INT 46h vector */
 189 #define BIOS_BASEMEM    0x413    /* Amount of DOS memory */
 190 #define BIOS_EQUIP      0x410    /* BIOS equipment list */
 191 #define BIOS_HD_COUNT   0x475    /* Number of hard drives present */
 192
 193 /*
 194  * Routine to seek for a command-line item and return a pointer
 195  * to the data portion, if present
 196  */
 197
 198 /* Magic return values */
 199 #define CMD_NOTFOUND   ((char *)-1) /* Not found */
 200 #define CMD_BOOL       ((char *)-2) /* Found boolean option */
 201 #define CMD_HASDATA(X) ((int)(X) >= 0)
 202
 203 const char *getcmditem(const char *what)
 204 {
 205   const char *p;
 206   const char *wp = what;
 207   int match = 0;
 208
 209   for ( p = shdr->cmdline ; *p ; p++ ) {
 210     switch ( match ) {
 211     case 0:                     /* Ground state */
 212       if ( *p == ' ' )
 213         break;
 214
 215       wp = what;
 216       match = 1;
 217       /* Fall through */
 218
 219     case 1:                     /* Matching */
 220       if ( *wp == '\0' ) {
 221         if ( *p == '=' )
 222           return p+1;
 223         else if ( *p == ' ' )
 224           return CMD_BOOL;
 225         else {
 226           match = 2;
 227           break;
 228         }
 229       }
 230       if ( *p != *wp++ )
 231         match = 2;
 232       break;
 233
 234     case 2:                     /* Mismatch, skip rest of option */
 235       if ( *p == ' ' )
 236         match = 0;              /* Next option */
 237       break;
 238     }
 239   }
 240
 241   /* Check for matching string at end of line */
 242   if ( match == 1 && *wp == '\0' )
 243     return CMD_BOOL;
 244
 245   return CMD_NOTFOUND;
 246 }
 247
 248 /*
 249  * Check to see if this is a gzip image
 250  */
 251 #define UNZIP_ALIGN 512
 252
 253 extern void _end;               /* Symbol signalling end of data */
 254
 255 void unzip_if_needed(uint32_t *where_p, uint32_t *size_p)
 256 {
 257   uint32_t where = *where_p;
 258   uint32_t size = *size_p;
 259   uint32_t zbytes;
 260   uint32_t startrange, endrange;
 261   uint32_t gzdatasize, gzwhere;
 262   uint32_t orig_crc, offset;
 263   uint32_t target = 0;
 264   int i, okmem;
 265
 266   /* Is it a gzip image? */
 267   if (check_zip ((void *)where, size, &zbytes, &gzdatasize,
 268                  &orig_crc, &offset) == 0) {
 269
 270     if (offset + zbytes > size) {
 271       /* Assertion failure; check_zip is supposed to guarantee this
 272          never happens. */
 273       puts("internal error: check_zip returned nonsense\n");
 274       die();
 275     }
 276
 277     /* Find a good place to put it: search memory ranges in descending order
 278        until we find one that is legal and fits */
 279     okmem = 0;
 280     for ( i = nranges-1 ; i >= 0 ; i-- ) {
 281       /* We can't use > 4G memory (32 bits only.)  Truncate to 2^32-1
 282          so we don't have to deal with funny wraparound issues. */
 283
 284       /* Must be memory */
 285       if ( ranges[i].type != 1 )
 286         continue;
 287
 288       /* Range start */
 289       if ( ranges[i].start >= 0xFFFFFFFF )
 290         continue;
 291       startrange = (uint32_t)ranges[i].start;
 292
 293       /* Range end (0 for end means 2^64) */
 294       endrange = ((ranges[i+1].start >= 0xFFFFFFFF ||
 295                    ranges[i+1].start == 0)
 296                   ? 0xFFFFFFFF : (uint32_t)ranges[i+1].start);
 297
 298       /* Make sure we don't overwrite ourselves */
 299       if ( startrange < (uint32_t)&_end )
 300         startrange = (uint32_t)&_end;
 301
 302       /* Allow for alignment */
 303       startrange = (ranges[i].start + (UNZIP_ALIGN-1)) & ~(UNZIP_ALIGN-1);
 304
 305       /* In case we just killed the whole range... */
 306       if ( startrange >= endrange )
 307         continue;
 308
 309       /* Must be large enough... don't rely on gzwhere for this (wraparound) */
 310       if ( endrange-startrange < gzdatasize )
 311         continue;
 312
 313       /* This is where the gz image should be put if we put it in this range */
 314       gzwhere = (endrange - gzdatasize) & ~(UNZIP_ALIGN-1);
 315
 316       /* Cast to uint64_t just in case we're flush with the top byte */
 317       if ( (uint64_t)where+size >= gzwhere && where < endrange ) {
 318         /* Need to move source data to avoid compressed/uncompressed overlap */
 319         uint32_t newwhere;
 320
 321         if ( gzwhere-startrange < size )
 322           continue;             /* Can't fit both old and new */
 323
 324         newwhere = (gzwhere - size) & ~(UNZIP_ALIGN-1);
 325         printf("Moving compressed data from 0x%08x to 0x%08x\n",
 326                where, newwhere);
 327
 328         /* Our memcpy() is OK, because we always move from a higher
 329            address to a lower one */
 330         memcpy((void *)newwhere, (void *)where, size);
 331         where = newwhere;
 332       }
 333
 334       target = gzwhere;
 335       okmem = 1;
 336       break;
 337     }
 338
 339     if ( !okmem ) {
 340       printf("Not enough memory to decompress image (need 0x%08x bytes)\n",
 341              gzdatasize);
 342       die();
 343     }
 344
 345     printf("gzip image: decompressed addr 0x%08x, len 0x%08x: ",
 346            target, gzdatasize);
 347
 348     *size_p  = gzdatasize;
 349     *where_p = (uint32_t)unzip((void *)(where + offset), zbytes,
 350                                gzdatasize, orig_crc, (void *)target);
 351   }
 352 }
 353
 354 /*
 355  * Figure out the "geometry" of the disk in question
 356  */
 357 struct geometry {
 358   uint32_t sectors;             /* 512-byte sector count */
 359   uint32_t c, h, s;             /* C/H/S geometry */
 360   uint32_t offset;              /* Byte offset for disk */
 361   uint8_t type;                 /* Type byte for INT 13h AH=08h */
 362   uint8_t driveno;              /* Drive no */
 363 };
 364
 365 static const struct geometry geometries[] =
 366 {
 367   {  360*2, 40,  2,  9, 0, 0x01, 0 }, /*  360 K */
 368   {  720*2, 80,  2,  9, 0, 0x03, 0 }, /*  720 K*/
 369   { 1200*2, 80,  2, 15, 0, 0x02, 0 }, /* 1200 K */
 370   { 1440*2, 80,  2, 18, 0, 0x04, 0 }, /* 1440 K */
 371   { 1680*2, 80,  2, 21, 0, 0x04, 0 }, /* 1680 K */
 372   { 1722*2, 82,  2, 21, 0, 0x04, 0 }, /* 1722 K */
 373   { 2880*2, 80,  2, 36, 0, 0x06, 0 }, /* 2880 K */
 374   { 3840*2, 80,  2, 48, 0, 0x06, 0 }, /* 3840 K */
 375 };
 376 #define known_geometries (sizeof(geometries)/sizeof(struct geometry))
 377
 378 /* Format of a DOS partition table entry */
 379 struct ptab_entry {
 380   uint8_t active;
 381   uint8_t start_h, start_s, start_c;
 382   uint8_t type;
 383   uint8_t end_h, end_s, end_c;
 384   uint32_t start;
 385   uint32_t size;
 386 };
 387
 388 /* Format of a DOSEMU header */
 389 struct dosemu_header {
 390   uint8_t magic[7];             /* DOSEMU\0 */
 391   uint32_t h;
 392   uint32_t s;
 393   uint32_t c;
 394   uint32_t offset;
 395   uint8_t pad[105];
 396 } __attribute__((packed));
 397
 398 #define FOUR(a,b,c,d) (((a) << 24)|((b) << 16)|((c) << 8)|(d))
 399
 400 const struct geometry *get_disk_image_geometry(uint32_t where, uint32_t size)
 401 {
 402   static struct geometry hd_geometry = { 0, 0, 0, 0, 0, 0, 0x80 };
 403   struct ptab_entry ptab[4];    /* Partition table buffer */
 404   struct dosemu_header dosemu;
 405   unsigned int sectors, v;
 406   unsigned int max_c, max_h, max_s;
 407   unsigned int c, h, s, offset;
 408   int i;
 409   int drive_specified;
 410   const char *p;
 411
 412   printf("command line: %s\n", shdr->cmdline);
 413
 414   offset = 0;
 415   if ( CMD_HASDATA(p = getcmditem("offset")) && (v = atou(p)) )
 416     offset = v;
 417
 418   sectors = (size-offset) >> 9;
 419   for ( i = 0 ; i < known_geometries ; i++ ) {
 420     if ( sectors == geometries[i].sectors ) {
 421       hd_geometry = geometries[i];
 422       break;
 423     }
 424   }
 425
 426   hd_geometry.sectors = sectors;
 427   hd_geometry.offset  = offset;
 428
 429   /* Do we have a DOSEMU header? */
 430   memcpy(&dosemu, (char *)where+hd_geometry.offset, sizeof dosemu);
 431   if ( !memcmp("DOSEMU", dosemu.magic, 7) ) {
 432     /* Always a hard disk unless overruled by command-line options */
 433     hd_geometry.driveno = 0x80;
 434     hd_geometry.type = 0;
 435     hd_geometry.c = dosemu.c;
 436     hd_geometry.h = dosemu.h;
 437     hd_geometry.s = dosemu.s;
 438     hd_geometry.offset += dosemu.offset;
 439     sectors = (size-hd_geometry.offset) >> 9;
 440   }
 441
 442   if ( CMD_HASDATA(p = getcmditem("c")) && (v = atou(p)) )
 443     hd_geometry.c = v;
 444   if ( CMD_HASDATA(p = getcmditem("h")) && (v = atou(p)) )
 445     hd_geometry.h = v;
 446   if ( CMD_HASDATA(p = getcmditem("s")) && (v = atou(p)) )
 447     hd_geometry.s = v;
 448
 449   if ( (p = getcmditem("floppy")) != CMD_NOTFOUND ) {
 450     hd_geometry.driveno = CMD_HASDATA(p) ? atou(p) & 0x7f : 0;
 451     if ( hd_geometry.type == 0 )
 452       hd_geometry.type = 0x10;  /* ATAPI floppy, e.g. LS-120 */
 453     drive_specified = 1;
 454   } else if ( (p = getcmditem("harddisk")) != CMD_NOTFOUND ) {
 455     hd_geometry.driveno = CMD_HASDATA(p) ? atou(p) | 0x80 : 0x80;
 456     hd_geometry.type = 0;
 457     drive_specified = 1;
 458   }
 459
 460   if ( (hd_geometry.c == 0) || (hd_geometry.h == 0) ||
 461        (hd_geometry.s == 0) ) {
 462     /* Hard disk image, need to examine the partition table for geometry */
 463     memcpy(&ptab, (char *)where+hd_geometry.offset+(512-2-4*16), sizeof ptab);
 464
 465     max_c = max_h = 0;  max_s = 1;
 466     for ( i = 0 ; i < 4 ; i++ ) {
 467       if ( ptab[i].type ) {
 468         c = ptab[i].start_c + (ptab[i].start_s >> 6);
 469         s = (ptab[i].start_s & 0x3f);
 470         h = ptab[i].start_h;
 471
 472         if ( max_c < c ) max_c = c;
 473         if ( max_h < h ) max_h = h;
 474         if ( max_s < s ) max_s = s;
 475
 476         c = ptab[i].end_c + (ptab[i].end_s >> 6);
 477         s = (ptab[i].end_s & 0x3f);
 478         h = ptab[i].end_h;
 479
 480         if ( max_c < c ) max_c = c;
 481         if ( max_h < h ) max_h = h;
 482         if ( max_s < s ) max_s = s;
 483       }
 484     }
 485
 486     max_c++; max_h++;           /* Convert to count (1-based) */
 487
 488     if ( !hd_geometry.h )
 489       hd_geometry.h = max_h;
 490     if ( !hd_geometry.s )
 491       hd_geometry.s = max_s;
 492     if ( !hd_geometry.c )
 493       hd_geometry.c = sectors/(hd_geometry.h*hd_geometry.s);
 494   }
 495
 496   if ( (size-hd_geometry.offset) & 0x1ff ) {
 497     puts("MEMDISK: Image has fractional end sector\n");
 498   }
 499   if ( sectors % (hd_geometry.h*hd_geometry.s) ) {
 500     puts("MEMDISK: Image seems to have fractional end cylinder\n");
 501   }
 502   if ( (hd_geometry.c*hd_geometry.h*hd_geometry.s) > sectors ) {
 503     puts("MEMDISK: Image appears to be truncated\n");
 504   }
 505
 506   return &hd_geometry;
 507 }
 508
 509 /*
 510  * Jump here if all hope is gone...
 511  */
 512 void __attribute__((noreturn)) die(void)
 513 {
 514   asm volatile("sti");
 515   for(;;)
 516     asm volatile("hlt");
 517 }
 518
 519 /*
 520  * Find a $PnP installation check structure; return (ES << 16) + DI value
 521  */
 522 static uint32_t pnp_install_check(void)
 523 {
 524   uint32_t *seg;
 525   unsigned char *p, csum;
 526   int i, len;
 527
 528   for (seg = (uint32_t *)0xf0000; seg < (uint32_t *)0x100000; seg += 4) {
 529     if (*seg == ('$'+('P' << 8)+('n' << 16)+('P' << 24))) {
 530       p = (unsigned char *)seg;
 531       len = p[5];
 532       if (len < 0x21)
 533         continue;
 534       csum = 0;
 535       for (i = len; i; i--)
 536         csum += *p++;
 537       if (csum != 0)
 538         continue;
 539
 540       return (0xf000 << 16) + (uint16_t)(unsigned long)seg;
 541     }
 542   }
 543
 544   return 0;
 545 }
 546
 547 #define STACK_NEEDED    512     /* Number of bytes of stack */
 548
 549 /*
 550  * Actual setup routine
 551  * Returns the drive number (which is then passed in %dl to the
 552  * called routine.)
 553  */
 554 syscall_t syscall;
 555 void *sys_bounce;
 556
 557 void setup(syscall_t cs_syscall, void *cs_bounce)
 558 {
 559   unsigned int bin_size = (int) &_binary_memdisk_bin_size;
 560   struct memdisk_header *hptr;
 561   struct patch_area *pptr;
 562   uint16_t driverseg;
 563   uint32_t driverptr, driveraddr;
 564   uint16_t dosmem_k;
 565   uint32_t stddosmem;
 566   const struct geometry *geometry;
 567   int total_size, cmdlinelen;
 568   com32sys_t regs;
 569   uint32_t ramdisk_image, ramdisk_size;
 570   int bios_drives;
 571   int do_edd = -1;              /* -1 = default, 0 = no, 1 = yes */
 572
 573   /* Set up global variables */
 574   syscall = cs_syscall;
 575   sys_bounce = cs_bounce;
 576
 577   /* Show signs of life */
 578   printf("%s  %s\n", memdisk_version, copyright);
 579
 580   if ( !shdr->ramdisk_image || !shdr->ramdisk_size ) {
 581     puts("MEMDISK: No ramdisk image specified!\n");
 582     die();
 583   }
 584
 585   ramdisk_image = shdr->ramdisk_image;
 586   ramdisk_size  = shdr->ramdisk_size;
 587
 588   e820map_init();               /* Initialize memory data structure */
 589   get_mem();                    /* Query BIOS for memory map */
 590   parse_mem();                  /* Parse memory map */
 591
 592   printf("Ramdisk at 0x%08x, length 0x%08x\n",
 593          ramdisk_image, ramdisk_size);
 594
 595   unzip_if_needed(&ramdisk_image, &ramdisk_size);
 596
 597   geometry = get_disk_image_geometry(ramdisk_image, ramdisk_size);
 598
 599   if (getcmditem("edd") != CMD_NOTFOUND ||
 600       getcmditem("ebios") != CMD_NOTFOUND)
 601     do_edd = 1;
 602   else if (getcmditem("noedd") != CMD_NOTFOUND ||
 603            getcmditem("noebios") != CMD_NOTFOUND ||
 604            getcmditem("cbios") != CMD_NOTFOUND)
 605     do_edd = 0;
 606   else
 607     do_edd = (geometry->driveno & 0x80) ? 1 : 0;
 608
 609   printf("Disk is %s %d, %u K, C/H/S = %u/%u/%u, EDD %s\n",
 610          (geometry->driveno & 0x80) ? "hard disk" : "floppy",
 611          geometry->driveno & 0x7f,
 612          geometry->sectors >> 1,
 613          geometry->c, geometry->h, geometry->s,
 614          do_edd ? "on" : "off");
 615
 616   /* Reserve the ramdisk memory */
 617   insertrange(ramdisk_image, ramdisk_size, 2);
 618   parse_mem();                  /* Recompute variables */
 619
 620   /* Figure out where it needs to go */
 621   hptr = (struct memdisk_header *) &_binary_memdisk_bin_start;
 622   pptr = (struct patch_area *)(_binary_memdisk_bin_start + hptr->patch_offs);
 623
 624   dosmem_k = rdz_16(BIOS_BASEMEM);
 625   pptr->olddosmem = dosmem_k;
 626   stddosmem = dosmem_k << 10;
 627   /* If INT 15 E820 and INT 12 disagree, go with the most conservative */
 628   if ( stddosmem > dos_mem )
 629     stddosmem = dos_mem;
 630
 631   pptr->driveno   = geometry->driveno;
 632   pptr->drivetype = geometry->type;
 633   pptr->cylinders = geometry->c;
 634   pptr->heads     = geometry->h;
 635   pptr->sectors   = geometry->s;
 636   pptr->disksize  = geometry->sectors;
 637   pptr->diskbuf   = ramdisk_image + geometry->offset;
 638   pptr->statusptr = (geometry->driveno & 0x80) ? 0x474 : 0x441;
 639
 640   pptr->bootloaderid = shdr->type_of_loader;
 641
 642   pptr->configflags = 0;
 643   /* Set config flags */
 644   if ( getcmditem("ro") != CMD_NOTFOUND ) {
 645     puts("Marking disk readonly\n");
 646     pptr->configflags |= CONFIG_READONLY;
 647   }
 648   if ( getcmditem("raw") != CMD_NOTFOUND ) {
 649     puts("Using raw access to high memory\n");
 650     pptr->configflags &= ~CONFIG_SAFEINT|CONFIG_BIGRAW;
 651     pptr->configflags |= CONFIG_RAW;
 652   }
 653   if ( getcmditem("safeint") != CMD_NOTFOUND ) {
 654     puts("Using safe INT 15h access to high memory\n");
 655     pptr->configflags &= ~CONFIG_RAW|CONFIG_BIGRAW;
 656     pptr->configflags |= CONFIG_SAFEINT;
 657   }
 658   if ( getcmditem("bigraw") != CMD_NOTFOUND ) {
 659     puts("Using raw access to high memory - assuming big real mode\n");
 660     pptr->configflags &= ~CONFIG_SAFEINT;
 661     pptr->configflags |= CONFIG_BIGRAW|CONFIG_RAW;
 662   }
 663
 664   /* pptr->maxint13func defaults to EDD enabled, if compiled in */
 665   if (!do_edd)
 666     pptr->maxint13func = MAXINT13_NOEDD;
 667
 668   /* Set up a drive parameter table */
 669   if ( geometry->driveno & 0x80 ) {
 670     /* Hard disk */
 671     pptr->dpt.hd.max_cyl  = geometry->c-1;
 672     pptr->dpt.hd.max_head = geometry->h-1;
 673     pptr->dpt.hd.ctrl     = (geometry->h > 8) ? 0x08: 0;
 674   } else {
 675     /* Floppy - most of these fields are bogus and mimic
 676        a 1.44 MB floppy drive */
 677     pptr->dpt.fd.specify1 = 0xdf;
 678     pptr->dpt.fd.specify2 = 0x02;
 679     pptr->dpt.fd.delay    = 0x25;
 680     pptr->dpt.fd.sectors  = geometry->s;
 681     pptr->dpt.fd.bps      = 0x02;
 682     pptr->dpt.fd.isgap    = 0x12;
 683     pptr->dpt.fd.dlen     = 0xff;
 684     pptr->dpt.fd.fgap     = 0x6c;
 685     pptr->dpt.fd.ffill    = 0xf6;
 686     pptr->dpt.fd.settle   = 0x0f;
 687     pptr->dpt.fd.mstart   = 0x05;
 688
 689     pptr->dpt.fd.old_fd_dpt = rdz_32(BIOS_INT1E);
 690   }
 691
 692   /* Set up an EDD drive parameter table */
 693   pptr->edd_dpt.sectors = geometry->sectors;
 694   /* The EDD spec has this as <= 15482880  sectors (1024x240x63);
 695      this seems to make very little sense.  Try for something saner. */
 696   if (geometry->c <= 1024 && geometry->h <= 255 && geometry->s <= 63) {
 697     pptr->edd_dpt.c = geometry->c;
 698     pptr->edd_dpt.h = geometry->h;
 699     pptr->edd_dpt.s = geometry->s;
 700     pptr->edd_dpt.flags |= 0x0002; /* Geometry valid */
 701   }
 702   if (!(geometry->driveno & 0x80)) {
 703     /* Floppy drive.  Mark it as a removable device with
 704        media change notification; media is present. */
 705     pptr->edd_dpt.flags |= 0x0014;
 706   }
 707
 708   /* The size is given by hptr->total_size plus the size of the E820
 709      map -- 12 bytes per range; we may need as many as 2 additional
 710      ranges (each insertrange() can worst-case turn 1 area into 3)
 711      plus the terminating range, over what nranges currently show. */
 712   cmdlinelen = strlen(shdr->cmdline)+1;
 713   total_size  =  hptr->total_size;              /* Actual memdisk code */
 714   total_size += (nranges+3)*sizeof(ranges[0]);  /* E820 memory ranges */
 715   total_size += cmdlinelen;                     /* Command line */
 716   total_size += STACK_NEEDED;                   /* Stack */
 717   printf("Total size needed = %u bytes, allocating %uK\n",
 718          total_size, (total_size+0x3ff) >> 10);
 719
 720   if ( total_size > dos_mem ) {
 721     puts("MEMDISK: Insufficient low memory\n");
 722     die();
 723   }
 724
 725   driveraddr  = stddosmem - total_size;
 726   driveraddr &= ~0x3FF;
 727
 728   printf("Old dos memory at 0x%05x (map says 0x%05x), loading at 0x%05x\n",
 729          stddosmem, dos_mem, driveraddr);
 730
 731   /* Reserve this range of memory */
 732   wrz_16(BIOS_BASEMEM, driveraddr >> 10);
 733   insertrange(driveraddr, dos_mem-driveraddr, 2);
 734   parse_mem();
 735
 736   pptr->mem1mb     = low_mem  >> 10;
 737   pptr->mem16mb    = high_mem >> 16;
 738   if ( low_mem == (15 << 20) ) {
 739     /* lowmem maxed out */
 740     uint32_t int1588mem = (high_mem >> 10)+(low_mem >> 10);
 741     pptr->memint1588 = (int1588mem > 0xffff) ? 0xffff : int1588mem;
 742   } else {
 743     pptr->memint1588 = low_mem >> 10;
 744   }
 745
 746   printf("1588: 0x%04x  15E801: 0x%04x 0x%04x\n",
 747          pptr->memint1588, pptr->mem1mb, pptr->mem16mb);
 748
 749   driverseg = driveraddr >> 4;
 750   driverptr = driverseg  << 16;
 751
 752   /* Anything beyond the end is for the stack */
 753   pptr->mystack    = (uint16_t)(stddosmem-driveraddr);
 754
 755   pptr->oldint13 = rdz_32(BIOS_INT13);
 756   pptr->oldint15 = rdz_32(BIOS_INT15);
 757
 758   /* Adjust the E820 table: if there are null ranges (type 0)
 759      at the end, change them to type end of list (-1).
 760      This is necessary for the driver to be able to report end
 761      of list correctly. */
 762   while ( nranges && ranges[nranges-1].type == 0 ) {
 763     ranges[--nranges].type = -1;
 764   }
 765
 766   if (getcmditem("nopass") != CMD_NOTFOUND) {
 767     /* nopass specified - we're the only drive by definition */
 768     printf("nopass specified - we're the only drive\n");
 769     bios_drives = 0;
 770     pptr->drivecnt = 0;
 771     pptr->oldint13 = driverptr+hptr->iret_offs;
 772   } else {
 773     /* Query drive parameters of this type */
 774     memset(&regs, 0, sizeof regs);
 775     regs.es = 0;
 776     regs.eax.b[1] = 0x08;
 777     regs.edx.b[0] = geometry->driveno & 0x80;
 778     syscall(0x13, &regs, &regs);
 779
 780     if ( regs.eflags.l & 1 ) {
 781       printf("INT 13 08: Failure, assuming this is the only drive\n");
 782       pptr->drivecnt = 0;
 783     } else {
 784       printf("INT 13 08: Success, count = %u, BPT = %04x:%04x\n",
 785              regs.edx.b[0], regs.es, regs.edi.w[0]);
 786       pptr->drivecnt = regs.edx.b[0];
 787     }
 788
 789     /* Compare what INT 13h returned with the appropriate equipment byte */
 790     if ( geometry->driveno & 0x80 ) {
 791       bios_drives = rdz_8(BIOS_HD_COUNT);
 792     } else {
 793       uint8_t equip = rdz_8(BIOS_EQUIP);
 794
 795       if (equip & 1)
 796         bios_drives = (equip >> 6)+1;
 797       else
 798         bios_drives = 0;
 799     }
 800
 801     if (pptr->drivecnt > bios_drives) {
 802       printf("BIOS equipment byte says count = %d, go with that\n",
 803              bios_drives);
 804       pptr->drivecnt = bios_drives;
 805     }
 806   }
 807
 808   /* Add ourselves to the drive count */
 809   pptr->drivecnt++;
 810
 811   /* Discontiguous drive space.  There is no really good solution for this. */
 812   if ( pptr->drivecnt <= (geometry->driveno & 0x7f) )
 813     pptr->drivecnt = (geometry->driveno & 0x7f) + 1;
 814
 815   /* Pointer to the command line */
 816   pptr->cmdline_off = bin_size + (nranges+1)*sizeof(ranges[0]);
 817   pptr->cmdline_seg = driverseg;
 818
 819   /* Copy driver followed by E820 table followed by command line */
 820   {
 821     unsigned char *dpp = (unsigned char *)(driverseg << 4);
 822     dpp = memcpy_endptr(dpp, &_binary_memdisk_bin_start, bin_size);
 823     dpp = memcpy_endptr(dpp, ranges, (nranges+1)*sizeof(ranges[0]));
 824     dpp = memcpy_endptr(dpp, shdr->cmdline, cmdlinelen+1);
 825   }
 826
 827   /* Install the interrupt handlers */
 828   printf("old: int13 = %08x  int15 = %08x\n",
 829          rdz_32(BIOS_INT13), rdz_32(BIOS_INT15));
 830
 831   wrz_32(BIOS_INT13, driverptr+hptr->int13_offs);
 832   wrz_32(BIOS_INT15, driverptr+hptr->int15_offs);
 833
 834   printf("new: int13 = %08x  int15 = %08x\n",
 835          rdz_32(BIOS_INT13), rdz_32(BIOS_INT15));
 836
 837   /* Update various BIOS magic data areas (gotta love this shit) */
 838
 839   if ( geometry->driveno & 0x80 ) {
 840     /* Update BIOS hard disk count */
 841     uint8_t nhd = pptr->drivecnt;
 842
 843     if ( nhd > 128 )
 844       nhd = 128;
 845
 846     wrz_8(BIOS_HD_COUNT, nhd);
 847   } else {
 848     /* Update BIOS floppy disk count */
 849     uint8_t equip = rdz_8(BIOS_EQUIP);
 850     uint8_t nflop = pptr->drivecnt;
 851
 852     if ( nflop > 4 )            /* Limit of equipment byte */
 853       nflop = 4;
 854
 855     equip &= 0x3E;
 856     if ( nflop )
 857       equip |= ((nflop-1) << 6) | 0x01;
 858
 859     wrz_8(BIOS_EQUIP, equip);
 860   }
 861
 862   /* Reboot into the new "disk"; this is also a test for the interrupt hooks */
 863   puts("Loading boot sector... ");
 864
 865   memset(&regs, 0, sizeof regs);
 866   // regs.es = 0;
 867   regs.eax.w[0] = 0x0201;       /* Read sector */
 868   regs.ebx.w[0] = 0x7c00;       /* 0000:7C00 */
 869   regs.ecx.w[0] = 1;            /* One sector */
 870   regs.edx.w[0] = geometry->driveno;
 871   syscall(0x13, &regs, &regs);
 872
 873   if ( regs.eflags.l & 1 ) {
 874     puts("MEMDISK: Failed to load new boot sector\n");
 875     die();
 876   }
 877
 878   if ( getcmditem("pause") != CMD_NOTFOUND ) {
 879     puts("press any key to boot... ");
 880     regs.eax.w[0] = 0;
 881     syscall(0x16, &regs, NULL);
 882   }
 883
 884   puts("booting...\n");
 885
 886   /* On return the assembly code will jump to the boot vector */
 887   shdr->esdi = pnp_install_check();
 888   shdr->edx  = geometry->driveno;
 889 }