| [4] | 1 | /* This file contains some code to guess where we have to load the
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| 2 | * RAM image device from, if started from CD. (In this case it's hard
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| 3 | * to tell where this is without diving into BIOS heuristics.)
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| 4 | *
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| 5 | * There is some nasty hard-codery in here (e.g. AT minor device numbers,
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| 6 | * MINIX cd label) that can be improved on.
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| 7 | *
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| 8 | * Changes:
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| 9 | * Jul 14, 2005 Created (Ben Gras)
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| 10 | */
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| 11 |
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| 12 | #include "fs.h"
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| 13 | #include "super.h"
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| 14 |
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| 15 | #include <minix/com.h>
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| 16 | #include <string.h>
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| 17 |
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| 18 | /*===========================================================================*
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| 19 | * cdprobe *
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| 20 | *===========================================================================*/
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| 21 | PUBLIC int cdprobe(void)
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| 22 | {
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| 23 | #define CD_SECTOR 2048
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| 24 | #define AT_MAJOR 3
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| 25 | #define AT_MINORS 4
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| 26 | int i, minors[AT_MINORS] = { 0, 5, 10, 15 }, dev = 0, found = 0;
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| 27 | char pvd[CD_SECTOR];
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| 28 | printf("\nLooking for boot CD. This may take a minute.\n"
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| 29 | "Please ignore any error messages.\n\n");
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| 30 | for(i = 0; i < AT_MINORS && !found; i++) {
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| 31 | struct super_block probe_super;
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| 32 | int r, minor;
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| 33 |
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| 34 | dev = (AT_MAJOR << MAJOR) | minors[i];
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| 35 |
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| 36 | /* Open device readonly. (This fails if the device
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| 37 | * is also writable, which a CD isn't.)
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| 38 | */
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| 39 | if ((r = dev_open(dev, FS_PROC_NR, RO_BIT)) != OK) {
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| 40 | continue;
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| 41 | }
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| 42 |
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| 43 | if ((r = dev_io(DEV_READ, dev, FS_PROC_NR, pvd,
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| 44 | 16*CD_SECTOR, sizeof(pvd), 0)) != sizeof(pvd)) {
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| 45 | dev_close(dev);
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| 46 | continue;
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| 47 | }
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| 48 | dev_close(dev);
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| 49 |
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| 50 | /* Check PVD ID. */
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| 51 | if (pvd[0] != 1 || pvd[1] != 'C' || pvd[2] != 'D' ||
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| 52 | pvd[3] != '0' || pvd[4] != '0' || pvd[5] != '1' || pvd[6] != 1 ||
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| 53 | strncmp(pvd + 40, "MINIX", 5)) {
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| 54 | continue;
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| 55 | }
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| 56 |
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| 57 | /* 3. Both c0dXp1 and p2 should have a superblock. */
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| 58 | for(minor = minors[i]+2; minor <= minors[i]+3; minor++) {
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| 59 | dev = (AT_MAJOR << MAJOR) | minor;
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| 60 | if ((r = dev_open(dev, FS_PROC_NR, R_BIT)) != OK) {
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| 61 | break;
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| 62 | }
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| 63 | probe_super.s_dev = dev;
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| 64 | r = read_super(&probe_super);
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| 65 | dev_close(dev);
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| 66 | if (r != OK) {
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| 67 | break;
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| 68 | }
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| 69 | }
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| 70 |
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| 71 | if (minor > minors[i]+3) {
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| 72 | /* Success? Then set dev to p1. */
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| 73 | dev = (AT_MAJOR << MAJOR) | (minors[i]+2);
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| 74 | found = 1;
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| 75 | break;
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| 76 | }
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| 77 | }
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| 78 |
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| 79 | if (!found) return NO_DEV;
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| 80 |
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| 81 | return dev;
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| 82 | }
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| 83 |
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