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> Date: Sun, 7 Jun 2015 23:23:26 -0400
> From: garydale@torfree.net
>
>>
>> On top of that, grub installs its stage2 bootloader in the unclaimed
>> space between the MBR and the first partition. That space is not unused
>> in the GPT disk format, so when you simply convert your existing
>> partitions, grub will have no place to install its stage2 and
>> grub-install will error out. To have grub-pc boot from a GPT disk, you
>> need to have a Bios Boot Partition (gdisk partition type ef02) of at
>> least 128kB.
> I added one early on in the process. It's 100M which should be plenty. I
> later formatted it as FAT32 after reading that it need that, but it
> didn't help.
There's still some confusion here:
- The ESP (Efi System Partition) is recommended to be around 100-200MB
and should be formatted as FAT32. Its partition type in gdisk should
be EF00, and it should be mounted on /boot/efi. It is required to be
present when using EFI boot.
- The BBP (Bios Boot Partition) is only needed to store grub's second-
stage loader and doesn't need to be any larger than 1MB. It should
not be formatted or mounted, as grub will use the raw space. Its
partition type in gdisk is EF02. It is only needed when using grub
to bios-boot from a GPT disk.
>>
>> Luckily, most partition tools start their first partition at the 1MB
>> boundary, so you can usually create that bios boot partition between
>> sectors 40 and 2048, but that's not a given.
> The original Windows layout had a recovery partition starting at 2048
> and the main Windows partition coming after that. There wasn't an EFI
> partition on the original layout. Nor did I add one when I shrank the
> main partition and installed Linux. I only added an EFI partition after
> switching to GPT.
If there wasn't an EFI System Partition, you were not booting through
UEFI but in BIOS mode (which we already knew, as Windows does not
support booting in EFI mode from an MBR-style disk). I can't explain
how grub-efi came to be on your system, but it wasn't what made your
system boot.
Regards,
Arno
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