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Re: grub-mkrescue: Problem with MBR partition table at start of EFI part
From: |
Thomas Schmitt |
Subject: |
Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition |
Date: |
Fri, 10 May 2019 09:09:25 +0200 |
Hi,
iwrote:
> What do you get as hex dump of byte 1,062,912 to 1,063,423 ?
I found the answer in the hex dump:
00103800 eb 3c 90 4d 53 44 4f 53 35 2e 30 00 02 01 01 00 |.<.MSDOS5.0.....|
00103810 02 e0 00 40 0b f0 09 00 12 00 02 00 00 00 00 00 |address@hidden|
00103820 00 00 00 00 00 00 29 c0 56 ef 00 45 46 49 53 45 |......).V..EFISE|
00103830 43 54 4f 52 20 20 46 41 54 31 32 20 20 20 fa 33 |CTOR FAT12 .3|
00103840 c0 8e d0 bc 00 7c 16 07 bb 78 00 36 c5 37 1e 56 |.....|...x.6.7.V|
00103850 16 53 bf 3e 7c b9 0b 00 fc f3 a4 06 1f c6 45 fe |.S.>|.........E.|
00103860 0f 8b 0e 18 7c 88 4d f9 89 47 02 c7 07 3e 7c fb |....|.M..G...>|.|
00103870 cd 13 72 79 33 c0 39 06 13 7c 74 08 8b 0e 13 7c |..ry3.9..|t....||
00103880 89 0e 20 7c a0 10 7c f7 26 16 7c 03 06 1c 7c 13 |.. |..|.&.|...|.|
00103890 16 1e 7c 03 06 0e 7c 83 d2 00 a3 50 7c 89 16 52 |..|...|....P|..R|
001038a0 7c a3 49 7c 89 16 4b 7c b8 20 00 f7 26 11 7c 8b ||.I|..K|. ..&.|.|
001038b0 1e 0b 7c 03 c3 48 f7 f3 01 06 49 7c 83 16 4b 7c |..|..H....I|..K||
001038c0 00 bb 00 05 8b 16 52 7c a1 50 7c e8 92 00 72 1d |......R|.P|...r.|
001038d0 b0 01 e8 ac 00 72 16 8b fb b9 0b 00 be e6 7d f3 |.....r........}.|
001038e0 a6 75 0a 8d 7f 20 b9 0b 00 f3 a6 74 18 be 9e 7d |.u... .....t...}|
001038f0 e8 5f 00 33 c0 cd 16 5e 1f 8f 04 8f 44 02 cd 19 |._.3...^....D...|
00103900 58 58 58 eb e8 8b 47 1a 48 48 8a 1e 0d 7c 32 ff |XXX...G.HH...|2.|
00103910 f7 e3 03 06 49 7c 13 16 4b 7c bb 00 07 b9 03 00 |....I|..K|......|
00103920 50 52 51 e8 3a 00 72 d8 b0 01 e8 54 00 59 5a 58 |PRQ.:.r....T.YZX|
00103930 72 bb 05 01 00 83 d2 00 03 1e 0b 7c e2 e2 8a 2e |r..........|....|
00103940 15 7c 8a 16 24 7c 8b 1e 49 7c a1 4b 7c ea 00 00 |.|..$|..I|.K|...|
00103950 70 00 ac 0a c0 74 29 b4 0e bb 07 00 cd 10 eb f2 |p....t).........|
00103960 3b 16 18 7c 73 19 f7 36 18 7c fe c2 88 16 4f 7c |;..|s..6.|....O||
00103970 33 d2 f7 36 1a 7c 88 16 25 7c a3 4d 7c f8 c3 f9 |3..6.|..%|.M|...|
00103980 c3 b4 02 8b 16 4d 7c b1 06 d2 e6 0a 36 4f 7c 8b |.....M|.....6O|.|
00103990 ca 86 e9 8a 16 24 7c 8a 36 25 7c cd 13 c3 0d 0a |.....$|.6%|.....|
001039a0 4e 6f 6e 2d 53 79 73 74 65 6d 20 64 69 73 6b 20 |Non-System disk |
001039b0 6f 72 20 64 69 73 6b 20 65 72 72 6f 72 0d 0a 52 |or disk error..R|
001039c0 65 70 6c 61 63 65 20 61 6e 64 20 70 72 65 73 73 |eplace and press|
001039d0 20 61 6e 79 20 6b 65 79 20 77 68 65 6e 20 72 65 | any key when re|
001039e0 61 64 79 0d 0a 00 49 4f 20 20 20 20 20 20 53 59 |ady...IO SY|
001039f0 53 4d 53 44 4f 53 20 20 20 53 59 53 00 00 55 aa |SMSDOS SYS..U.|
An MBR signature 55 aa. But cleartext where the partition table should be.
If Microsoft ISOs shall really be considered standard, then any kind of
garbage is ok in a potential partition table at the start of the EFI
partition.
The firmware of the affected Macbook probably tolerates everything
except four zeros at byte offset 454 (here: 0x1039c6), where Microsoft
has 20 61 6e 64.
(It feels like two cars speeding on a salt lake. Probability for collision
is low. Just close your eyes and trust in your luck.)
Have a nice day :)
Thomas
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/01
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Chris Murphy, 2019/05/09
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/09
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/10
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition,
Thomas Schmitt <=
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, pelzflorian (Florian Pelz), 2019/05/10
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/10
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, pelzflorian (Florian Pelz), 2019/05/10
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/10
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, pelzflorian (Florian Pelz), 2019/05/11
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/11
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, pelzflorian (Florian Pelz), 2019/05/11
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/11
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, pelzflorian (Florian Pelz), 2019/05/11
- Re: grub-mkrescue: Problem with MBR partition table at start of EFI partition, Thomas Schmitt, 2019/05/11