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Groups > comp.os.linux.setup > #841
| From | Arno <me@privacy.net> |
|---|---|
| Newsgroups | comp.os.linux.setup, comp.unix.programmer, comp.sys.ibm.pc.hardware.storage |
| Subject | Re: Help, the dog ate my MBR (Linux/Windows dual boot) |
| Date | 2011-07-22 18:41 +0000 |
| Message-ID | <98tuhvF8k5U1@mid.individual.net> (permalink) |
| References | <4e28ac1d$0$14975$426a74cc@news.free.fr> <j0c18i$6v4$1@dont-email.me> |
Cross-posted to 3 groups.
In comp.sys.ibm.pc.hardware.storage Noob <root@127.0.0.1> wrote: > [ Please note that I've added comp.sys.ibm.pc.hardware.storage > to the list of newsgroups ] > Noob wrote: >> Something trashed my MBR. Now when I boot the PC, >> I get the dreaded "NON-SYSTEM DISK. PLEASE INSERT >> SYSTEM DISK AND PRESS ENTER" (or something close). > By MBR, I meant the first sector of my hard disk drive, > i.e. the boot-strapping code, and the table of primary > partitions. >> My setup: >> PATA 120-GB HDD on IDE0 master >> PATA DVD reader on IDE1 master >> No IDE slaves. No SATA drives. (SATA disabled in BIOS) >> >> I had used gparted to create three primary partitions >> (all partitions are aligned to 1 MiB, even though >> this is not a 4K-sector HDD) >> partition 1 : 80.00 GiB (for WinXP) >> partition 2 : 33.75 GiB (for Fedora 13) >> partition 3 : 765 MiB (for swap) > Short version of the rest of original message : the first sector > had been shifted by 14 bytes. Weird, right? Very much so, indeed. A 14 byte offset seems next to impossible. > And the plot thickens. Later that same night, I copied the > MBR a second time in the live CD environment; and this second > time, the first 14 bytes of the MBR were ZERO, i.e. > they had changed !! > Even stranger, the next morning, I booted the PC, > and the 14-byte offset had disappeared. > I'm starting to think that this might be a hardware problem, > as both Linux AND the BIOS seem to have had troubles getting > the MBR consistently. Something else I haven't mentioned: > when Windows resumes from hibernation, the whole system > sometime reboots (this started about 2/3 weeks ago), around > the same time I changed the RAM from 2x512 to 2x1024. This is typical for bad RAM. Unfortunately bad RAM can be hard to detect. I once had to run memtest86+ for 3 days to identify a bad module. Put in the old modules and try to recreate the problem. > I tested the RAM, no errors after one hour of checking. > The S.M.A.R.T. counters for the HDD claim the drive is > "healthy". > However, considering that the drive is inserting random > garbage around requested data, I'm wondering if this could > be the drive's controller failing? Would this show up in > a S.M.A.R.T. diagnostic? No. SMART is just done on the disk itself. You may find interface errors in the error log, but only if there are chacksums on the data/commands. With PATA there are no checksums on the commands and on the data only with ATA-66 and above. > Or am I on the wrong track, and do you see something else > that might be responsible? Well, it could be a very obscure hardware problem. But are you sure you are using your tools right? I had things like this happen to me, only to realize later that the problem was before the keyboard. That said, PATA is subject to both data and command corruption with bad cables or not fully plugged connectors. Even >= ATA-66 only has checksums on the data, not the commands. If you have non-spec cables (>45cm, rounded), the next test would be to replace them with spec cables and try again. Also, bad RAM can have arbitrary effects. From nothing at all to very strange things as abserverd by you. Arno > [ Below is the rest of my original message, which I left in > because of the belated cross-post to csiphs ] >> For my own record, my partitions are encoded as follows. >> >> http://en.wikipedia.org/wiki/Master_boot_record >> http://en.wikipedia.org/wiki/Partition_type >> >> 80 20 21 00 07 fe ff ff 00 08 00 00 00 00 00 0a >> bootable, NTFS, start = 1 MiB, count = 80 GiB >> >> 00 fe ff ff 83 fe ff ff 00 08 00 0a 00 00 38 04 >> non-bootable, linux, count = 33.75 GiB >> >> 00 fe ff ff 82 fe ff ff 00 08 38 0e 00 e8 17 00 >> non-bootable, swap, count = 765 MiB >> >> I used a Fedora 15 live CD to boot to Linux, and examine >> the MBR. I looked for the MBR signature, and noticed >> something very odd: the 0xAA55 signature was 14 bytes >> "too far", i.e. at offset 0x20c instead of 0x1fe, which >> means my broken MBR straddles sectors 0 and 1... >> >> # cat broken_mbr.dump >> 00000000 00 00 00 00 00 00 41 01 63 74 e6 00 39 00 eb 48 |......A.ct..9..H| >> 00000010 90 d0 bc 00 7c fb 50 07 50 1f fc be 1b 7c bf 1b |....|.P.P....|..| >> 00000020 06 50 57 b9 e5 01 f3 a4 cb bd be 07 b1 04 38 6e |.PW...........8n| >> 00000030 00 7c 09 75 13 83 c5 10 e2 f4 cd 18 8b f5 83 c6 |.|.u............| >> 00000040 10 49 74 19 38 2c 74 f6 a0 b5 07 b4 03 02 80 00 |.It.8,t.........| >> 00000050 00 80 00 e8 c4 0a 00 08 fa 90 90 f6 c2 80 75 02 |..............u.| >> 00000060 b2 80 ea 59 7c 00 00 31 c0 8e d8 8e d0 bc 00 20 |...Y|..1....... | >> 00000070 fb a0 40 7c 3c ff 74 02 88 c2 52 f6 c2 80 74 54 |..@|<.t...R...tT| >> 00000080 b4 41 bb aa 55 cd 13 5a 52 72 49 81 fb 55 aa 75 |.A..U..ZRrI..U.u| >> 00000090 43 a0 41 7c 84 c0 75 05 83 e1 01 74 37 66 8b 4c |C.A|..u....t7f.L| >> 000000a0 10 be 05 7c c6 44 ff 01 66 8b 1e 44 7c c7 04 10 |...|.D..f..D|...| >> 000000b0 00 c7 44 02 01 00 66 89 5c 08 c7 44 06 00 70 66 |..D...f.\..D..pf| >> 000000c0 31 c0 89 44 04 66 89 44 0c b4 42 cd 13 72 05 bb |1..D.f.D..B..r..| >> 000000d0 00 70 eb 7d b4 08 cd 13 73 0a f6 c2 80 0f 84 f0 |.p.}....s.......| >> 000000e0 00 e9 8d 00 be 05 7c c6 44 ff 00 66 31 c0 88 f0 |......|.D..f1...| >> 000000f0 40 66 89 44 04 31 d2 88 ca c1 e2 02 88 e8 88 f4 |@f.D.1..........| >> 00000100 40 89 44 08 31 c0 88 d0 c0 e8 02 66 89 04 66 a1 |@.D.1......f..f.| >> 00000110 44 7c 66 31 d2 66 f7 34 88 54 0a 66 31 d2 66 f7 |D|f1.f.4.T.f1.f.| >> 00000120 74 04 88 54 0b 89 44 0c 3b 44 08 7d 3c 8a 54 0d |t..T..D.;D.}<.T.| >> 00000130 c0 e2 06 8a 4c 0a fe c1 08 d1 8a 6c 0c 5a 8a 74 |....L......l.Z.t| >> 00000140 0b bb 00 70 8e c3 31 db b8 01 02 cd 13 72 2a 8c |...p..1......r*.| >> 00000150 c3 8e 06 48 7c 60 1e b9 00 01 8e db 31 f6 31 ff |...H|`......1.1.| >> 00000160 fc f3 a5 1f 61 ff 26 42 7c be 7f 7d e8 40 00 eb |....a.&B|..}.@..| >> 00000170 0e be 84 7d e8 38 00 eb 06 be 8e 7d e8 30 00 be |...}.8.....}.0..| >> 00000180 93 7d e8 2a 00 eb fe 47 52 55 42 20 00 47 65 6f |.}.*...GRUB .Geo| >> 00000190 6d 00 48 61 72 64 20 44 69 73 6b 00 52 65 61 64 |m.Hard Disk.Read| >> 000001a0 00 20 45 72 72 6f 72 00 bb 01 00 b4 0e cd 10 ac |. Error.........| >> 000001b0 3c 00 75 f4 c3 00 00 00 00 00 00 00 00 00 00 00 |<.u.............| >> 000001c0 00 00 00 00 00 00 dc 3b dd 3b 00 00 80 20 21 00 |.......;.;... !.| >> 000001d0 07 fe ff ff 00 08 00 00 00 00 00 0a 00 fe ff ff |................| >> 000001e0 83 fe ff ff 00 08 00 0a 00 00 38 04 00 fe ff ff |..........8.....| >> 000001f0 82 fe ff ff 00 08 38 0e 00 e8 17 00 00 00 00 00 |......8.........| >> 00000200 00 00 00 00 00 00 00 00 00 00 00 00 55 aa 00 00 |............U...| >> 00000210 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| >> >> The partition table (64 bytes) at the end, right >> before the last two-byte signature, is valid. >> >> For comparison, I examined /boot/grub/stage1 >> >> # cat good_mbr.dump >> 00000000 eb 48 90 00 00 00 00 00 00 00 00 00 00 00 00 00 |.H..............| >> 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| >> * >> 00000030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 02 |................| >> 00000040 ff 00 00 80 01 00 00 00 00 08 fa eb 07 f6 c2 80 |................| >> 00000050 75 02 b2 80 ea 59 7c 00 00 31 c0 8e d8 8e d0 bc |u....Y|..1......| >> 00000060 00 20 fb a0 40 7c 3c ff 74 02 88 c2 52 f6 c2 80 |. ..@|<.t...R...| >> 00000070 74 54 b4 41 bb aa 55 cd 13 5a 52 72 49 81 fb 55 |tT.A..U..ZRrI..U| >> 00000080 aa 75 43 a0 41 7c 84 c0 75 05 83 e1 01 74 37 66 |.uC.A|..u....t7f| >> 00000090 8b 4c 10 be 05 7c c6 44 ff 01 66 8b 1e 44 7c c7 |.L...|.D..f..D|.| >> 000000a0 04 10 00 c7 44 02 01 00 66 89 5c 08 c7 44 06 00 |....D...f.\..D..| >> 000000b0 70 66 31 c0 89 44 04 66 89 44 0c b4 42 cd 13 72 |pf1..D.f.D..B..r| >> 000000c0 05 bb 00 70 eb 7d b4 08 cd 13 73 0a f6 c2 80 0f |...p.}....s.....| >> 000000d0 84 f0 00 e9 8d 00 be 05 7c c6 44 ff 00 66 31 c0 |........|.D..f1.| >> 000000e0 88 f0 40 66 89 44 04 31 d2 88 ca c1 e2 02 88 e8 |..@f.D.1........| >> 000000f0 88 f4 40 89 44 08 31 c0 88 d0 c0 e8 02 66 89 04 |..@.D.1......f..| >> 00000100 66 a1 44 7c 66 31 d2 66 f7 34 88 54 0a 66 31 d2 |f.D|f1.f.4.T.f1.| >> 00000110 66 f7 74 04 88 54 0b 89 44 0c 3b 44 08 7d 3c 8a |f.t..T..D.;D.}<.| >> 00000120 54 0d c0 e2 06 8a 4c 0a fe c1 08 d1 8a 6c 0c 5a |T.....L......l.Z| >> 00000130 8a 74 0b bb 00 70 8e c3 31 db b8 01 02 cd 13 72 |.t...p..1......r| >> 00000140 2a 8c c3 8e 06 48 7c 60 1e b9 00 01 8e db 31 f6 |*....H|`......1.| >> 00000150 31 ff fc f3 a5 1f 61 ff 26 42 7c be 7f 7d e8 40 |1.....a.&B|..}.@| >> 00000160 00 eb 0e be 84 7d e8 38 00 eb 06 be 8e 7d e8 30 |.....}.8.....}.0| >> 00000170 00 be 93 7d e8 2a 00 eb fe 47 52 55 42 20 00 47 |...}.*...GRUB .G| >> 00000180 65 6f 6d 00 48 61 72 64 20 44 69 73 6b 00 52 65 |eom.Hard Disk.Re| >> 00000190 61 64 00 20 45 72 72 6f 72 00 bb 01 00 b4 0e cd |ad. Error.......| >> 000001a0 10 ac 3c 00 75 f4 c3 00 00 00 00 00 00 00 00 00 |..<.u...........| >> 000001b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 24 12 |..............$.| >> 000001c0 0f 09 00 be bd 7d 31 c0 cd 13 46 8a 0c 80 f9 00 |.....}1...F.....| >> 000001d0 75 0f be da 7d e8 c9 ff eb 97 46 6c 6f 70 70 79 |u...}.....Floppy| >> 000001e0 00 bb 00 70 b8 01 02 b5 00 b6 00 cd 13 72 d7 b6 |...p.........r..| >> 000001f0 01 b5 4f e9 e0 fe 00 00 00 00 00 00 00 00 55 aa |..O...........U.| >> >> And indeed, the "eb 48" is there in my broken MBR, >> 14 bytes "too far". So it looks like I could just >> use a binary editor to remove the first 14 bytes, >> then write that back to my HDD's first sector? >> >> Not too sure about that, though. >> >> Does my broken MBR, shifted left by 14 bytes, look >> like a valid MBR for grub? >> >> Thoughts? Suggestions? How should I proceed? >> >> For the record, here are the disassembly for the >> broken MBR, and the good MBR (they do seem to differ >> in several places, I'm wondering if this is because >> I shouldn't be looking at /boot/grub/stage1) >> >> On a normal MBR, the code area ranges from 0 to 0x1b7 >> Shifted by 14 bytes, I expect range 14 to 0x1c5 >> >> http://prefetch.net/blog/index.php/2006/09/09/digging-through-the-mbr/ >> >> # cat broken_mbr.asm >> 0: 00 00 add %al,(%bx,%si) >> 2: 00 00 add %al,(%bx,%si) >> 4: 00 00 add %al,(%bx,%si) >> 6: 41 inc %cx >> 7: 01 63 74 add %sp,0x74(%bp,%di) >> a: e6 00 out %al,$0x0 >> c: 39 00 cmp %ax,(%bx,%si) >> XXX e: eb 48 jmp 0x58 >> 10: 90 nop >> 11: d0 bc 00 7c sarb 0x7c00(%si) >> 15: fb sti >> 16: 50 push %ax >> 17: 07 pop %es >> 18: 50 push %ax >> 19: 1f pop %ds >> 1a: fc cld >> 1b: be 1b 7c mov $0x7c1b,%si >> 1e: bf 1b 06 mov $0x61b,%di >> 21: 50 push %ax >> 22: 57 push %di >> 23: b9 e5 01 mov $0x1e5,%cx >> 26: f3 a4 rep movsb %ds:(%si),%es:(%di) >> 28: cb lret >> 29: bd be 07 mov $0x7be,%bp >> 2c: b1 04 mov $0x4,%cl >> 2e: 38 6e 00 cmp %ch,0x0(%bp) >> 31: 7c 09 jl 0x3c >> 33: 75 13 jne 0x48 >> 35: 83 c5 10 add $0x10,%bp >> 38: e2 f4 loop 0x2e >> 3a: cd 18 int $0x18 >> 3c: 8b f5 mov %bp,%si >> 3e: 83 c6 10 add $0x10,%si >> 41: 49 dec %cx >> 42: 74 19 je 0x5d >> 44: 38 2c cmp %ch,(%si) >> 46: 74 f6 je 0x3e >> 48: a0 b5 07 mov 0x7b5,%al >> 4b: b4 03 mov $0x3,%ah >> 4d: 02 80 00 00 add 0x0(%bx,%si),%al >> 51: 80 00 e8 addb $0xe8,(%bx,%si) >> 54: c4 0a les (%bp,%si),%cx >> 56: 00 08 add %cl,(%bx,%si) >> 58: fa cli >> 59: 90 nop >> 5a: 90 nop >> 5b: f6 c2 80 test $0x80,%dl >> 5e: 75 02 jne 0x62 >> 60: b2 80 mov $0x80,%dl >> 62: ea 59 7c 00 00 ljmp $0x0,$0x7c59 >> 67: 31 c0 xor %ax,%ax >> 69: 8e d8 mov %ax,%ds >> 6b: 8e d0 mov %ax,%ss >> 6d: bc 00 20 mov $0x2000,%sp >> 70: fb sti >> 71: a0 40 7c mov 0x7c40,%al >> 74: 3c ff cmp $0xff,%al >> 76: 74 02 je 0x7a >> 78: 88 c2 mov %al,%dl >> 7a: 52 push %dx >> 7b: f6 c2 80 test $0x80,%dl >> 7e: 74 54 je 0xd4 >> 80: b4 41 mov $0x41,%ah >> 82: bb aa 55 mov $0x55aa,%bx >> 85: cd 13 int $0x13 >> 87: 5a pop %dx >> 88: 52 push %dx >> 89: 72 49 jb 0xd4 >> 8b: 81 fb 55 aa cmp $0xaa55,%bx >> 8f: 75 43 jne 0xd4 >> 91: a0 41 7c mov 0x7c41,%al >> 94: 84 c0 test %al,%al >> 96: 75 05 jne 0x9d >> 98: 83 e1 01 and $0x1,%cx >> 9b: 74 37 je 0xd4 >> 9d: 66 8b 4c 10 mov 0x10(%si),%ecx >> a1: be 05 7c mov $0x7c05,%si >> a4: c6 44 ff 01 movb $0x1,-0x1(%si) >> a8: 66 8b 1e 44 7c mov 0x7c44,%ebx >> ad: c7 04 10 00 movw $0x10,(%si) >> b1: c7 44 02 01 00 movw $0x1,0x2(%si) >> b6: 66 89 5c 08 mov %ebx,0x8(%si) >> ba: c7 44 06 00 70 movw $0x7000,0x6(%si) >> bf: 66 31 c0 xor %eax,%eax >> c2: 89 44 04 mov %ax,0x4(%si) >> c5: 66 89 44 0c mov %eax,0xc(%si) >> c9: b4 42 mov $0x42,%ah >> cb: cd 13 int $0x13 >> cd: 72 05 jb 0xd4 >> cf: bb 00 70 mov $0x7000,%bx >> d2: eb 7d jmp 0x151 >> d4: b4 08 mov $0x8,%ah >> d6: cd 13 int $0x13 >> d8: 73 0a jae 0xe4 >> da: f6 c2 80 test $0x80,%dl >> dd: 0f 84 f0 00 je 0x1d1 >> e1: e9 8d 00 jmp 0x171 >> e4: be 05 7c mov $0x7c05,%si >> e7: c6 44 ff 00 movb $0x0,-0x1(%si) >> eb: 66 31 c0 xor %eax,%eax >> ee: 88 f0 mov %dh,%al >> f0: 40 inc %ax >> f1: 66 89 44 04 mov %eax,0x4(%si) >> f5: 31 d2 xor %dx,%dx >> f7: 88 ca mov %cl,%dl >> f9: c1 e2 02 shl $0x2,%dx >> fc: 88 e8 mov %ch,%al >> fe: 88 f4 mov %dh,%ah >> 100: 40 inc %ax >> 101: 89 44 08 mov %ax,0x8(%si) >> 104: 31 c0 xor %ax,%ax >> 106: 88 d0 mov %dl,%al >> 108: c0 e8 02 shr $0x2,%al >> 10b: 66 89 04 mov %eax,(%si) >> 10e: 66 a1 44 7c mov 0x7c44,%eax >> 112: 66 31 d2 xor %edx,%edx >> 115: 66 f7 34 divl (%si) >> 118: 88 54 0a mov %dl,0xa(%si) >> 11b: 66 31 d2 xor %edx,%edx >> 11e: 66 f7 74 04 divl 0x4(%si) >> 122: 88 54 0b mov %dl,0xb(%si) >> 125: 89 44 0c mov %ax,0xc(%si) >> 128: 3b 44 08 cmp 0x8(%si),%ax >> 12b: 7d 3c jge 0x169 >> 12d: 8a 54 0d mov 0xd(%si),%dl >> 130: c0 e2 06 shl $0x6,%dl >> 133: 8a 4c 0a mov 0xa(%si),%cl >> 136: fe c1 inc %cl >> 138: 08 d1 or %dl,%cl >> 13a: 8a 6c 0c mov 0xc(%si),%ch >> 13d: 5a pop %dx >> 13e: 8a 74 0b mov 0xb(%si),%dh >> 141: bb 00 70 mov $0x7000,%bx >> 144: 8e c3 mov %bx,%es >> 146: 31 db xor %bx,%bx >> 148: b8 01 02 mov $0x201,%ax >> 14b: cd 13 int $0x13 >> 14d: 72 2a jb 0x179 >> 14f: 8c c3 mov %es,%bx >> 151: 8e 06 48 7c mov 0x7c48,%es >> 155: 60 pusha >> 156: 1e push %ds >> 157: b9 00 01 mov $0x100,%cx >> 15a: 8e db mov %bx,%ds >> 15c: 31 f6 xor %si,%si >> 15e: 31 ff xor %di,%di >> 160: fc cld >> 161: f3 a5 rep movsw %ds:(%si),%es:(%di) >> 163: 1f pop %ds >> 164: 61 popa >> 165: ff 26 42 7c jmp *0x7c42 >> 169: be 7f 7d mov $0x7d7f,%si >> 16c: e8 40 00 call 0x1af >> 16f: eb 0e jmp 0x17f >> 171: be 84 7d mov $0x7d84,%si >> 174: e8 38 00 call 0x1af >> 177: eb 06 jmp 0x17f >> 179: be 8e 7d mov $0x7d8e,%si >> 17c: e8 30 00 call 0x1af >> 17f: be 93 7d mov $0x7d93,%si >> 182: e8 2a 00 call 0x1af >> 185: eb fe jmp 0x185 >> 187: 47 inc %di >> 188: 52 push %dx >> 189: 55 push %bp >> 18a: 42 inc %dx >> 18b: 20 00 and %al,(%bx,%si) >> 18d: 47 inc %di >> 18e: 65 6f outsw %gs:(%si),(%dx) >> 190: 6d insw (%dx),%es:(%di) >> 191: 00 48 61 add %cl,0x61(%bx,%si) >> 194: 72 64 jb 0x1fa >> 196: 20 44 69 and %al,0x69(%si) >> 199: 73 6b jae 0x206 >> 19b: 00 52 65 add %dl,0x65(%bp,%si) >> 19e: 61 popa >> 19f: 64 00 20 add %ah,%fs:(%bx,%si) >> 1a2: 45 inc %bp >> 1a3: 72 72 jb 0x217 >> 1a5: 6f outsw %ds:(%si),(%dx) >> 1a6: 72 00 jb 0x1a8 >> 1a8: bb 01 00 mov $0x1,%bx >> 1ab: b4 0e mov $0xe,%ah >> 1ad: cd 10 int $0x10 >> 1af: ac lods %ds:(%si),%al >> 1b0: 3c 00 cmp $0x0,%al >> 1b2: 75 f4 jne 0x1a8 >> 1b4: c3 ret >> ... >> !!! DATA (NOT CODE) BELOW THISPOINT (AFAIU) !!! >> 1c5: 00 dc add %bl,%ah >> 1c7: 3b dd cmp %bp,%bx >> 1c9: 3b 00 cmp (%bx,%si),%ax >> 1cb: 00 80 20 21 add %al,0x2120(%bx,%si) >> 1cf: 00 07 add %al,(%bx) >> 1d1: fe (bad) >> 1d2: ff (bad) >> 1d3: ff 00 incw (%bx,%si) >> 1d5: 08 00 or %al,(%bx,%si) >> 1d7: 00 00 add %al,(%bx,%si) >> 1d9: 00 00 add %al,(%bx,%si) >> 1db: 0a 00 or (%bx,%si),%al >> 1dd: fe (bad) >> 1de: ff (bad) >> 1df: ff 83 fe ff incw -0x2(%bp,%di) >> 1e3: ff 00 incw (%bx,%si) >> 1e5: 08 00 or %al,(%bx,%si) >> 1e7: 0a 00 or (%bx,%si),%al >> 1e9: 00 38 add %bh,(%bx,%si) >> 1eb: 04 00 add $0x0,%al >> 1ed: fe (bad) >> 1ee: ff (bad) >> 1ef: ff 82 fe ff incw -0x2(%bp,%si) >> 1f3: ff 00 incw (%bx,%si) >> 1f5: 08 38 or %bh,(%bx,%si) >> 1f7: 0e push %cs >> 1f8: 00 e8 add %ch,%al >> 1fa: 17 pop %ss >> ... >> 20b: 00 55 aa add %dl,-0x56(%di) >> >> >> # cat good_mbr.asm >> 0: eb 48 jmp 0x4a >> 2: 90 nop >> ... >> 3b: 00 00 add %al,(%bx,%si) >> 3d: 00 03 add %al,(%bp,%di) >> 3f: 02 ff add %bh,%bh >> 41: 00 00 add %al,(%bx,%si) >> 43: 80 01 00 addb $0x0,(%bx,%di) >> 46: 00 00 add %al,(%bx,%si) >> 48: 00 08 add %cl,(%bx,%si) >> 4a: fa cli >> 4b: eb 07 jmp 0x54 >> 4d: f6 c2 80 test $0x80,%dl >> 50: 75 02 jne 0x54 >> 52: b2 80 mov $0x80,%dl >> 54: ea 59 7c 00 00 ljmp $0x0,$0x7c59 >> 59: 31 c0 xor %ax,%ax >> 5b: 8e d8 mov %ax,%ds >> 5d: 8e d0 mov %ax,%ss >> 5f: bc 00 20 mov $0x2000,%sp >> 62: fb sti >> 63: a0 40 7c mov 0x7c40,%al >> 66: 3c ff cmp $0xff,%al >> 68: 74 02 je 0x6c >> 6a: 88 c2 mov %al,%dl >> 6c: 52 push %dx >> 6d: f6 c2 80 test $0x80,%dl >> 70: 74 54 je 0xc6 >> 72: b4 41 mov $0x41,%ah >> 74: bb aa 55 mov $0x55aa,%bx >> 77: cd 13 int $0x13 >> 79: 5a pop %dx >> 7a: 52 push %dx >> 7b: 72 49 jb 0xc6 >> 7d: 81 fb 55 aa cmp $0xaa55,%bx >> 81: 75 43 jne 0xc6 >> 83: a0 41 7c mov 0x7c41,%al >> 86: 84 c0 test %al,%al >> 88: 75 05 jne 0x8f >> 8a: 83 e1 01 and $0x1,%cx >> 8d: 74 37 je 0xc6 >> 8f: 66 8b 4c 10 mov 0x10(%si),%ecx >> 93: be 05 7c mov $0x7c05,%si >> 96: c6 44 ff 01 movb $0x1,-0x1(%si) >> 9a: 66 8b 1e 44 7c mov 0x7c44,%ebx >> 9f: c7 04 10 00 movw $0x10,(%si) >> a3: c7 44 02 01 00 movw $0x1,0x2(%si) >> a8: 66 89 5c 08 mov %ebx,0x8(%si) >> ac: c7 44 06 00 70 movw $0x7000,0x6(%si) >> b1: 66 31 c0 xor %eax,%eax >> b4: 89 44 04 mov %ax,0x4(%si) >> b7: 66 89 44 0c mov %eax,0xc(%si) >> bb: b4 42 mov $0x42,%ah >> bd: cd 13 int $0x13 >> bf: 72 05 jb 0xc6 >> c1: bb 00 70 mov $0x7000,%bx >> c4: eb 7d jmp 0x143 >> c6: b4 08 mov $0x8,%ah >> c8: cd 13 int $0x13 >> ca: 73 0a jae 0xd6 >> cc: f6 c2 80 test $0x80,%dl >> cf: 0f 84 f0 00 je 0x1c3 >> d3: e9 8d 00 jmp 0x163 >> d6: be 05 7c mov $0x7c05,%si >> d9: c6 44 ff 00 movb $0x0,-0x1(%si) >> dd: 66 31 c0 xor %eax,%eax >> e0: 88 f0 mov %dh,%al >> e2: 40 inc %ax >> e3: 66 89 44 04 mov %eax,0x4(%si) >> e7: 31 d2 xor %dx,%dx >> e9: 88 ca mov %cl,%dl >> eb: c1 e2 02 shl $0x2,%dx >> ee: 88 e8 mov %ch,%al >> f0: 88 f4 mov %dh,%ah >> f2: 40 inc %ax >> f3: 89 44 08 mov %ax,0x8(%si) >> f6: 31 c0 xor %ax,%ax >> f8: 88 d0 mov %dl,%al >> fa: c0 e8 02 shr $0x2,%al >> fd: 66 89 04 mov %eax,(%si) >> 100: 66 a1 44 7c mov 0x7c44,%eax >> 104: 66 31 d2 xor %edx,%edx >> 107: 66 f7 34 divl (%si) >> 10a: 88 54 0a mov %dl,0xa(%si) >> 10d: 66 31 d2 xor %edx,%edx >> 110: 66 f7 74 04 divl 0x4(%si) >> 114: 88 54 0b mov %dl,0xb(%si) >> 117: 89 44 0c mov %ax,0xc(%si) >> 11a: 3b 44 08 cmp 0x8(%si),%ax >> 11d: 7d 3c jge 0x15b >> 11f: 8a 54 0d mov 0xd(%si),%dl >> 122: c0 e2 06 shl $0x6,%dl >> 125: 8a 4c 0a mov 0xa(%si),%cl >> 128: fe c1 inc %cl >> 12a: 08 d1 or %dl,%cl >> 12c: 8a 6c 0c mov 0xc(%si),%ch >> 12f: 5a pop %dx >> 130: 8a 74 0b mov 0xb(%si),%dh >> 133: bb 00 70 mov $0x7000,%bx >> 136: 8e c3 mov %bx,%es >> 138: 31 db xor %bx,%bx >> 13a: b8 01 02 mov $0x201,%ax >> 13d: cd 13 int $0x13 >> 13f: 72 2a jb 0x16b >> 141: 8c c3 mov %es,%bx >> 143: 8e 06 48 7c mov 0x7c48,%es >> 147: 60 pusha >> 148: 1e push %ds >> 149: b9 00 01 mov $0x100,%cx >> 14c: 8e db mov %bx,%ds >> 14e: 31 f6 xor %si,%si >> 150: 31 ff xor %di,%di >> 152: fc cld >> 153: f3 a5 rep movsw %ds:(%si),%es:(%di) >> 155: 1f pop %ds >> 156: 61 popa >> 157: ff 26 42 7c jmp *0x7c42 >> 15b: be 7f 7d mov $0x7d7f,%si >> 15e: e8 40 00 call 0x1a1 >> 161: eb 0e jmp 0x171 >> 163: be 84 7d mov $0x7d84,%si >> 166: e8 38 00 call 0x1a1 >> 169: eb 06 jmp 0x171 >> 16b: be 8e 7d mov $0x7d8e,%si >> 16e: e8 30 00 call 0x1a1 >> 171: be 93 7d mov $0x7d93,%si >> 174: e8 2a 00 call 0x1a1 >> 177: eb fe jmp 0x177 >> 179: 47 inc %di >> 17a: 52 push %dx >> 17b: 55 push %bp >> 17c: 42 inc %dx >> 17d: 20 00 and %al,(%bx,%si) >> 17f: 47 inc %di >> 180: 65 6f outsw %gs:(%si),(%dx) >> 182: 6d insw (%dx),%es:(%di) >> 183: 00 48 61 add %cl,0x61(%bx,%si) >> 186: 72 64 jb 0x1ec >> 188: 20 44 69 and %al,0x69(%si) >> 18b: 73 6b jae 0x1f8 >> 18d: 00 52 65 add %dl,0x65(%bp,%si) >> 190: 61 popa >> 191: 64 00 20 add %ah,%fs:(%bx,%si) >> 194: 45 inc %bp >> 195: 72 72 jb 0x209 >> 197: 6f outsw %ds:(%si),(%dx) >> 198: 72 00 jb 0x19a >> 19a: bb 01 00 mov $0x1,%bx >> 19d: b4 0e mov $0xe,%ah >> 19f: cd 10 int $0x10 >> 1a1: ac lods %ds:(%si),%al >> 1a2: 3c 00 cmp $0x0,%al >> 1a4: 75 f4 jne 0x19a >> 1a6: c3 ret >> ... >> !!! DATA (NOT CODE) BELOW THIS POINT (AFAIU) !!! >> 1bb: 00 00 add %al,(%bx,%si) >> 1bd: 00 24 add %ah,(%si) >> 1bf: 12 0f adc (%bx),%cl >> 1c1: 09 00 or %ax,(%bx,%si) >> 1c3: be bd 7d mov $0x7dbd,%si >> 1c6: 31 c0 xor %ax,%ax >> 1c8: cd 13 int $0x13 >> 1ca: 46 inc %si >> 1cb: 8a 0c mov (%si),%cl >> 1cd: 80 f9 00 cmp $0x0,%cl >> 1d0: 75 0f jne 0x1e1 >> 1d2: be da 7d mov $0x7dda,%si >> 1d5: e8 c9 ff call 0x1a1 >> 1d8: eb 97 jmp 0x171 >> 1da: 46 inc %si >> 1db: 6c insb (%dx),%es:(%di) >> 1dc: 6f outsw %ds:(%si),(%dx) >> 1dd: 70 70 jo 0x24f >> 1df: 79 00 jns 0x1e1 >> 1e1: bb 00 70 mov $0x7000,%bx >> 1e4: b8 01 02 mov $0x201,%ax >> 1e7: b5 00 mov $0x0,%ch >> 1e9: b6 00 mov $0x0,%dh >> 1eb: cd 13 int $0x13 >> 1ed: 72 d7 jb 0x1c6 >> 1ef: b6 01 mov $0x1,%dh >> 1f1: b5 4f mov $0x4f,%ch >> 1f3: e9 e0 fe jmp 0xd6 >> ... >> 1fe: 55 push %bp >> 1ff: aa stos %al,%es:(%di) >> >> Thanks for reading this far!! ;-) >> >> Regards. -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@wagner.name GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
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Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@localhost> - 2011-07-22 00:45 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Ian Collins <ian-news@hotmail.com> - 2011-07-22 10:50 +1200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@localhost> - 2011-07-22 01:26 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Paul <nospam@needed.com> - 2011-07-21 19:38 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-22 16:29 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Paul <nospam@needed.com> - 2011-07-22 14:28 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) g.fink@gmx.net (Gernot Fink) - 2011-07-22 04:35 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Mike Easter <MikeE@ster.invalid> - 2011-07-21 19:20 -0700
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-22 11:00 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) GangGreene <GangGreene@invalid.com> - 2011-07-22 05:29 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-22 12:01 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) g.fink@gmx.net (Gernot Fink) - 2011-07-22 10:28 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2011-07-21 23:33 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) BGB <cr88192@hotmail.com> - 2011-07-21 21:26 -0700
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-22 16:25 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Bob Willard <BobwBSGS@TrashThis.comcast.net> - 2011-07-22 12:17 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-22 18:35 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Arno <me@privacy.net> - 2011-07-22 18:41 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Paul <nospam@needed.com> - 2011-07-22 14:52 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) The Natural Philosopher <tnp@invalid.invalid> - 2011-07-23 02:23 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) scott@slp53.sl.home (Scott Lurndal) - 2011-07-22 19:19 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-23 20:51 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-24 16:54 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Arno <me@privacy.net> - 2011-07-24 15:29 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-27 11:36 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) The Natural Philosopher <tnp@invalid.invalid> - 2011-07-27 12:13 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) scott@slp53.sl.home (Scott Lurndal) - 2011-07-27 20:48 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-28 10:43 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM> - 2011-07-29 00:49 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Ian Collins <ian-news@hotmail.com> - 2011-07-23 09:44 +1200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-23 10:05 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Paul <nospam@needed.com> - 2011-07-22 20:58 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-23 11:31 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM> - 2011-07-29 01:18 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-23 19:02 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM> - 2011-07-29 01:37 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-23 17:34 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-23 21:25 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-25 08:15 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) scott@slp53.sl.home (Scott Lurndal) - 2011-07-24 23:08 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-25 09:46 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) scott@slp53.sl.home (Scott Lurndal) - 2011-07-25 02:19 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Paul <nospam@needed.com> - 2011-07-24 22:38 -0400
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-25 19:38 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Franc Zabkar <fzabkar@iinternode.on.net> - 2011-07-25 19:34 +1000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Michael Press <rubrum@pacbell.net> - 2011-08-03 21:56 -0700
Re: Help, the dog ate my MBR (Linux/Windows dual boot) John Hasler <jhasler@newsguy.com> - 2011-08-04 08:15 -0500
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM> - 2011-07-29 01:10 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) gordonb.22upl@burditt.org (Gordon Burditt) - 2011-07-23 17:15 -0500
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-07-24 16:42 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-10-27 11:13 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Arno <me@privacy.net> - 2011-10-27 15:24 +0000
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-10-28 11:06 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.COM> - 2011-07-29 00:49 +0100
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Noob <root@127.0.0.1> - 2011-08-01 11:27 +0200
Re: Help, the dog ate my MBR (Linux/Windows dual boot) Nico Kadel-Garcia <nkadel@gmail.com> - 2011-08-06 10:00 -0700
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