Isso é por causa do GPT.
No meu sistema Ubuntu 16.04 LTS fdisk -l /dev/sda
mostra o seguinte:
Disk /dev/sda: xxx GiB, yyyyyyyyyyyyy bytes, zzzzzzzzz sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
**Disklabel type: gpt**
Disk identifier: AAAAAAAA-BBBB-CCCC-DDDD-EEEEEEEEEEEE
Device Start End Sectors Size Type
/dev/sda1 2048 616447 614400 300M EFI System
...
Mas sudo parted /dev/sda
mostra quase o mesmo:
(parted) p
Model: ATA ... (scsi)
Disk /dev/sda: xxxGB
Sector size (logical/physical): 512B/512B
**Partition Table: gpt**
Disk Flags:
Number Start End Size File system Name Flags
1 1049kB 316MB 315MB fat32 EFI system partition **boot**, esp
...
Portanto, parted
mostra corretamente o sinalizador boot .