Re: How to mount a "BIOS boot partition"?

[Giovanni Gherdovich]

On Sat, Oct 1, 2016 at 12:51 AM, Xen <address@hidden> wrote:
> Giovanni Gherdovich schreef op 30-09-2016 20:25:
>>
>> Hello,
>>
>> I'd like to install two different linux distributions and use grub to
>> boot into one or the other. I have a dedicated grub partition on
>> /dev/sda1 and two other partitions for the OSes. /dev/sda1 appears to
>> be a "BIOS boot partition" to tools like parted(8), fdisk(8) or
>> gdisk(8).
>
>
> As far as I know the "BIOS Boot Partition" does not contain any filesystem
> but only the Grub image. It is the space you need that would otherwise be
> put somewhere between the MBR and the first partition.
>
> I think you do not need to run grub2-install on /dev/sda1, but on /dev/sda,
> though, and it will pick the boot partition automatically(?).
>
> Your boot directory is just going to be on any regular filesystem that you
> have access to. In your case that is /dev/sda4, apparently.
>
> So I think you simply need to be installing on /dev/sda.
>
> In case you want to move your boot files off of /dev/sda4, you could split
> /dev/sda1 (it doesn't need to be 500MB, 1 or 2MB would be fine).
>
> So you would delete it, create a new first partition of /dev/sda1, then
> another dedicated boot partition /dev/sda2 (you can use a tool like parted
> to renumber your gpt partitions) and then your remaining partitions will
> shift until /dev/sda5, you will now have 5 partitions, including one new
> "regular boot partition" containing an actual filesystem (like ext2).
>
> Regards.

Thanks, that worked like a charm.

I did exactly what you suggested (I used gdisk to manipulate the partitions).
After that I went with

   grub2-install --boot-directory=/mnt/boot /dev/sda

and it just did the right thing: put the core.img file on the filesystem-less
"bios boot partition", which it found on its own; core.img then was pointing
to a grub2 binary located in /mnt/boot, i.e. the mount point of my newly created
ext2 regular boot partition.

Giovanni