On Jun 11, 2007, at 12:52 PM, Rui Paulo wrote:
A typical Intel Mac system using GPT ought to look something like
this:
# fdisk /dev/rdisk0
Disk: /dev/rdisk0 geometry: 9964/255/63 [160086528 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
---------------------------------------------------------------------
---
1: EE 1023 254 63 - 1023 254 63 [ 1 - 160086520]
<Unknown ID>
2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
# gpt -r show /dev/rdisk0
start size index contents
0 1 PMBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-
xxxxxxxxxxxx
409640 159414704 2 GPT part - 48465300-0000-11AA-AA11-
xxxxxxxxxxxx
159824344 262151
160086495 32 Sec GPT table
160086527 1 Sec GPT header
Well, what's happening is that Boot Camp syncs the BIOS partition
table with the GPT table, so the first partition should start at 40,
just like the GPT.
Why does it start at 40 ? Because you need room for the PMBR, the
Primary GPT header and the Primary GPT table.
Agreed, you need about 32 sectors for the GPT header+table.
Now, you don't seem to have used Boot Camp on your Mac, right?
It's true that the machine in question has never used BootCamp, correct.
If you ever use it, fdisk /dev/rdisk0 will show things differently.
The first partition with id 0xEE will should start at LBA 40 and end
at LBA 409640.
OK: although that surprises me a bit, perhaps trying to get Windows
XP (which may not understand the ~32 sector GPT header+table) means
that claiming the first partition in the MBR starts at 40 works
better...?
The first, small partition is almost certainly a "boothfs" boot
partition, as described in the man page for Apple's version of
fdisk:
I don't think so.
The boothfs partition doesn't seem to be used on Intel Macs no
longer. The EFI boot loader that comes with Intel Macs can read HFS+
without any help (actually it's an EFI module), so bootufs/boothfs
partitions are no longer required.
It looks like you're right-- the OS-X formatting utilities still
reserve space for the boot partition, but they just scribble enough
to this space to indicate that the partition isn't actually bootable:
# dd if=/dev/disk0s1 bs=512 count=409600 | hexdump -C
00000000 eb 58 90 42 53 44 20 20 34 2e 34 00 02 01 20 00 |.X.BSD
4.4... .|
00000010 02 00 00 00 00 f0 00 00 00 00 00 00 28 00 00 00
|............(...|
00000020 00 40 06 00 67 0c 00 00 00 00 00 00 02 00 00 00
|[EMAIL PROTECTED]|
00000030 01 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
00000040 00 00 29 f4 11 60 28 45 46 49 20 20 20 20 20 20 |..)..`
(EFI |
00000050 20 20 46 41 54 33 32 20 20 20 fa 31 c0 8e d0 bc |
FAT32 .1....|
00000060 00 7c fb 8e d8 e8 00 00 5e 83 c6 19 bb 07 00 fc
|.|......^.......|
00000070 ac 84 c0 74 06 b4 0e cd 10 eb f5 30 e4 cd 16 cd
|...t.......0....|
00000080 19 0d 0a 4e 6f 6e 2d 73 79 73 74 65 6d 20 64 69 |...Non-
system di|
00000090 73 6b 0d 0a 50 72 65 73 73 20 61 6e 79 20 6b 65 |
sk..Press any ke|
000000a0 79 20 74 6f 20 72 65 62 6f 6f 74 0d 0a 00 00 00 |y to
reboot.....|
000000b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa
|..............U.|
00000200 52 52 61 41 00 00 00 00 00 00 00 00 00 00 00 00 |
RRaA............|
00000210 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
000003e0 00 00 00 00 72 72 41 61 ff ff ff ff ff ff ff ff
|....rrAa........|
000003f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa
|..............U.|
00000400 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
00000c00 eb 58 90 42 53 44 20 20 34 2e 34 00 02 01 20 00 |.X.BSD
4.4... .|
00000c10 02 00 00 00 00 f0 00 00 00 00 00 00 28 00 00 00
|............(...|
00000c20 00 40 06 00 67 0c 00 00 00 00 00 00 02 00 00 00
|[EMAIL PROTECTED]|
00000c30 01 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
00000c40 00 00 29 f4 11 60 28 45 46 49 20 20 20 20 20 20 |..)..`
(EFI |
00000c50 20 20 46 41 54 33 32 20 20 20 fa 31 c0 8e d0 bc |
FAT32 .1....|
00000c60 00 7c fb 8e d8 e8 00 00 5e 83 c6 19 bb 07 00 fc
|.|......^.......|
00000c70 ac 84 c0 74 06 b4 0e cd 10 eb f5 30 e4 cd 16 cd
|...t.......0....|
00000c80 19 0d 0a 4e 6f 6e 2d 73 79 73 74 65 6d 20 64 69 |...Non-
system di|
00000c90 73 6b 0d 0a 50 72 65 73 73 20 61 6e 79 20 6b 65 |
sk..Press any ke|
00000ca0 79 20 74 6f 20 72 65 62 6f 6f 74 0d 0a 00 00 00 |y to
reboot.....|
00000cb0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
00000df0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa
|..............U.|
00000e00 52 52 61 41 00 00 00 00 00 00 00 00 00 00 00 00 |
RRaA............|
00000e10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
00000fe0 00 00 00 00 72 72 41 61 ff ff ff ff ff ff ff ff
|....rrAa........|
00000ff0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa
|..............U.|
00001000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
00004000 f0 ff ff 0f ff ff ff 0f ff ff ff 0f 00 00 00 00
|................|
00004010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
00190e00 f0 ff ff 0f ff ff ff 0f ff ff ff 0f 00 00 00 00
|................|
00190e10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
0031dc00 45 46 49 20 20 20 20 20 20 20 20 08 00 00 00 00 |
EFI .....|
0031dc10 00 00 00 00 00 00 1b a7 85 35 00 00 00 00 00 00 |.........
5......|
0031dc20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
|................|
*
409600+0 records in
409600+0 records out
--
-Chuck
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