Someone wrote in [personal profile] mjg59 2012-05-05 11:25 am (UTC)

Do i get it right that the EFI VFAT image may also be booted by non-Macs ?
(What other machines do not work with MBR isohybrid alone ?)

I am working my way through the Apple partitions of Fedora-LiveCD.iso
and perceive inconsistencies about the block size:

- The starting sector of map entry 1 (byte 0x080b) is 1.
So this is given in blocks of 2048.

- The partition size of map entry 1 is 16 (byte 0x080f).
This can hardly be blocks of 2048, because then it would claim the
ISO 9660 superblock as part of the Apple partition map.

- In map entry 2, the starting sector (byte 0x100b) is 41, which matches
the ISO 9660 block address of /isolinux/efiboot.img.
So this must be blocks of 2048.

- In map entry 2, the partition size is 1136 which is 4 times the number
of ISO 9660 blocks of /isolinux/efiboot.img = 284.
So this must be blocks of 512.

Further riddles:

- Map entry 2 points to the block address of /isolinux/efiboot.img but
has as partition type "Apple_HFS". To program "file" it looks like
"FAT (12 bit)".

- The "logical block count" resp. "size of data area" in byte 0x0857 is 10.
Shouldn't it have the same value as "size of partition in sectors" (byte
0x080f) ?
In map entry 2, the two numbers match (both as blocks of 512).

Additionally to your link, i found this URL helpful as reference:
http://opensource.apple.com/source/IOStorageFamily/IOStorageFamily-116/IOApplePartitionScheme.h

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