9ad564373e
>From: bde@kralizec.zeta.org.au (Bruce Evans) Subject: cache botch in bootstrap Date: Sun, 20 Feb 94 18:14:35 +1100 The cache in the bootstrap loader didn't allow for the device changing. This caused surprisingly little trouble - the cache is only for a single track (or part of a track), and the first access to a new device is always for an early sector, so there is no problem unless the last access to the old device was for an early sector. I saw the problem on a system with BSD on wd1 and no label on wd0. Everything worked if the the device name wd(1,a) was specified before the default of wd(0,a) was tried, but when the default was tried, it failed on the first sector because there was no label, and then the first sector on wd0 was always used instead of the first sector on wd1, so there was apparently no label on wd1 either. Bruce
255 lines
6.2 KiB
C
255 lines
6.2 KiB
C
/*
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* Mach Operating System
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* Copyright (c) 1992, 1991 Carnegie Mellon University
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie Mellon
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* the rights to redistribute these changes.
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*
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* from: Mach, Revision 2.2 92/04/04 11:35:49 rpd
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* $Id: disk.c,v 1.3 1993/10/16 19:11:34 rgrimes Exp $
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*/
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#include "boot.h"
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#ifdef DO_BAD144
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#include <sys/dkbad.h>
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#endif DO_BAD144
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#include <sys/disklabel.h>
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#define BIOS_DEV_FLOPPY 0x0
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#define BIOS_DEV_WIN 0x80
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#define BPS 512
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#define SPT(di) ((di)&0xff)
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#define HEADS(di) ((((di)>>8)&0xff)+1)
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char *devs[] = {"wd", "hd", "fd", "wt", "sd", 0};
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#ifdef DO_BAD144
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struct dkbad dkb;
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int do_bad144;
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int bsize;
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#endif DO_BAD144
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int spt, spc;
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char *iodest;
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struct fs *fs;
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struct inode inode;
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int dosdev, unit, part, maj, boff, poff, bnum, cnt;
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/*#define EMBEDDED_DISKLABEL 1*/
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extern struct disklabel disklabel;
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/*struct disklabel disklabel;*/
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devopen()
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{
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struct dos_partition *dptr;
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struct disklabel *dl;
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int dosdev = inode.i_dev;
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int i, sector, di;
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di = get_diskinfo(dosdev);
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spc = (spt = SPT(di)) * HEADS(di);
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if (dosdev == 2)
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{
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boff = 0;
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part = (spt == 15 ? 3 : 1);
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}
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else
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{
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#ifdef EMBEDDED_DISKLABEL
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dl = &disklabel;
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#else EMBEDDED_DISKLABEL
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Bread(dosdev, 0);
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dptr = (struct dos_partition *)(((char *)0)+DOSPARTOFF);
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for (i = 0; i < NDOSPART; i++, dptr++)
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if (dptr->dp_typ == DOSPTYP_386BSD)
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break;
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sector = dptr->dp_start + LABELSECTOR;
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Bread(dosdev, sector++);
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dl=((struct disklabel *)0);
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disklabel = *dl; /* structure copy (maybe useful later)*/
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#endif EMBEDDED_DISKLABEL
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if (dl->d_magic != DISKMAGIC) {
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printf("bad disklabel");
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return 1;
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}
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if( (maj == 4) || (maj == 0) || (maj == 1))
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{
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if (dl->d_type == DTYPE_SCSI)
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{
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maj = 4; /* use scsi as boot dev */
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}
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else
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{
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maj = 0; /* must be ESDI/IDE */
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}
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}
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boff = dl->d_partitions[part].p_offset;
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#ifdef DO_BAD144
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bsize = dl->d_partitions[part].p_size;
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do_bad144 = 0;
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if (dl->d_flags & D_BADSECT) {
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/* this disk uses bad144 */
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int i;
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int dkbbnum;
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struct dkbad *dkbptr;
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/* find the first readable bad144 sector */
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/* some of this code is copied from ufs/disk_subr.c */
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/* read a bad sector table */
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dkbbnum = dl->d_secperunit - dl->d_nsectors;
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if (dl->d_secsize > DEV_BSIZE)
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dkbbnum *= dl->d_secsize / DEV_BSIZE;
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else
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dkbbnum /= DEV_BSIZE / dl->d_secsize;
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i = 0;
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do_bad144 = 0;
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do {
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/* XXX: what if the "DOS sector" < 512 bytes ??? */
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Bread(dosdev, dkbbnum + i);
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dkbptr = (struct dkbad *) 0;
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/* XXX why is this not in <sys/dkbad.h> ??? */
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#define DKBAD_MAGIC 0x4321
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if (dkbptr->bt_mbz == 0 &&
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dkbptr->bt_flag == DKBAD_MAGIC) {
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dkb = *dkbptr; /* structure copy */
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do_bad144 = 1;
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break;
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}
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i += 2;
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} while (i < 10 && i < dl->d_nsectors);
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if (!do_bad144)
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printf("Bad badsect table\n");
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else
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printf("Using bad144 bad sector at %d\n", dkbbnum+i);
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}
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#endif DO_BAD144
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}
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return 0;
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}
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devread()
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{
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int offset, sector = bnum;
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int dosdev = inode.i_dev;
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for (offset = 0; offset < cnt; offset += BPS)
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{
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Bread(dosdev, badsect(dosdev, sector++));
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bcopy(0, iodest+offset, BPS);
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}
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}
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#define I_ADDR ((void *) 0) /* XXX where all reads go */
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/* Read ahead buffer large enough for one track on a 1440K floppy. For
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* reading from floppies, the bootstrap has to be loaded on a 64K boundary
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* to ensure that this buffer doesn't cross a 64K DMA boundary.
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*/
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#define RA_SECTORS 18
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static char ra_buf[RA_SECTORS * BPS];
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static int ra_dev;
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static int ra_end;
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static int ra_first;
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Bread(dosdev,sector)
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int dosdev,sector;
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{
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if (dosdev != ra_dev || sector < ra_first || sector >= ra_end)
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{
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int cyl, head, sec, nsec;
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cyl = sector/spc;
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head = (sector % spc) / spt;
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sec = sector % spt;
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nsec = spt - sec;
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if (nsec > RA_SECTORS)
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nsec = RA_SECTORS;
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twiddle();
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if (biosread(dosdev, cyl, head, sec, nsec, ra_buf) != 0)
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{
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nsec = 1;
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twiddle();
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while (biosread(dosdev, cyl, head, sec, nsec, ra_buf) != 0) {
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printf("Error: C:%d H:%d S:%d\n", cyl, head, sec);
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twiddle();
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}
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}
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ra_dev = dosdev;
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ra_first = sector;
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ra_end = sector + nsec;
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}
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bcopy(ra_buf + (sector - ra_first) * BPS, I_ADDR, BPS);
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}
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badsect(dosdev, sector)
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int dosdev, sector;
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{
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int i;
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#ifdef DO_BAD144
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if (do_bad144) {
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u_short cyl;
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u_short head;
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u_short sec;
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int newsec;
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struct disklabel *dl = &disklabel;
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/* XXX */
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/* from wd.c */
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/* bt_cyl = cylinder number in sorted order */
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/* bt_trksec is actually (head << 8) + sec */
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/* only remap sectors in the partition */
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if (sector < boff || sector >= boff + bsize) {
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goto no_remap;
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}
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cyl = sector / dl->d_secpercyl;
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head = (sector % dl->d_secpercyl) / dl->d_nsectors;
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sec = sector % dl->d_nsectors;
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sec = (head<<8) + sec;
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/* now, look in the table for a possible bad sector */
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for (i=0; i<126; i++) {
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if (dkb.bt_bad[i].bt_cyl == cyl) {
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/* found same cylinder */
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if (dkb.bt_bad[i].bt_trksec == sec) {
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/* FOUND! */
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break;
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}
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} else if (dkb.bt_bad[i].bt_cyl > cyl) {
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i = 126;
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break;
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}
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}
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if (i == 126) {
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/* didn't find bad sector */
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goto no_remap;
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}
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/* otherwise find replacement sector */
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newsec = dl->d_secperunit - dl->d_nsectors - i -1;
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return newsec;
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}
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#endif DO_BAD144
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no_remap:
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return sector;
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}
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