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I installed Kubuntu on a Macbook Pro 8,2 and am trying to get it from legacy to EFI boot.

Kubuntu forced me to create an "efiboot partition of at least 1 MiB" (fs id 'ee').

Thats just the successor of the MBR in disguise, isn't it?

In the tutorials for grub-efi-amd64, there's always references to the "EFI partition", a FAT16 of at least 200 MiB.

This is independent of the first one and has to be created, right? I could shrink my home-partition and append this as sda5, or is it critical, where the partition is located?

migrated from serverfault.com Apr 28 '13 at 18:32

This question came from our site for system and network administrators.

  • No, an EFI System Partition is an EFI System Partition. There should be no different usages of that term since there can only be one partition of that type on a physical drive. Usually a UEFI system is setup with a GUID partition table but Apple hardware may be completely different in this term. I recommend following instructions for setting up Ubuntu on Apple hardware in the Wiki, those should provide correct information. – LiveWireBT Apr 29 '13 at 2:24
  • Yeah, I read the (U)EFI booting in the ubuntu help wiki, but since this entry tells me to compile grub-efi 1.99 by hand whereas grub-efi is now a ready-to-go package, that site is someout outdated. – arney Apr 30 '13 at 16:12
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I suspect that you're seeing, and confusing, three different things:

  • The GUID Partition Table (GPT) scheme includes a "protective MBR," which is a Master Boot Record (MBR) partition table that contains a single partition, of type 0xEE, that spans (more-or-less) the entire disk, from sector 1 to either the end of the disk or the 2GiB point (assuming 512-byte sectors), whichever is less. The 0xEE partition is often called the "protective partition." This has nothing to do with an "EFI partition," "BIOS boot partition," or any other GPT partition, except to the extent that the protective MBR is a necessary component of a complete GPT configuration. The protective partition isn't really a partition, either; it exists just to keep GPT-unaware utilities from messing with the disk.
  • On a computer that boots in EFI mode, an EFI System Partition (ESP) is required. This partition uses a FAT32 filesystem (FAT16 can usually work in practice, but the spec requires FAT32) and holds EFI boot loaders and related files. When the computer boots, the EFI reads boot loaders from the ESP. Its size is not defined by the spec, but in practice it's usually around 100-200MiB. I recommend creating a bigger ESP, in the range of 550MiB, because some EFIs seem to have buggy FAT drivers that cause problems with smaller ESPs.
  • If you install GRUB in BIOS mode to a GPT disk, it will be happiest if the disk contains a BIOS Boot Partition. This partition is typically 1MiB or 2MiB in size, and it holds the second stage of GRUB's boot code (the first stage goes in the MBR's code area). This partition is not required when booting a computer in EFI mode.

The ESP and BIOS Boot Partition can both go just about anywhere, at least in theory, although on an over-2GiB disk, it's best to keep the BIOS Boot Partition under the 2GiB mark.

  • Alright, this is very tight. Just minor detail: In my intuition, a partition table should not show up as /dev/sda1. And since I was asked to create this very partition in a size of at least 1 MiB, I guess that is my Bios Boot Partition. So I guess I should get a 1GiB FAT partition somewhere at the beginning of the disk ... and after EFI booting runs, I could just ignore the Bios Boot Partition. – arney Apr 30 '13 at 16:32
  • The partition table does not show up as /dev/sda1. Under Linux with /dev/sda holding a GPT, /dev/sda1 will be the first GPT partition. That could be a BIOS Boot Partition, an ESP, or something else. It will not be the MBR's protective partition, though -- that doesn't get a partition identifier under Linux. The protective partition will show up in an fdisk scan of the disk, though, since fdisk doesn't (yet) understand GPT. – Rod Smith Apr 30 '13 at 16:38
  • Ah, might it be, that fdisk reads the GPT, recognizes it as 0xEE, reads further to the Bios Boot Partition, and hence I see /dev/sda1 as 0xEE - a mere coincidence of one preceeding the other? – arney Apr 30 '13 at 16:53
  • A, I just learned about parted and sda1 is listed there as having no filesystem, but flagged as bios_grub, so my conjecture seems right. see also – arney Apr 30 '13 at 17:22
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http://en.wikipedia.org/wiki/GUID_Partition_Table

"On a disk having 512-byte sectors, a partition entry array size of 16,384 bytes and the minimum size of 128 bytes for each partition entry, LBA 34 is the first usable sector on the disk."

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    Would you mind explaining how this relates to the question? – arney Apr 28 '13 at 16:32
  • Welcome to Server Fault! Generally we like answers on the site to be able to stand on their own - Links are great, but if that link ever breaks the answer should have enough information to still be helpful. Please consider editing your answer to include more detail. See the FAQ for more info. – slm Apr 28 '13 at 16:44
  • I think he won't elaborate further on that, since a question about installing Kubuntu on a laptop doesn't relate to serverfault.com. – LiveWireBT Apr 29 '13 at 3:03
  • Sorry LiveWireBT, I considered it a hardware question - especially since I posted a question about grub-efi here and no one bothered to answer. – arney Apr 30 '13 at 16:18

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