Re: [gentoo-user] UEFI kernel installation?

[Grant Taylor]

On 6/15/19 7:04 AM, Peter Humphrey wrote:
> Hello list,

Hi,

> The main system on this box is ~amd64 plasma, but I also have a
> small rescue system which is amd64, no desktop. I use bootctl from
> systemd-boot to manage the UEFI images.

I don't have much experience with UEFI.  But I do have some thoughts.

> My question is: how much of the bootctl-installed image is essential
> for booting? In other words, if I install the ~amd64 kernel (5.1.9),
> what effect will that have on booting the rescue system; and if
> I install the amd64 kernel (4.19.44), what effect will it have on
> booting the plasma system?

I think it largely depends on where things are installed to.

Do the different installs share a common /boot?  Or do they have 
separate /boot partitions?

I assume the other file systems are separate e.g. / (root), /home.

> In practice, I install the ~amd64 kernel and hope it doesn't affect
> the rescue system too much; and it seems not to. Could I do better?

I don't know if it's better or not, but here's what I'd do.

  · I'd put each OS on it's own drive (if at all possible).
  · I'd have a separate /boot and / (root) for each OS.
  · I'd configure UEFI boot menu entries for each OS.

That way, the only thing that's common between the OSs is the hardware 
and the UEFI.  They are separate from the time that UEFI boot menu onward.

I recommend the separate drives so that you can use the OS on the other 
drive to deal with a drive hardware issue.

I /might/ be compelled to try to leverage the two drives for some swap 
optimization.  I'd probably have a minimal amount of swap on the same 
drive as the OS and more swap on the other drive.  That way each OS has 
some swap in the event that the other drive fails, yet still has more 
swap if the other drive is happy.  So you benefit from the 2nd drive 
without being completely dependent on it.