boot - The MBR of the Ubuntu ISO has partition type 0, which is an invalid value - Ask Ubuntu
this question has answer here:
the following line shows the 4 partition table entries of 16 bytes each. see here specification of format.
$ sudo hd ubuntu-16.10-desktop-amd64.iso -s 446 -n 64 000001be 80 00 01 00 00 5e e0 ff 00 00 00 00 00 80 2f 00 |.....^......../.| 000001ce 00 fe ff ff ef fe ff ff 54 24 2f 00 c0 12 00 00 |........t$/.....| 000001de 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 000001fe the latter 3 zeros, while first entry interesting one. byte 0 (counting 0) has value 0x80 means in fact describe "an active partition". byte 4 describes partition type, fx 0x0b fat32. 0 invalid value. according this source:
00 : -- should not used in actual table entry! not indicate unknown type, rather empty entry; in case, other fields in 16-byte entry should zero-filled well.
so according can read, mbr data invalid. going on?
i did ubuntu 16.04 (yakkety), downloaded via this link, , file has md5sum 3f50877c05121f7fd8544bef2d722824.
i don't have idea partition systems, believe reason it's not plain mbr filesystem. using parted:
$ parted ubuntu-16.10-desktop-amd64.iso p warning: driver descriptor says physical block size 2048 bytes, linux says 512 bytes. ignore/cancel? ignore model: (file) disk /home/muru/ubuntu-16.10-desktop-amd64.iso: 6375mb sector size (logical/physical): 2048b/512b partition table: mac disk flags: number start end size file system name flags 1 2048b 6143b 4096b apple 2 1582mb 1584mb 2458kb efi note: partition table: mac. , wikipedia article apple partition map says:
some hybrid discs contain both iso 9660 primary volume descriptor , apple partition map, allowing disc work on different types of computers, including apple systems.
i don't know why parted thinks file 6gb in size, though. however, file agrees there's involving apple partition map here:
$ file ubuntu-16.10-desktop-amd64.iso -k | fold -w 80 ubuntu-16.10-desktop-amd64.iso: dos/mbr boot sector iso 9660 cd-rom filesystem d ata (dos/mbr boot sector) 'ubuntu 16.10 amd64' (bootable); partition 2 : id=0xef , start-chs (0x3ff,254,63), end-chs (0x3ff,254,63), startsector 3089492, 4800 se ctors dos/mbr boot sector iso 9660 cd-rom filesystem data (dos/mbr boot sector) 'ubuntu 16.10 amd64' (bootable) apple driver map, blocksize 2048, blockcount 370 08, devtype 0, devid 0, descriptors 0, contains[@0x800]: apple partition map, ma p block count 2, start block 1, block count 2, name apple, type apple_partition_ map iso 9660 cd-rom filesystem data, contains[@0x1000]: apple partition map, map block count 2, start block 772373, block count 1200, name efi, type apple_hfs 9660 cd-rom filesystem data, contains[@0x1800]: iso 9660 cd-rom filesystem da ta foxpro fpt, blocks size 37008, next free block index 1163003904\012- data
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