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Re: grub + GPT BIOS boot partition
From: |
Andrei Borzenkov |
Subject: |
Re: grub + GPT BIOS boot partition |
Date: |
Sat, 4 Oct 2014 22:56:37 +0400 |
В Sat, 4 Oct 2014 17:39:38 +0000
"Boylan, Ross" <address@hidden> пишет:
> The manual (3.4) says, for GPT and the BIOS boot partition
> "With partitioning programs that require setting the GUID directly, it should
> be ‘21686148-6449-6e6f-744e656564454649’.
>
> Caution: Be very careful which partition you select! When GRUB finds a BIOS
> Boot Partition during installation, it will automatically overwrite part of
> it. "
>
> Does this mean that the installer will overwrite the BIOS Boot partition on
> every disk that has one (since they all have the same GUID), or only on the
> target disk?
Only on target disk.
> Giving the same
> GUID to different partitions seems like a recipe for
trouble. Or is the GUID some type flag in GPT and not the partition
UUID?
>
It is partition type.
> What happens with a GPT disk that does not have a BIOS boot partition?
>
grub-install will refuse to install grub2 on while disk (/dev/sda as
example).
> I'm also a little confused about the role of the BIOS boot partition vs /boot
> for Linux systems. I thought the installer wrote itself into /boot. Is it
> that some of the key components also go in BIOS boot so that grub knows
> enough to be able to read /boot?
>
Yes, this is core.img which contains enough code to be able to read
remaining of grub from /boot.
MBR traditionally had empty space before first partition which is used
to store bootloader. GPT has nothing like it, so bios_grub partition is
used to reserve space on disk to ensure it won't be allocated to
another partition.
> Thanks.
> Ross Boylan
>
> cc's appreciated.
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