xref: /netbsd-src/sys/arch/atari/stand/installboot/installboot.c (revision b7b7574d3bf8eeb51a1fa3977b59142ec6434a55)
1 /*	$NetBSD: installboot.c,v 1.28 2014/03/31 06:32:31 ozaki-r Exp $	*/
2 
3 /*
4  * Copyright (c) 1995 Waldi Ravens
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *        This product includes software developed by Waldi Ravens.
18  * 4. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #include <sys/types.h>
34 #include <sys/param.h>
35 #include <sys/sysctl.h>
36 #include <sys/ioctl.h>
37 #include <unistd.h>
38 #include <string.h>
39 #include <stdlib.h>
40 #include <stdio.h>
41 #include <paths.h>
42 #include <fcntl.h>
43 #include <errno.h>
44 #include <err.h>
45 #include <limits.h>
46 #include <nlist.h>
47 #include <kvm.h>
48 
49 #define	DKTYPENAMES
50 #define	FSTYPENAMES
51 #include <sys/disklabel.h>
52 #include <machine/ahdilabel.h>
53 
54 #include "installboot.h"
55 
56 static void	usage(void);
57 static void	oscheck(void);
58 static u_int	abcksum(void *);
59 static void	setNVpref(void);
60 static void	setIDEpar(u_int8_t *, size_t);
61 static void	mkahdiboot(struct ahdi_root *, char *,
62 						char *, u_int32_t);
63 static void	mkbootblock(struct bootblock *, char *,
64 				char *, struct disklabel *, u_int);
65 static void	install_fd(char *, struct disklabel *);
66 static void	install_sd(char *, struct disklabel *);
67 static void	install_wd(char *, struct disklabel *);
68 
69 static struct bootblock	bootarea;
70 static struct ahdi_root ahdiboot;
71 static const char	mdecpath[] = PATH_MDEC;
72 static const char	stdpath[] = PATH_STD;
73 static const char	milanpath[] = PATH_MILAN;
74 static int		nowrite = 0;
75 static int		verbose = 0;
76 static int		trackpercyl = 0;
77 static int		secpertrack = 0;
78 static int		milan = 0;
79 
80 static void
81 usage(void)
82 {
83 	fprintf(stderr,
84 		"usage: installboot [options] device\n"
85 		"where options are:\n"
86 		"\t-N  do not actually write anything on the disk\n"
87 		"\t-m  use Milan boot blocks\n"
88 		"\t-t  number of tracks per cylinder (IDE disk)\n"
89 		"\t-u  number of sectors per track (IDE disk)\n"
90 		"\t-v  verbose mode\n");
91 	exit(EXIT_FAILURE);
92 }
93 
94 int
95 main(int argc, char *argv[])
96 {
97 	struct disklabel dl;
98 	char		 *dn;
99 	char		 *devchr;
100 	int		 fd, c;
101 
102 	/* check OS bootversion */
103 	oscheck();
104 
105 	/* parse options */
106 	while ((c = getopt(argc, argv, "Nmt:u:v")) != -1) {
107 		switch (c) {
108 		  case 'N':
109 			nowrite = 1;
110 			break;
111 		  case 'm':
112 			milan = 1;
113 			break;
114 		  case 't':
115 			trackpercyl = atoi(optarg);
116 			break;
117 		  case 'u':
118 			secpertrack = atoi(optarg);
119 			break;
120 		  case 'v':
121 			verbose = 1;
122 			break;
123 		  default:
124 			usage();
125 		}
126 	}
127 	argv += optind;
128 	argc -= optind;
129 	if (argc != 1)
130 		usage();
131 
132 	/* get disk label */
133 	size_t dnlen = sizeof(_PATH_DEV) + strlen(argv[0]) + 8;
134 	dn = alloca(dnlen);
135 	if (!strchr(argv[0], '/')) {
136 		snprintf(dn, dnlen, "%sr%s%c", _PATH_DEV, argv[0],
137 		    RAW_PART + 'a');
138 		fd = open(dn, O_RDONLY);
139 		if (fd < 0 && errno == ENOENT) {
140 			snprintf(dn, dnlen, "%sr%s", _PATH_DEV, argv[0]);
141 			fd = open(dn, O_RDONLY);
142 		}
143 	} else {
144 		snprintf(dn, dnlen, "%s", argv[0]);
145 		fd = open(dn, O_RDONLY);
146 	}
147 	if (fd < 0)
148 		err(EXIT_FAILURE, "%s", dn);
149 	if (ioctl(fd, DIOCGDINFO, &dl))
150 		err(EXIT_FAILURE, "%s: DIOCGDINFO", dn);
151 	if (close(fd))
152 		err(EXIT_FAILURE, "%s", dn);
153 
154 	/* Eg: in /dev/fd0c, set devchr to point to the 'f' */
155 	devchr = strrchr(dn, '/') + 1;
156 	if (*devchr == 'r')
157 		++devchr;
158 
159 	switch (*devchr) {
160 		case 'f': /* fd */
161 			install_fd(dn, &dl);
162 			break;
163 		case 'w': /* wd */
164 			install_wd(dn, &dl);
165 			setNVpref();
166 			break;
167 		case 's': /* sd */
168 			install_sd(dn, &dl);
169 			setNVpref();
170 			break;
171 		default:
172 			errx(EXIT_FAILURE,
173 			     "%s: '%c': Device type not supported.",
174 			     dn, *devchr);
175 	}
176 
177 	return(EXIT_SUCCESS);
178 }
179 
180 static void
181 oscheck(void)
182 {
183 	struct nlist kbv[] = {
184 		{ .n_name = "_bootversion" },
185 		{ .n_name = NULL }
186 	};
187 	kvm_t		*kd_kern;
188 	char		errbuf[_POSIX2_LINE_MAX];
189 	u_short		kvers;
190 	struct stat	sb;
191 
192 	if (stat(_PATH_UNIX, &sb) < 0) {
193 		warnx("Cannot stat %s, no bootversion check done", _PATH_UNIX);
194 		return;
195 	}
196 
197 	kd_kern = kvm_openfiles(NULL, NULL, NULL, O_RDONLY, errbuf);
198 	if (kd_kern == NULL)
199 		errx(EXIT_FAILURE, "kvm_openfiles: %s", errbuf);
200 	if (kvm_nlist(kd_kern, kbv) == -1)
201 		errx(EXIT_FAILURE, "kvm_nlist: %s", kvm_geterr(kd_kern));
202 	if (kbv[0].n_value == 0)
203 		errx(EXIT_FAILURE, "%s not in namelist", kbv[0].n_name);
204 	if (kvm_read(kd_kern, kbv[0].n_value, &kvers, sizeof(kvers)) == -1)
205 		errx(EXIT_FAILURE, "kvm_read: %s", kvm_geterr(kd_kern));
206 	kvm_close(kd_kern);
207 	if (kvers != BOOTVERSION)
208 		errx(EXIT_FAILURE, "Kern bootversion: %d, expected: %d",
209 		    kvers, BOOTVERSION);
210 }
211 
212 static void
213 install_fd(char *devnm, struct disklabel *label)
214 {
215 	const char	 *machpath;
216 	char		 *xxboot, *bootxx;
217 	struct partition *rootpart;
218 
219 	if (label->d_secsize != 512)
220 		errx(EXIT_FAILURE,
221 		     "%s: %u: Block size not supported.", devnm,
222 							  label->d_secsize);
223 	if (label->d_ntracks != 2)
224 		errx(EXIT_FAILURE,
225 		     "%s: Single sided floppy not supported.", devnm);
226 
227 	if (milan)
228 		machpath = milanpath;
229 	else
230 		machpath = stdpath;
231 	size_t xxbootlen = strlen(mdecpath) + strlen(machpath) + 8;
232 	xxboot = alloca(xxbootlen);
233 	snprintf(xxboot, xxbootlen, "%s%sfdboot", mdecpath, machpath);
234 	bootxx = alloca(xxbootlen);
235 	snprintf(bootxx, xxbootlen, "%s%sbootxx", mdecpath, machpath);
236 
237 	/* first used partition (a, b or c) */		/* XXX */
238 	for (rootpart = label->d_partitions; ; ++rootpart) {
239 		if (rootpart->p_size)
240 			break;
241 	}
242 	if (rootpart != label->d_partitions) {		/* XXX */
243 		*(label->d_partitions) = *rootpart;
244 		memset(rootpart, 0, sizeof(*rootpart));
245 	}
246 	label->d_partitions->p_fstype = FS_BSDFFS;	/* XXX */
247 	label->d_npartitions = 1;
248 	label->d_checksum = 0;
249 	label->d_checksum = dkcksum(label);
250 
251 	trackpercyl = secpertrack = 0;
252 	mkbootblock(&bootarea, xxboot, bootxx, label, 0);
253 
254 	if (!nowrite) {
255 		int	fd;
256 		if ((fd = open(devnm, O_WRONLY)) < 0)
257 			err(EXIT_FAILURE, "%s", devnm);
258 		if (write(fd, &bootarea, sizeof(bootarea)) != sizeof(bootarea))
259 			err(EXIT_FAILURE, "%s", devnm);
260 		if (close(fd))
261 			err(EXIT_FAILURE, "%s", devnm);
262 		if (verbose)
263 			printf("Boot block installed on %s\n", devnm);
264 	}
265 }
266 
267 static void
268 install_sd(char *devnm, struct disklabel *label)
269 {
270 	const char	 *machpath;
271 	char		 *xxb00t, *xxboot, *bootxx;
272 	struct disklabel rawlabel;
273 	u_int32_t	 bbsec;
274 	u_int		 magic;
275 
276 	if (label->d_partitions[0].p_size == 0)
277 		errx(EXIT_FAILURE, "%s: No root-filesystem.", devnm);
278 	if (label->d_partitions[0].p_fstype != FS_BSDFFS)
279 		errx(EXIT_FAILURE, "%s: %s: Illegal root-filesystem type.",
280 		     devnm, fstypenames[label->d_partitions[0].p_fstype]);
281 
282 	bbsec = readdisklabel(devnm, &rawlabel);
283 	if (bbsec == NO_BOOT_BLOCK)
284 		errx(EXIT_FAILURE, "%s: No NetBSD boot block.", devnm);
285 	if (memcmp(label, &rawlabel, sizeof(*label)))
286 		errx(EXIT_FAILURE, "%s: Invalid NetBSD boot block.", devnm);
287 
288 	if (milan)
289 		machpath = milanpath;
290 	else
291 		machpath = stdpath;
292 	if (bbsec) {
293 		size_t xxb00tlen = strlen(mdecpath) + strlen(machpath) + 14;
294 		xxb00t = alloca(xxb00tlen);
295 		snprintf(xxb00t, xxb00tlen, "%s%ssdb00t.ahdi", mdecpath, machpath);
296 		xxboot = alloca(xxb00tlen);
297 		snprintf(xxboot, xxb00tlen, "%s%sxxboot.ahdi", mdecpath, machpath);
298 		magic = AHDIMAGIC;
299 	} else {
300 		size_t xxbootlen = strlen(mdecpath) + strlen(machpath) + 8;
301 		xxb00t = NULL;
302 		xxboot = alloca(xxbootlen);
303 		snprintf(xxboot, xxbootlen, "%s%ssdboot", mdecpath, machpath);
304 		magic = NBDAMAGIC;
305 	}
306 	size_t bootxxlen = strlen(mdecpath) + strlen(machpath) + 8;
307 	bootxx = alloca(bootxxlen);
308 	snprintf(bootxx, bootxxlen, "%s%sbootxx", mdecpath, machpath);
309 
310 	trackpercyl = secpertrack = 0;
311 	if (xxb00t)
312 		mkahdiboot(&ahdiboot, xxb00t, devnm, bbsec);
313 	mkbootblock(&bootarea, xxboot, bootxx, label, magic);
314 
315 	if (!nowrite) {
316 		off_t	bbo = (off_t)bbsec * AHDI_BSIZE;
317 		int	fd;
318 
319 		if ((fd = open(devnm, O_WRONLY)) < 0)
320 			err(EXIT_FAILURE, "%s", devnm);
321 		if (lseek(fd, bbo, SEEK_SET) != bbo)
322 			err(EXIT_FAILURE, "%s", devnm);
323 		if (write(fd, &bootarea, sizeof(bootarea)) != sizeof(bootarea))
324 			err(EXIT_FAILURE, "%s", devnm);
325 		if (verbose)
326 			printf("Boot block installed on %s (sector %d)\n",
327 			    devnm, bbsec);
328 		if (xxb00t) {
329 			if (lseek(fd, (off_t)0, SEEK_SET) != 0)
330 				err(EXIT_FAILURE, "%s", devnm);
331 			if (write(fd, &ahdiboot, sizeof(ahdiboot)) !=
332 			    sizeof(ahdiboot))
333 				err(EXIT_FAILURE, "%s", devnm);
334 			if (verbose)
335 				printf("AHDI root  installed on %s (0)\n",
336 				    devnm);
337 		}
338 		if (close(fd))
339 			err(EXIT_FAILURE, "%s", devnm);
340 	}
341 }
342 
343 static void
344 install_wd(char *devnm, struct disklabel *label)
345 {
346 	const char	 *machpath;
347 	char		 *xxb00t, *xxboot, *bootxx;
348 	struct disklabel rawlabel;
349 	u_int32_t	 bbsec;
350 	u_int		 magic;
351 
352 	if (label->d_partitions[0].p_size == 0)
353 		errx(EXIT_FAILURE, "%s: No root-filesystem.", devnm);
354 	if (label->d_partitions[0].p_fstype != FS_BSDFFS)
355 		errx(EXIT_FAILURE, "%s: %s: Illegal root-filesystem type.",
356 		     devnm, fstypenames[label->d_partitions[0].p_fstype]);
357 
358 	bbsec = readdisklabel(devnm, &rawlabel);
359 	if (bbsec == NO_BOOT_BLOCK)
360 		errx(EXIT_FAILURE, "%s: No NetBSD boot block.", devnm);
361 	if (memcmp(label, &rawlabel, sizeof(*label)))
362 		errx(EXIT_FAILURE, "%s: Invalid NetBSD boot block.", devnm);
363 
364 	if (milan)
365 		machpath = milanpath;
366 	else
367 		machpath = stdpath;
368 	if (bbsec) {
369 		size_t xxb00tlen = strlen(mdecpath) + strlen(machpath) + 14;
370 		xxb00t = alloca(xxb00tlen);
371 		snprintf(xxb00t, xxb00tlen, "%s%swdb00t.ahdi", mdecpath, machpath);
372 		xxboot = alloca(xxb00tlen);
373 		snprintf(xxboot, xxb00tlen, "%s%sxxboot.ahdi", mdecpath, machpath);
374 		magic = AHDIMAGIC;
375 	} else {
376 		size_t xxbootlen = strlen(mdecpath) + strlen(machpath) + 8;
377 		xxb00t = NULL;
378 		xxboot = alloca(xxbootlen);
379 		snprintf(xxboot, xxbootlen, "%s%swdboot", mdecpath, machpath);
380 		magic = NBDAMAGIC;
381 	}
382 	size_t bootxxlen = strlen(mdecpath) + strlen(machpath) + 8;
383 	bootxx = alloca(bootxxlen);
384 	snprintf(bootxx, bootxxlen, "%s%sbootxx", mdecpath, machpath);
385 
386 	if (xxb00t)
387 		mkahdiboot(&ahdiboot, xxb00t, devnm, bbsec);
388 	mkbootblock(&bootarea, xxboot, bootxx, label, magic);
389 
390 	if (!nowrite) {
391 		int	fd;
392 		off_t	bbo;
393 
394 		bbo = (off_t)bbsec * AHDI_BSIZE;
395 		if ((fd = open(devnm, O_WRONLY)) < 0)
396 			err(EXIT_FAILURE, "%s", devnm);
397 		if (lseek(fd, bbo, SEEK_SET) != bbo)
398 			err(EXIT_FAILURE, "%s", devnm);
399 		if (write(fd, &bootarea, sizeof(bootarea)) != sizeof(bootarea))
400 			err(EXIT_FAILURE, "%s", devnm);
401 		if (verbose)
402 			printf("Boot block installed on %s (sector %d)\n",
403 			    devnm, bbsec);
404 		if (xxb00t) {
405 			if (lseek(fd, (off_t)0, SEEK_SET) != 0)
406 				err(EXIT_FAILURE, "%s", devnm);
407 			if (write(fd, &ahdiboot, sizeof(ahdiboot))
408 							!= sizeof(ahdiboot))
409 				err(EXIT_FAILURE, "%s", devnm);
410 			if (verbose)
411 				printf("AHDI root installed on %s (sector 0)\n",
412 				    devnm);
413 		}
414 		if (close(fd))
415 			err(EXIT_FAILURE, "%s", devnm);
416 	}
417 }
418 
419 static void
420 mkahdiboot(struct ahdi_root *newroot, char *xxb00t, char *devnm,
421     u_int32_t bbsec)
422 {
423 	struct ahdi_root tmproot;
424 	struct ahdi_part *pd;
425 	int		 fd;
426 
427 	/* read prototype root-sector */
428 	if ((fd = open(xxb00t, O_RDONLY)) < 0)
429 		err(EXIT_FAILURE, "%s", xxb00t);
430 	if (read(fd, &tmproot, sizeof(tmproot)) != sizeof(tmproot))
431 		err(EXIT_FAILURE, "%s", xxb00t);
432 	if (close(fd))
433 		err(EXIT_FAILURE, "%s", xxb00t);
434 
435 	/* set tracks/cylinder and sectors/track */
436 	setIDEpar(tmproot.ar_fill, sizeof(tmproot.ar_fill));
437 
438 	/* read current root-sector */
439 	if ((fd = open(devnm, O_RDONLY)) < 0)
440 		err(EXIT_FAILURE, "%s", devnm);
441 	if (read(fd, newroot, sizeof(*newroot)) != sizeof(*newroot))
442 		err(EXIT_FAILURE, "%s", devnm);
443 	if (close(fd))
444 		err(EXIT_FAILURE, "%s", devnm);
445 
446 	/* set bootflags */
447 	for (pd = newroot->ar_parts; pd-newroot->ar_parts < AHDI_MAXRPD; ++pd) {
448 		if (pd->ap_st == bbsec) {
449 			pd->ap_flg = 0x21;	/* bootable, pref = NetBSD */
450 			goto gotit;
451 		}
452 	}
453 	errx(EXIT_FAILURE,
454 	     "%s: NetBSD boot block not on primary AHDI partition.", devnm);
455 
456 gotit:	/* copy code from prototype and set new checksum */
457 	memcpy(newroot->ar_fill, tmproot.ar_fill, sizeof(tmproot.ar_fill));
458 	newroot->ar_checksum = 0;
459 	newroot->ar_checksum = 0x1234 - abcksum(newroot);
460 
461 	if (verbose)
462 		printf("AHDI      boot loader: %s\n", xxb00t);
463 }
464 
465 static void
466 mkbootblock(struct bootblock *bb, char *xxb, char *bxx,
467     struct disklabel *label, u_int magic)
468 {
469 	int		 fd;
470 
471 	memset(bb, 0, sizeof(*bb));
472 
473 	/* set boot block magic */
474 	bb->bb_magic = magic;
475 
476 	/* set disk pack label */
477 	BBSETLABEL(bb, label);
478 
479 	/* set second-stage boot loader */
480 	if ((fd = open(bxx, O_RDONLY)) < 0)
481 		err(EXIT_FAILURE, "%s", bxx);
482 	if (read(fd, bb->bb_bootxx, sizeof(bb->bb_bootxx))
483 					!= sizeof(bb->bb_bootxx))
484 		err(EXIT_FAILURE, "%s", bxx);
485 	if (close(fd))
486 		err(EXIT_FAILURE, "%s", bxx);
487 
488 	/* set first-stage bootloader */
489 	if ((fd = open(xxb, O_RDONLY)) < 0)
490 		err(EXIT_FAILURE, "%s", xxb);
491 	if (read(fd, bb->bb_xxboot, sizeof(bb->bb_xxboot))
492 					!= sizeof(bb->bb_xxboot))
493 		err(EXIT_FAILURE, "%s", xxb);
494 	if (close(fd))
495 		err(EXIT_FAILURE, "%s", xxb);
496 
497 	/* set tracks/cylinder and sectors/track */
498 	setIDEpar(bb->bb_xxboot, sizeof(bb->bb_xxboot));
499 
500 	/* set AHDI checksum */
501 	*((u_int16_t *)bb->bb_xxboot + 255) = 0;
502 	*((u_int16_t *)bb->bb_xxboot + 255) = 0x1234 - abcksum(bb->bb_xxboot);
503 
504 	if (verbose) {
505 		printf("Primary   boot loader: %s\n", xxb);
506 		printf("Secondary boot loader: %s\n", bxx);
507 	}
508 }
509 
510 static void
511 setIDEpar (u_int8_t *start, size_t size)
512 {
513 	static const u_int8_t	mark[] = { 'N', 'e', 't', 'B', 'S', 'D' };
514 
515 	if ((u_int)trackpercyl > 255)
516 		errx(EXIT_FAILURE,
517 		     "%d: Illegal tracks/cylinder value (1..255)", trackpercyl);
518 	if ((u_int)secpertrack > 255)
519 		errx(EXIT_FAILURE,
520 		     "%d: Illegal sectors/track value (1..255)", secpertrack);
521 
522 	if (trackpercyl || secpertrack) {
523 		u_int8_t *p;
524 
525 		if (!trackpercyl)
526 			errx(EXIT_FAILURE, "Need tracks/cylinder too.");
527 		if (!secpertrack)
528 			errx(EXIT_FAILURE, "Need sectors/track too.");
529 
530 		start += 2;
531 		size  -= sizeof(mark) + 2;
532 		for (p = start + size; p >= start; --p) {
533 			if (*p != *mark)
534 				continue;
535 			if (!memcmp(p, mark, sizeof(mark)))
536 				break;
537 		}
538 		if (p < start)
539 			errx(EXIT_FAILURE,
540 			     "Malformatted xxboot prototype.");
541 
542 		*--p = secpertrack;
543 		*--p = trackpercyl;
544 
545 		if (verbose) {
546 			printf("sectors/track  : %d\n", secpertrack);
547 			printf("tracks/cylinder: %d\n", trackpercyl);
548 		}
549 	}
550 }
551 
552 static void
553 setNVpref(void)
554 {
555 	static const u_char	bootpref = BOOTPREF_NETBSD;
556 	static const char	nvrdev[] = PATH_NVRAM;
557 
558 	if (!nowrite) {
559 		int	fd;
560 
561 		if ((fd = open(nvrdev, O_RDWR)) < 0)
562 			err(EXIT_FAILURE, "%s", nvrdev);
563 		if (lseek(fd, (off_t)1, SEEK_SET) != 1)
564 			err(EXIT_FAILURE, "%s", nvrdev);
565 		if (write(fd, &bootpref, (size_t)1) != 1)
566 			err(EXIT_FAILURE, "%s", nvrdev);
567 		if (close(fd))
568 			err(EXIT_FAILURE, "%s", nvrdev);
569 		if (verbose)
570 			printf("Boot preference set to NetBSD.\n");
571 	}
572 }
573 
574 static u_int
575 abcksum (void *bs)
576 {
577 	u_int16_t sum  = 0,
578 		  *st  = (u_int16_t *)bs,
579 		  *end = (u_int16_t *)bs + 256;
580 
581 	while (st < end)
582 		sum += *st++;
583 	return(sum);
584 }
585