Bug in Ubuntu Installer?

Question

if I install Ubuntu (12.10 64 Bit) on a MBR formatted hard disk, based on a EFI system, I should get the partition type 0xEF for the EFI System partition but instead I retrieve 0x0B what stands for a FAT32 formatted volume. The system is working anyway but I spent a lot of time with that.

# dd if=/dev/sda bs=512 count=1 | hexdump -C
00000000  fa b8 00 10 8e d0 bc 00  b0 b8 00 00 8e d8 8e c0  
00000010  fb be 00 7c bf 00 06 b9  00 02 f3 a4 ea 21 06 00  
00000020  00 be be 07 38 04 75 0b  83 c6 10 81 fe fe 07 75  
00000030  f3 eb 16 b4 02 b0 01 bb  00 7c b2 80 8a 74 01 8b  
00000040  4c 02 cd 13 ea 00 7c 00  00 eb fe 00 00 00 00 00  
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
*
000001b0  00 00 00 00 00 00 00 00  6e f9 08 00 00 00 80 20 
000001c0  21 00 0b 1c 10 0c 00 08  00 00 00 f0 02 00 00 1c  
000001d0  11 0c 83 ad 31 3c 00 f8  02 00 00 e8 0b 00 00 ad  
000001e0  32 3c 82 d6 05 91 00 e0  0e 00 00 e0 14 00 00 f6  
000001f0  24 91 05 fe ff ff fe c7  23 00 02 30 1c 01 55 aa

So my question is if this is a bug of the installer or at least an undocumented feature but basically it's not correct...

Thx & Bye Tom

Answer 1

The libparted library, upon which Ubuntu's installer is based, has no way to flag an MBR partition as being an EFI System Partition (ESP). On GPT disks, this is done by setting the "boot flag" on the partition, but this action on an MBR disk has a different effect: It sets the boot flag. This is a design flaw in libparted; they've overloaded the same term on entirely different concepts for GPT and MBR disks.

You can fix the problem using the fdisk, cfdisk, or sfdisk programs in Linux. Use the t command to change the type code from 0x0B to 0xEF, then save your changes with w.