aboutsummaryrefslogtreecommitdiffstats
path: root/memdisk/setup.c
blob: 992db58fa1733e7537ebe101944f9aedd2d837fe (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2001-2009 H. Peter Anvin - All Rights Reserved
 *   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
 *   Portions copyright 2009-2010 Shao Miller
 *				  [El Torito code, mBFT, "safe hook"]
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

#include <stdint.h>
#include <minmax.h>
#include <suffix_number.h>
#include "bda.h"
#include "dskprobe.h"
#include "e820.h"
#include "conio.h"
#include "version.h"
#include "memdisk.h"
#include <version.h>

const char memdisk_version[] = "MEMDISK " VERSION_STR " " DATE;
const char copyright[] =
    "Copyright " FIRSTYEAR "-" YEAR_STR " H. Peter Anvin et al";

extern const char _binary_memdisk_chs_512_bin_start[];
extern const char _binary_memdisk_chs_512_bin_end[];
extern const char _binary_memdisk_chs_512_bin_size[];
extern const char _binary_memdisk_edd_512_bin_start[];
extern const char _binary_memdisk_edd_512_bin_end[];
extern const char _binary_memdisk_edd_512_bin_size[];
extern const char _binary_memdisk_iso_512_bin_start[];
extern const char _binary_memdisk_iso_512_bin_end[];
extern const char _binary_memdisk_iso_512_bin_size[];
extern const char _binary_memdisk_iso_2048_bin_start[];
extern const char _binary_memdisk_iso_2048_bin_end[];
extern const char _binary_memdisk_iso_2048_bin_size[];

/* Pull in structures common to MEMDISK and MDISKCHK.COM */
#include "mstructs.h"

/* An EDD disk packet */
struct edd_dsk_pkt {
    uint8_t size;		/* Packet size        */
    uint8_t res1;		/* Reserved           */
    uint16_t count;		/* Count to transfer  */
    uint32_t buf;		/* Buffer pointer     */
    uint64_t start;		/* LBA to start from  */
    uint64_t buf64;		/* 64-bit buf pointer */
} __attribute__ ((packed));

/* Change to 1 for El Torito debugging */
#define DBG_ELTORITO 0

#if DBG_ELTORITO
extern void eltorito_dump(uint32_t);
#endif

/*
 * Routine to seek for a command-line item and return a pointer
 * to the data portion, if present
 */

/* Magic return values */
#define CMD_NOTFOUND   ((char *)-1)	/* Not found */
#define CMD_BOOL       ((char *)-2)	/* Found boolean option */
#define CMD_HASDATA(X) ((int)(X) >= 0)

static const char *getcmditem(const char *what)
{
    const char *p;
    const char *wp = what;
    int match = 0;

    for (p = shdr->cmdline; *p; p++) {
	switch (match) {
	case 0:		/* Ground state */
	    if (*p == ' ')
		break;

	    wp = what;
	    match = 1;
	    /* Fall through */

	case 1:		/* Matching */
	    if (*wp == '\0') {
		if (*p == '=')
		    return p + 1;
		else if (*p == ' ')
		    return CMD_BOOL;
		else {
		    match = 2;
		    break;
		}
	    }
	    if (*p != *wp++)
		match = 2;
	    break;

	case 2:		/* Mismatch, skip rest of option */
	    if (*p == ' ')
		match = 0;	/* Next option */
	    break;
	}
    }

    /* Check for matching string at end of line */
    if (match == 1 && *wp == '\0')
	return CMD_BOOL;

    return CMD_NOTFOUND;
}

/*
 * Check to see if this is a gzip image
 */
#define UNZIP_ALIGN 512

extern const char _end[];		/* Symbol signalling end of data */

void unzip_if_needed(uint32_t * where_p, uint32_t * size_p)
{
    uint32_t where = *where_p;
    uint32_t size = *size_p;
    uint32_t zbytes;
    uint32_t startrange, endrange;
    uint32_t gzdatasize, gzwhere;
    uint32_t orig_crc, offset;
    uint32_t target = 0;
    int i, okmem;

    /* Is it a gzip image? */
    if (check_zip((void *)where, size, &zbytes, &gzdatasize,
		  &orig_crc, &offset) == 0) {

	if (offset + zbytes > size) {
	    /*
	     * Assertion failure; check_zip is supposed to guarantee this
	     * never happens.
	     */
	    die("internal error: check_zip returned nonsense\n");
	}

	/*
	 * Find a good place to put it: search memory ranges in descending
	 * order until we find one that is legal and fits
	 */
	okmem = 0;
	for (i = nranges - 1; i >= 0; i--) {
	    /*
	     * We can't use > 4G memory (32 bits only.)  Truncate to 2^32-1
	     * so we don't have to deal with funny wraparound issues.
	     */

	    /* Must be memory */
	    if (ranges[i].type != 1)
		continue;

	    /* Range start */
	    if (ranges[i].start >= 0xFFFFFFFF)
		continue;

	    startrange = (uint32_t) ranges[i].start;

	    /* Range end (0 for end means 2^64) */
	    endrange = ((ranges[i + 1].start >= 0xFFFFFFFF ||
			 ranges[i + 1].start == 0)
			? 0xFFFFFFFF : (uint32_t) ranges[i + 1].start);

	    /* Make sure we don't overwrite ourselves */
	    if (startrange < (uint32_t) _end)
		startrange = (uint32_t) _end;

	    /* Allow for alignment */
	    startrange =
		(ranges[i].start + (UNZIP_ALIGN - 1)) & ~(UNZIP_ALIGN - 1);

	    /* In case we just killed the whole range... */
	    if (startrange >= endrange)
		continue;

	    /*
	     * Must be large enough... don't rely on gzwhere for this
	     * (wraparound)
	     */
	    if (endrange - startrange < gzdatasize)
		continue;

	    /*
	     * This is where the gz image would be put if we put it in this
	     * range...
	     */
	    gzwhere = (endrange - gzdatasize) & ~(UNZIP_ALIGN - 1);

	    /* Cast to uint64_t just in case we're flush with the top byte */
	    if ((uint64_t) where + size >= gzwhere && where < endrange) {
		/*
		 * Need to move source data to avoid compressed/uncompressed
		 * overlap
		 */
		uint32_t newwhere;

		if (gzwhere - startrange < size)
		    continue;	/* Can't fit both old and new */

		newwhere = (gzwhere - size) & ~(UNZIP_ALIGN - 1);
		printf("Moving compressed data from 0x%08x to 0x%08x\n",
		       where, newwhere);

		memmove((void *)newwhere, (void *)where, size);
		where = newwhere;
	    }

	    target = gzwhere;
	    okmem = 1;
	    break;
	}

	if (!okmem)
	    die("Not enough memory to decompress image (need 0x%08x bytes)\n",
		gzdatasize);

	printf("gzip image: decompressed addr 0x%08x, len 0x%08x: ",
	       target, gzdatasize);

	*size_p = gzdatasize;
	*where_p = (uint32_t) unzip((void *)(where + offset), zbytes,
				    gzdatasize, orig_crc, (void *)target);
    }
}

/*
 * Figure out the "geometry" of the disk in question
 */
struct geometry {
    uint32_t sectors;		/* Sector count */
    uint32_t c, h, s;		/* C/H/S geometry */
    uint32_t offset;		/* Byte offset for disk */
    uint32_t boot_lba;		/* LBA of bootstrap code */
    uint8_t type;		/* Type byte for INT 13h AH=08h */
    uint8_t driveno;		/* Drive no */
    uint8_t sector_shift;	/* Sector size as a power of 2 */
    const char *hsrc, *ssrc;	/* Origins of H and S geometries */
};

/* Format of a DOS partition table entry */
struct ptab_entry {
    uint8_t active;
    uint8_t start_h, start_s, start_c;
    uint8_t type;
    uint8_t end_h, end_s, end_c;
    uint32_t start;
    uint32_t size;
} __attribute__ ((packed));

/* Format of a FAT filesystem superblock */
struct fat_extra {
    uint8_t bs_drvnum;
    uint8_t bs_resv1;
    uint8_t bs_bootsig;
    uint32_t bs_volid;
    char bs_vollab[11];
    char bs_filsystype[8];
} __attribute__ ((packed));
struct fat_super {
    uint8_t bs_jmpboot[3];
    char bs_oemname[8];
    uint16_t bpb_bytspersec;
    uint8_t bpb_secperclus;
    uint16_t bpb_rsvdseccnt;
    uint8_t bpb_numfats;
    uint16_t bpb_rootentcnt;
    uint16_t bpb_totsec16;
    uint8_t bpb_media;
    uint16_t bpb_fatsz16;
    uint16_t bpb_secpertrk;
    uint16_t bpb_numheads;
    uint32_t bpb_hiddsec;
    uint32_t bpb_totsec32;
    union {
	struct {
	    struct fat_extra extra;
	} fat16;
	struct {
	    uint32_t bpb_fatsz32;
	    uint16_t bpb_extflags;
	    uint16_t bpb_fsver;
	    uint32_t bpb_rootclus;
	    uint16_t bpb_fsinfo;
	    uint16_t bpb_bkbootsec;
	    char bpb_reserved[12];
	    /* Clever, eh?  Same fields, different offset... */
	    struct fat_extra extra;
	} fat32 __attribute__ ((packed));
    } x;
} __attribute__ ((packed));

/* Format of a DOSEMU header */
struct dosemu_header {
    uint8_t magic[7];		/* DOSEMU\0 */
    uint32_t h;
    uint32_t s;
    uint32_t c;
    uint32_t offset;
    uint8_t pad[105];
} __attribute__ ((packed));

#define FOUR(a,b,c,d) (((a) << 24)|((b) << 16)|((c) << 8)|(d))

static const struct geometry *get_disk_image_geometry(uint32_t where,
						      uint32_t size)
{
    static struct geometry hd_geometry;
    struct dosemu_header dosemu;
    unsigned int sectors, xsectors, v;
    unsigned int offset;
    int i;
    const char *p;

    printf("command line: %s\n", shdr->cmdline);

    hd_geometry.sector_shift = 9;	/* Assume floppy/HDD at first */

    offset = 0;
    if (CMD_HASDATA(p = getcmditem("offset")) && (v = atou(p)))
	offset = v;

    sectors = xsectors = (size - offset) >> hd_geometry.sector_shift;

    hd_geometry.hsrc = "guess";
    hd_geometry.ssrc = "guess";
    hd_geometry.sectors = sectors;
    hd_geometry.offset = offset;

    if ((p = getcmditem("iso")) != CMD_NOTFOUND) {
#if DBG_ELTORITO
	eltorito_dump(where);
#endif
	struct edd4_bvd *bvd = (struct edd4_bvd *)(where + 17 * 2048);
	/* Tiny sanity check */
	if ((bvd->boot_rec_ind != 0) || (bvd->ver != 1))
	    printf("El Torito BVD sanity check failed.\n");
	struct edd4_bootcat *boot_cat =
	    (struct edd4_bootcat *)(where + bvd->boot_cat * 2048);
	/* Another tiny sanity check */
	if ((boot_cat->validation_entry.platform_id != 0) ||
	    (boot_cat->validation_entry.key55 != 0x55) ||
	    (boot_cat->validation_entry.keyAA != 0xAA))
	    printf("El Torito boot catalog sanity check failed.\n");
	/* If we have an emulation mode, set the offset to the image */
	if (boot_cat->initial_entry.media_type)
	    hd_geometry.offset += boot_cat->initial_entry.load_block * 2048;
	else
	    /* We're a no-emulation mode, so we will boot to an offset */
	    hd_geometry.boot_lba = boot_cat->initial_entry.load_block * 4;
	if (boot_cat->initial_entry.media_type < 4) {
	    /* We're a floppy emulation mode or our params will be
	     * overwritten by the no emulation mode case
	     */
	    hd_geometry.driveno = 0x00;
	    hd_geometry.c = 80;
	    hd_geometry.h = 2;
	}
	switch (boot_cat->initial_entry.media_type) {
	case 0:		/* No emulation   */
	    hd_geometry.driveno = 0xE0;
	    hd_geometry.type = 10;	/* ATAPI removable media device */
	    hd_geometry.c = 65535;
	    hd_geometry.h = 255;
	    hd_geometry.s = 15;
	    /* 2048-byte sectors, so adjust the size and count */
	    hd_geometry.sector_shift = 11;
	    break;
	case 1:		/* 1.2 MB floppy  */
	    hd_geometry.s = 15;
	    hd_geometry.type = 2;
	    sectors = 2400;
	    break;
	case 2:		/* 1.44 MB floppy */
	    hd_geometry.s = 18;
	    hd_geometry.type = 4;
	    sectors = 2880;
	    break;
	case 3:		/* 2.88 MB floppy */
	    hd_geometry.s = 36;
	    hd_geometry.type = 6;
	    sectors = 5760;
	    break;
	case 4:
	    hd_geometry.driveno = 0x80;
	    hd_geometry.type = 0;
	    break;
	}
	sectors = (size - hd_geometry.offset) >> hd_geometry.sector_shift;

	/* For HDD emulation, we figure out the geometry later. Otherwise: */
	if (hd_geometry.s) {
	    hd_geometry.hsrc = hd_geometry.ssrc = "El Torito";
	}
	hd_geometry.sectors = sectors;
    }

    /* Do we have a DOSEMU header? */
    memcpy(&dosemu, (char *)where + hd_geometry.offset, sizeof dosemu);
    if (!memcmp("DOSEMU", dosemu.magic, 7)) {
	/* Always a hard disk unless overruled by command-line options */
	hd_geometry.driveno = 0x80;
	hd_geometry.type = 0;
	hd_geometry.c = dosemu.c;
	hd_geometry.h = dosemu.h;
	hd_geometry.s = dosemu.s;
	hd_geometry.offset += dosemu.offset;
	sectors = (size - hd_geometry.offset) >> hd_geometry.sector_shift;

	hd_geometry.hsrc = hd_geometry.ssrc = "DOSEMU";
    }

    if (CMD_HASDATA(p = getcmditem("c")) && (v = atou(p)))
	hd_geometry.c = v;
    if (CMD_HASDATA(p = getcmditem("h")) && (v = atou(p))) {
	hd_geometry.h = v;
	hd_geometry.hsrc = "cmd";
    }
    if (CMD_HASDATA(p = getcmditem("s")) && (v = atou(p))) {
	hd_geometry.s = v;
	hd_geometry.ssrc = "cmd";
    }

    if (!hd_geometry.h || !hd_geometry.s) {
	int h, s, max_h, max_s;

	max_h = hd_geometry.h;
	max_s = hd_geometry.s;

	if (!(max_h | max_s)) {
	    /* Look for a FAT superblock and if we find something that looks
	       enough like one, use geometry from that.  This takes care of
	       megafloppy images and unpartitioned hard disks. */
	    const struct fat_extra *extra = NULL;
	    const struct fat_super *fs = (const struct fat_super *)
		((char *)where + hd_geometry.offset);

	    if ((fs->bpb_media == 0xf0 || fs->bpb_media >= 0xf8) &&
		(fs->bs_jmpboot[0] == 0xe9 || fs->bs_jmpboot[0] == 0xeb) &&
		fs->bpb_bytspersec == 512 &&
		fs->bpb_numheads >= 1 && fs->bpb_numheads <= 256 &&
		fs->bpb_secpertrk >= 1 && fs->bpb_secpertrk <= 63) {
		extra =
		    fs->bpb_fatsz16 ? &fs->x.fat16.extra : &fs->x.fat32.extra;
		if (!
		    (extra->bs_bootsig == 0x29 && extra->bs_filsystype[0] == 'F'
		     && extra->bs_filsystype[1] == 'A'
		     && extra->bs_filsystype[2] == 'T'))
		    extra = NULL;
	    }
	    if (extra) {
		hd_geometry.driveno = extra->bs_drvnum & 0x80;
		max_h = fs->bpb_numheads;
		max_s = fs->bpb_secpertrk;
		hd_geometry.hsrc = hd_geometry.ssrc = "FAT";
	    }
	}

	if (!(max_h | max_s)) {
	    /* No FAT filesystem found to steal geometry from... */
	    if ((sectors < 4096 * 2) && (hd_geometry.sector_shift == 9)) {
		int ok = 0;
		unsigned int xsectors = sectors;

		hd_geometry.driveno = 0;	/* Assume floppy */

		while (!ok) {
		    /* Assume it's a floppy drive, guess a geometry */
		    unsigned int type, track;
		    int c, h, s = 0;

		    if (xsectors < 320 * 2) {
			c = 40;
			h = 1;
			type = 1;
		    } else if (xsectors < 640 * 2) {
			c = 40;
			h = 2;
			type = 1;
		    } else if (xsectors < 1200 * 2) {
			c = 80;
			h = 2;
			type = 3;
		    } else if (xsectors < 1440 * 2) {
			c = 80;
			h = 2;
			type = 2;
		    } else if (xsectors < 2880 * 2) {
			c = 80;
			h = 2;
			type = 4;
		    } else {
			c = 80;
			h = 2;
			type = 6;
		    }
		    track = c * h;
		    while (c < 256) {
			s = xsectors / track;
			if (s < 63 && (xsectors % track) == 0) {
			    ok = 1;
			    break;
			}
			c++;
			track += h;
		    }
		    if (ok) {
			max_h = h;
			max_s = s;
			hd_geometry.hsrc = hd_geometry.ssrc = "fd";
		    } else {
			/* No valid floppy geometry, fake it by simulating broken
			   sectors at the end of the image... */
			xsectors++;
		    }

		    hd_geometry.type = type;
		}
	    } else {
		/* Assume it is a hard disk image and scan for a partition table */
		const struct ptab_entry *ptab = (const struct ptab_entry *)
		    ((char *)where + hd_geometry.offset + (512 - 2 - 4 * 16));

		/* Assume hard disk */
		if (!hd_geometry.driveno)
		    hd_geometry.driveno = 0x80;

		if (*(uint16_t *) ((char *)where + hd_geometry.offset + 512 - 2) == 0xaa55) {
		    for (i = 0; i < 4; i++) {
			if (ptab[i].type && !(ptab[i].active & 0x7f)) {
			    s = (ptab[i].start_s & 0x3f);
			    h = ptab[i].start_h + 1;

			    if (max_h < h)
				max_h = h;
			    if (max_s < s)
				max_s = s;

			    s = (ptab[i].end_s & 0x3f);
			    h = ptab[i].end_h + 1;

			    if (max_h < h) {
				max_h = h;
				hd_geometry.hsrc = "MBR";
			    }
			    if (max_s < s) {
				max_s = s;
				hd_geometry.ssrc = "MBR";
			    }
			}
		    }
		}

		hd_geometry.type = 0;
	    }
	}

	if (!max_h)
	    max_h = xsectors > 2097152 ? 255 : 64;
	if (!max_s)
	    max_s = xsectors > 2097152 ? 63 : 32;

	hd_geometry.h    = max_h;
	hd_geometry.s    = max_s;
    }

    if (!hd_geometry.c)
	hd_geometry.c = xsectors / (hd_geometry.h * hd_geometry.s);

    if ((p = getcmditem("floppy")) != CMD_NOTFOUND) {
	hd_geometry.driveno = CMD_HASDATA(p) ? atou(p) & 0x7f : 0;
    } else if ((p = getcmditem("harddisk")) != CMD_NOTFOUND) {
	hd_geometry.driveno = CMD_HASDATA(p) ? atou(p) | 0x80 : 0x80;
    }

    if (hd_geometry.driveno & 0x80) {
	hd_geometry.type = 0;	/* Type = hard disk */
    } else {
	if (hd_geometry.type == 0)
	    hd_geometry.type = 0x10;	/* ATAPI floppy, e.g. LS-120 */
    }

    if ((size - hd_geometry.offset) & 0x1ff) {
	puts("MEMDISK: Image has fractional end sector\n");
    }
    if (sectors % (hd_geometry.h * hd_geometry.s)) {
	puts("MEMDISK: Image seems to have fractional end cylinder\n");
    }
    if ((hd_geometry.c * hd_geometry.h * hd_geometry.s) > sectors) {
	puts("MEMDISK: Image appears to be truncated\n");
    }

    return &hd_geometry;
}

/*
 * Find a $PnP installation check structure; return (ES << 16) + DI value
 */
static uint32_t pnp_install_check(void)
{
    uint32_t *seg;
    unsigned char *p, csum;
    int i, len;

    for (seg = (uint32_t *) 0xf0000; seg < (uint32_t *) 0x100000; seg += 4) {
	if (*seg == ('$' + ('P' << 8) + ('n' << 16) + ('P' << 24))) {
	    p = (unsigned char *)seg;
	    len = p[5];
	    if (len < 0x21)
		continue;
	    csum = 0;
	    for (i = len; i; i--)
		csum += *p++;
	    if (csum != 0)
		continue;

	    return (0xf000 << 16) + (uint16_t) (unsigned long)seg;
	}
    }

    return 0;
}

/*
 * Relocate the real-mode code to a new segment
 */
struct gdt_ptr {
    uint16_t limit;
    uint32_t base;
} __attribute__ ((packed));

static void set_seg_base(uint32_t gdt_base, int seg, uint32_t v)
{
    *(uint16_t *) (gdt_base + seg + 2) = v;
    *(uint8_t *) (gdt_base + seg + 4) = v >> 16;
    *(uint8_t *) (gdt_base + seg + 7) = v >> 24;
}

static void relocate_rm_code(uint32_t newbase)
{
    uint32_t gdt_base;
    uint32_t oldbase = rm_args.rm_base;
    uint32_t delta = newbase - oldbase;

    cli();
    memmove((void *)newbase, (void *)oldbase, rm_args.rm_size);

    rm_args.rm_return += delta;
    rm_args.rm_intcall += delta;
    rm_args.rm_bounce += delta;
    rm_args.rm_base += delta;
    rm_args.rm_gdt += delta;
    rm_args.rm_pmjmp += delta;
    rm_args.rm_rmjmp += delta;

    gdt_base = rm_args.rm_gdt;

    *(uint32_t *) (gdt_base + 2) = gdt_base;	/* GDT self-pointer */

    /* Segments 0x10 and 0x18 are real-mode-based */
    set_seg_base(gdt_base, 0x10, rm_args.rm_base);
    set_seg_base(gdt_base, 0x18, rm_args.rm_base);

#if __SIZEOF_POINTER__ == 4
    asm volatile ("lgdtl %0"::"m" (*(char *)gdt_base));
#elif __SIZEOF_POINTER__ == 8
    asm volatile ("lgdt %0"::"m" (*(char *)gdt_base));
#else
#error "unsupported architecture"
#endif

    *(uint32_t *) rm_args.rm_pmjmp += delta;
    *(uint16_t *) rm_args.rm_rmjmp += delta >> 4;

    rm_args.rm_handle_interrupt += delta;

    sti();
}

static uint8_t checksum_buf(const void *buf, int count)
{
    const uint8_t *p = buf;
    uint8_t c = 0;

    while (count--)
	c += *p++;

    return c;
}

static int stack_needed(void)
{
  const unsigned int min_stack = 128;	/* Minimum stack size */
  const unsigned int def_stack = 512;	/* Default stack size */
  unsigned int v = 0;
  const char *p;

  if (CMD_HASDATA(p = getcmditem("stack")))
    v = atou(p);

  if (!v)
    v = def_stack;

  if (v < min_stack)
    v = min_stack;

  return v;
}

/*
 * Set max memory by reservation
 * Adds reservations to data in INT15h to prevent access to the top of RAM
 * if there's any above the point specified.
 */
void setmaxmem(unsigned long long restop_ull)
{
    uint32_t restop;
    struct e820range *ep;
    const int int15restype = 2;

    /* insertrange() works on uint32_t */
    restop = min(restop_ull, UINT32_MAX);
    /* printf("  setmaxmem  '%08x%08x'  => %08x\n",
	(unsigned int)(restop_ull>>32), (unsigned int)restop_ull, restop); */

    for (ep = ranges; ep->type != -1U; ep++) {
	if (ep->type == 1) {	/* Only if available */
	    if (ep->start >= restop) {
		/* printf("  %08x -> 2\n", ep->start); */
		ep->type = int15restype;
	    } else if (ep[1].start > restop) {
		/* printf("  +%08x =2; cut %08x\n", restop, ep->start); */
		insertrange(restop, (ep[1].start - restop), int15restype);
	    }
	}
    }
    parse_mem();
}

struct real_mode_args rm_args;

/*
 * Actual setup routine
 * Returns the drive number (which is then passed in %dl to the
 * called routine.)
 */
void setup(const struct real_mode_args *rm_args_ptr)
{
    unsigned int bin_size;
    char *memdisk_hook;
    struct memdisk_header *hptr;
    struct patch_area *pptr;
    struct mBFT *mbft;
    uint16_t driverseg;
    uint32_t driverptr, driveraddr;
    uint16_t dosmem_k;
    uint32_t stddosmem;
    const struct geometry *geometry;
    unsigned int total_size;
    unsigned int cmdline_len, stack_len, e820_len;
    const struct edd4_bvd *bvd;
    const struct edd4_bootcat *boot_cat = 0;
    com32sys_t regs;
    uint32_t ramdisk_image, ramdisk_size;
    uint32_t boot_base, rm_base;
    int bios_drives;
    int do_edd = 1;		/* 0 = no, 1 = yes, default is yes */
    int do_eltorito = 0;	/* default is no */
    int no_bpt;			/* No valid BPT presented */
    uint32_t boot_seg = 0;	/* Meaning 0000:7C00 */
    uint32_t boot_len = 512;	/* One sector */
    const char *p;

    /* We need to copy the rm_args into their proper place */
    memcpy(&rm_args, rm_args_ptr, sizeof rm_args);
    sti();			/* ... then interrupts are safe */

    /* Show signs of life */
    printf("%s  %s\n", memdisk_version, copyright);

    if (!shdr->ramdisk_image || !shdr->ramdisk_size)
	die("MEMDISK: No ramdisk image specified!\n");

    ramdisk_image = shdr->ramdisk_image;
    ramdisk_size = shdr->ramdisk_size;

    e820map_init();		/* Initialize memory data structure */
    get_mem();			/* Query BIOS for memory map */
    parse_mem();		/* Parse memory map */

    printf("Ramdisk at 0x%08x, length 0x%08x\n", ramdisk_image, ramdisk_size);

    unzip_if_needed(&ramdisk_image, &ramdisk_size);

    geometry = get_disk_image_geometry(ramdisk_image, ramdisk_size);

    if (getcmditem("edd") != CMD_NOTFOUND ||
	getcmditem("ebios") != CMD_NOTFOUND)
	do_edd = 1;
    else if (getcmditem("noedd") != CMD_NOTFOUND ||
	     getcmditem("noebios") != CMD_NOTFOUND ||
	     getcmditem("cbios") != CMD_NOTFOUND)
	do_edd = 0;
    else
	do_edd = (geometry->driveno & 0x80) ? 1 : 0;

    if (getcmditem("iso") != CMD_NOTFOUND) {
	do_eltorito = 1;
	do_edd = 1;		/* Mandatory */
    }

    /* Choose the appropriate installable memdisk hook */
    if (do_eltorito) {
	if (geometry->sector_shift == 11) {
	    bin_size = (int)&_binary_memdisk_iso_2048_bin_size;
	    memdisk_hook = (char *)&_binary_memdisk_iso_2048_bin_start;
	} else {
	    bin_size = (int)&_binary_memdisk_iso_512_bin_size;
	    memdisk_hook = (char *)&_binary_memdisk_iso_512_bin_start;
	}
    } else {
	if (do_edd) {
	    bin_size = (int)&_binary_memdisk_edd_512_bin_size;
	    memdisk_hook = (char *)&_binary_memdisk_edd_512_bin_start;
	} else {
	    bin_size = (int)&_binary_memdisk_chs_512_bin_size;
	    memdisk_hook = (char *)&_binary_memdisk_chs_512_bin_start;
	}
    }

    /* Reserve the ramdisk memory */
    insertrange(ramdisk_image, ramdisk_size, 2);
    parse_mem();		/* Recompute variables */

    /* Figure out where it needs to go */
    hptr = (struct memdisk_header *)memdisk_hook;
    pptr = (struct patch_area *)(memdisk_hook + hptr->patch_offs);

    dosmem_k = rdz_16(BIOS_BASEMEM);
    pptr->mdi.olddosmem = dosmem_k;
    stddosmem = dosmem_k << 10;
    /* If INT 15 E820 and INT 12 disagree, go with the most conservative */
    if (stddosmem > dos_mem)
	stddosmem = dos_mem;

    pptr->driveno = geometry->driveno;
    pptr->drivetype = geometry->type;
    pptr->cylinders = geometry->c;	/* Possible precision loss */
    pptr->heads = geometry->h;
    pptr->sectors = geometry->s;
    pptr->mdi.disksize = geometry->sectors;
    pptr->mdi.diskbuf = ramdisk_image + geometry->offset;
    pptr->mdi.sector_shift = geometry->sector_shift;
    pptr->statusptr = (geometry->driveno & 0x80) ? 0x474 : 0x441;

    pptr->mdi.bootloaderid = shdr->type_of_loader;

    pptr->configflags = CONFIG_SAFEINT;	/* Default */
    /* Set config flags */
    if (getcmditem("ro") != CMD_NOTFOUND) {
	pptr->configflags |= CONFIG_READONLY;
    }
    if (getcmditem("raw") != CMD_NOTFOUND) {
	pptr->configflags &= ~CONFIG_MODEMASK;
	pptr->configflags |= CONFIG_RAW;
    }
    if (getcmditem("bigraw") != CMD_NOTFOUND) {
	pptr->configflags &= ~CONFIG_MODEMASK;
	pptr->configflags |= CONFIG_BIGRAW | CONFIG_RAW;
    }
    if (getcmditem("int") != CMD_NOTFOUND) {
	pptr->configflags &= ~CONFIG_MODEMASK;
	/* pptr->configflags |= 0; */
    }
    if (getcmditem("safeint") != CMD_NOTFOUND) {
	pptr->configflags &= ~CONFIG_MODEMASK;
	pptr->configflags |= CONFIG_SAFEINT;
    }

    printf("Disk is %s%d, %u%s K, C/H/S = %u/%u/%u (%s/%s), EDD %s, %s\n",
	   (geometry->driveno & 0x80) ? "hd" : "fd",
	   geometry->driveno & 0x7f,
	   geometry->sectors >> 1,
	   (geometry->sectors & 1) ? ".5" : "",
	   geometry->c, geometry->h, geometry->s,
	   geometry->hsrc, geometry->ssrc,
	   do_edd ? "on" : "off",
	   pptr->configflags & CONFIG_READONLY ? "ro" : "rw");

    puts("Using ");
    switch (pptr->configflags & CONFIG_MODEMASK) {
    case 0:
	puts("standard INT 15h");
	break;
    case CONFIG_SAFEINT:
	puts("safe INT 15h");
	break;
    case CONFIG_RAW:
	puts("raw");
	break;
    case CONFIG_RAW | CONFIG_BIGRAW:
	puts("big real mode raw");
	break;
    default:
	printf("unknown %#x", pptr->configflags & CONFIG_MODEMASK);
	break;
    }
    puts(" access to high memory\n");

    /* Set up a drive parameter table */
    if (geometry->driveno & 0x80) {
	/* Hard disk */
	pptr->dpt.hd.max_cyl = geometry->c - 1;
	pptr->dpt.hd.max_head = geometry->h - 1;
	pptr->dpt.hd.ctrl = (geometry->h > 8) ? 0x08 : 0;
    } else {
	/* Floppy - most of these fields are bogus and mimic
	   a 1.44 MB floppy drive */
	pptr->dpt.fd.specify1 = 0xdf;
	pptr->dpt.fd.specify2 = 0x02;
	pptr->dpt.fd.delay = 0x25;
	pptr->dpt.fd.sectors = geometry->s;
	pptr->dpt.fd.bps = 0x02;
	pptr->dpt.fd.isgap = 0x12;
	pptr->dpt.fd.dlen = 0xff;
	pptr->dpt.fd.fgap = 0x6c;
	pptr->dpt.fd.ffill = 0xf6;
	pptr->dpt.fd.settle = 0x0f;
	pptr->dpt.fd.mstart = 0x05;
	pptr->dpt.fd.maxtrack = geometry->c - 1;
	pptr->dpt.fd.cmos = geometry->type > 5 ? 5 : geometry->type;

	pptr->dpt.fd.old_fd_dpt = rdz_32(BIOS_INT1E);
    }

    /* Set up an EDD drive parameter table */
    if (do_edd) {
	pptr->edd_dpt.sectors = geometry->sectors;
	/* The EDD spec has this as <= 15482880  sectors (1024x240x63);
	   this seems to make very little sense.  Try for something saner. */
	if (geometry->c <= 1024 && geometry->h <= 255 && geometry->s <= 63) {
	    pptr->edd_dpt.c = geometry->c;
	    pptr->edd_dpt.h = geometry->h;
	    pptr->edd_dpt.s = geometry->s;
	    /* EDD-4 states that invalid geometry should be returned
	     * for INT 0x13, AH=0x48 "EDD Get Disk Parameters" call on an
	     * El Torito ODD.  Check for 2048-byte sector size
	     */
	    if (geometry->sector_shift != 11)
		pptr->edd_dpt.flags |= 0x0002;	/* Geometry valid */
	}
	if (!(geometry->driveno & 0x80)) {
	    /* Floppy drive.  Mark it as a removable device with
	       media change notification; media is present. */
	    pptr->edd_dpt.flags |= 0x0014;
	}

	pptr->edd_dpt.devpath[0] = pptr->mdi.diskbuf;
	pptr->edd_dpt.chksum = -checksum_buf(&pptr->edd_dpt.dpikey, 73 - 30);
    }

    if (do_eltorito) {
	bvd = (struct edd4_bvd *)(ramdisk_image + 17 * 2048);
	boot_cat =
	    (struct edd4_bootcat *)(ramdisk_image + bvd->boot_cat * 2048);
	pptr->cd_pkt.type = boot_cat->initial_entry.media_type;	/* Cheat */
	pptr->cd_pkt.driveno = geometry->driveno;
	pptr->cd_pkt.start = boot_cat->initial_entry.load_block;
	boot_seg = pptr->cd_pkt.load_seg = boot_cat->initial_entry.load_seg;
	pptr->cd_pkt.sect_count = boot_cat->initial_entry.sect_count;
	boot_len = pptr->cd_pkt.sect_count * 512;
	pptr->cd_pkt.geom1 = (uint8_t)(pptr->cylinders) & 0xFF;
	pptr->cd_pkt.geom2 =
	    (uint8_t)(pptr->sectors) | (uint8_t)((pptr->cylinders >> 2) & 0xC0);
	pptr->cd_pkt.geom3 = (uint8_t)(pptr->heads);
    }

    if ((p = getcmditem("mem")) != CMD_NOTFOUND) {
	setmaxmem(suffix_number(p));
    }

    /* The size is given by hptr->total_size plus the size of the E820
       map -- 12 bytes per range; we may need as many as 2 additional
       ranges (each insertrange() can worst-case turn 1 area into 3)
       plus the terminating range, over what nranges currently show. */
    total_size = hptr->total_size;	/* Actual memdisk code */
    e820_len = (nranges + 3) * sizeof(ranges[0]);
    total_size += e820_len;		/* E820 memory ranges */
    cmdline_len = strlen(shdr->cmdline) + 1;
    total_size += cmdline_len;		/* Command line */
    stack_len = stack_needed();
    total_size += stack_len;		/* Stack */
    printf("Code %u, meminfo %u, cmdline %u, stack %u\n",
	   hptr->total_size, e820_len, cmdline_len, stack_len);
    printf("Total size needed = %u bytes, allocating %uK\n",
	   total_size, (total_size + 0x3ff) >> 10);

    if (total_size > dos_mem)
	die("MEMDISK: Insufficient low memory\n");

    driveraddr = stddosmem - total_size;
    driveraddr &= ~0x3FF;

    printf("Old dos memory at 0x%05x (map says 0x%05x), loading at 0x%05x\n",
	   stddosmem, dos_mem, driveraddr);

    /* Reserve this range of memory */
    wrz_16(BIOS_BASEMEM, driveraddr >> 10);
    insertrange(driveraddr, dos_mem - driveraddr, 2);
    parse_mem();

    pptr->mem1mb = low_mem >> 10;
    pptr->mem16mb = high_mem >> 16;
    if (low_mem == (15 << 20)) {
	/* lowmem maxed out */
	uint32_t int1588mem = (high_mem >> 10) + (low_mem >> 10);
	pptr->memint1588 = (int1588mem > 0xffff) ? 0xffff : int1588mem;
    } else {
	pptr->memint1588 = low_mem >> 10;
    }

    printf("1588: 0x%04x  15E801: 0x%04x 0x%04x\n",
	   pptr->memint1588, pptr->mem1mb, pptr->mem16mb);

    driverseg = driveraddr >> 4;
    driverptr = driverseg << 16;

    /* Anything beyond the end is for the stack */
    pptr->mystack = (uint16_t) (stddosmem - driveraddr);

    pptr->mdi.oldint13.uint32 = rdz_32(BIOS_INT13);
    pptr->mdi.oldint15.uint32 = rdz_32(BIOS_INT15);

    /* Adjust the E820 table: if there are null ranges (type 0)
       at the end, change them to type end of list (-1).
       This is necessary for the driver to be able to report end
       of list correctly. */
    while (nranges && ranges[nranges - 1].type == 0) {
	ranges[--nranges].type = -1;
    }

    if (getcmditem("nopassany") != CMD_NOTFOUND) {
	printf("nopassany specified - we're the only drive of any kind\n");
	bios_drives = 0;
	pptr->drivecnt = 0;
	no_bpt = 1;
	pptr->mdi.oldint13.uint32 = driverptr + hptr->iret_offs;
	wrz_8(BIOS_EQUIP, rdz_8(BIOS_EQUIP) & ~0xc1);
	wrz_8(BIOS_HD_COUNT, 0);
    } else if (getcmditem("nopass") != CMD_NOTFOUND) {
	printf("nopass specified - we're the only drive\n");
	bios_drives = 0;
	pptr->drivecnt = 0;
	no_bpt = 1;
    } else {
	/* Query drive parameters of this type */
	memset(&regs, 0, sizeof regs);
	regs.es = 0;
	regs.eax.b[1] = 0x08;
	regs.edx.b[0] = geometry->driveno & 0x80;
	intcall(0x13, &regs, &regs);

	/* Note: per suggestion from the Interrupt List, consider
	   INT 13 08 to have failed if the sector count in CL is zero. */
	if ((regs.eflags.l & 1) || !(regs.ecx.b[0] & 0x3f)) {
	    printf("INT 13 08: Failure, assuming this is the only drive\n");
	    pptr->drivecnt = 0;
	    no_bpt = 1;
	} else {
	    printf("INT 13 08: Success, count = %u, BPT = %04x:%04x\n",
		   regs.edx.b[0], regs.es, regs.edi.w[0]);
	    pptr->drivecnt = regs.edx.b[0];
	    no_bpt = !(regs.es | regs.edi.w[0]);
	}

	/* Compare what INT 13h returned with the appropriate equipment byte */
	if (geometry->driveno & 0x80) {
	    bios_drives = rdz_8(BIOS_HD_COUNT);
	} else {
	    uint8_t equip = rdz_8(BIOS_EQUIP);

	    if (equip & 1)
		bios_drives = (equip >> 6) + 1;
	    else
		bios_drives = 0;
	}

	if (pptr->drivecnt > bios_drives) {
	    printf("BIOS equipment byte says count = %d, go with that\n",
		   bios_drives);
	    pptr->drivecnt = bios_drives;
	}
    }

    /* Add ourselves to the drive count */
    pptr->drivecnt++;

    /* Discontiguous drive space.  There is no really good solution for this. */
    if (pptr->drivecnt <= (geometry->driveno & 0x7f))
	pptr->drivecnt = (geometry->driveno & 0x7f) + 1;

    /* Probe for contiguous range of BIOS drives starting with driveno */
    pptr->driveshiftlimit = probe_drive_range(geometry->driveno) + 1;
    if ((pptr->driveshiftlimit & 0x80) != (geometry->driveno & 0x80))
	printf("We lost the last drive in our class of drives.\n");
    printf("Drive probing gives drive shift limit: 0x%02x\n",
	pptr->driveshiftlimit);

    /* Pointer to the command line */
    pptr->mdi.cmdline.seg_off.offset = bin_size + (nranges + 1) * sizeof(ranges[0]);
    pptr->mdi.cmdline.seg_off.segment = driverseg;

    /* Copy driver followed by E820 table followed by command line */
    {
	unsigned char *dpp = (unsigned char *)(driverseg << 4);

	/* Adjust these pointers to point to the installed image */
	/* Careful about the order here... the image isn't copied yet! */
	pptr = (struct patch_area *)(dpp + hptr->patch_offs);
	hptr = (struct memdisk_header *)dpp;

	/* Actually copy to low memory */
	dpp = mempcpy(dpp, memdisk_hook, bin_size);
	dpp = mempcpy(dpp, ranges, (nranges + 1) * sizeof(ranges[0]));
	dpp = mempcpy(dpp, shdr->cmdline, cmdline_len);
    }

    /* Note the previous INT 13h hook in the "safe hook" structure */
    hptr->safe_hook.old_hook.uint32 = pptr->mdi.oldint13.uint32;

    /* Re-fill the "safe hook" mBFT field with the physical address */
    mbft = (struct mBFT *)(((const char *)hptr) + hptr->safe_hook.mbft);
    hptr->safe_hook.mbft = (size_t)mbft;

    /* Update various BIOS magic data areas (gotta love this shit) */

    if (geometry->driveno & 0x80) {
	/* Update BIOS hard disk count */
	uint8_t nhd = pptr->drivecnt;

	if (nhd > 128)
	    nhd = 128;

	if (!do_eltorito)
	    wrz_8(BIOS_HD_COUNT, nhd);
    } else {
	/* Update BIOS floppy disk count */
	uint8_t equip = rdz_8(BIOS_EQUIP);
	uint8_t nflop = pptr->drivecnt;

	if (nflop > 4)		/* Limit of equipment byte */
	    nflop = 4;

	equip &= 0x3E;
	if (nflop)
	    equip |= ((nflop - 1) << 6) | 0x01;

	wrz_8(BIOS_EQUIP, equip);

	/* Install DPT pointer if this was the only floppy */
	if (getcmditem("dpt") != CMD_NOTFOUND ||
	    ((nflop == 1 || no_bpt) && getcmditem("nodpt") == CMD_NOTFOUND)) {
	    /* Do install a replacement DPT into INT 1Eh */
	    pptr->mdi.dpt_ptr =
		hptr->patch_offs + offsetof(struct patch_area, dpt);
	}
    }

    /* Complete the mBFT */
    mbft->acpi.signature[0] = 'm';	/* "mBFT" */
    mbft->acpi.signature[1] = 'B';
    mbft->acpi.signature[2] = 'F';
    mbft->acpi.signature[3] = 'T';
    mbft->safe_hook = (size_t)&hptr->safe_hook;
    mbft->acpi.checksum = -checksum_buf(mbft, mbft->acpi.length);

    /* Install the interrupt handlers */
    printf("old: int13 = %08x  int15 = %08x  int1e = %08x\n",
	   rdz_32(BIOS_INT13), rdz_32(BIOS_INT15), rdz_32(BIOS_INT1E));

    wrz_32(BIOS_INT13, driverptr + hptr->int13_offs);
    wrz_32(BIOS_INT15, driverptr + hptr->int15_offs);
    if (pptr->mdi.dpt_ptr)
	wrz_32(BIOS_INT1E, driverptr + pptr->mdi.dpt_ptr);

    printf("new: int13 = %08x  int15 = %08x  int1e = %08x\n",
	   rdz_32(BIOS_INT13), rdz_32(BIOS_INT15), rdz_32(BIOS_INT1E));

    /* Figure out entry point */
    if (!boot_seg) {
	boot_base = 0x7c00;
	shdr->sssp = 0x7c00;
	shdr->csip = 0x7c00;
    } else {
	boot_base = boot_seg << 4;
	shdr->sssp = boot_seg << 16;
	shdr->csip = boot_seg << 16;
    }

    /* Relocate the real-mode code to below the stub */
    rm_base = (driveraddr - rm_args.rm_size) & ~15;
    if (rm_base < boot_base + boot_len)
	die("MEMDISK: bootstrap too large to load\n");

    relocate_rm_code(rm_base);

    /* Reboot into the new "disk" */
    puts("Loading boot sector... ");

    memcpy((void *)boot_base,
	   (char *)pptr->mdi.diskbuf + geometry->boot_lba * 512,
	   boot_len);

    if (getcmditem("pause") != CMD_NOTFOUND) {
	puts("press any key to boot... ");
	memset(&regs, 0, sizeof regs);
	regs.eax.w[0] = 0;
	intcall(0x16, &regs, NULL);
    }

    puts("booting...\n");

    /* On return the assembly code will jump to the boot vector */
    shdr->esdi = pnp_install_check();
    shdr->edx = geometry->driveno;
}