Re: Grub, sparc64, and compressed kernels

[Chris Ross <cross+debian@distal.com>]

On Tue, Jul 03, 2018 at 03:24:12PM -0400, Chris Ross wrote:
> Okay.  So, in prepping a chroot'd md/zfs environemnt on this machine, while
> updating the kernel packages, I see:
> 
> /etc/kernel/postinst.d/zz-update-grub:
> Generating grub configuration file ...
> Found linux image: /boot/vmlinuz-4.16.0-2-sparc64-smp
> Found initrd image: /boot/initrd.img-4.16.0-2-sparc64-smp
> /usr/sbin/grub-probe: error: disk `md0' not found.
> /usr/sbin/grub-probe: error: disk `md0' not found.
> /usr/sbin/grub-probe: error: disk `md0' not found.
> Found linux image: /boot/vmlinuz-4.16.0-1-sparc64-smp
> Found initrd image: /boot/initrd.img-4.16.0-1-sparc64-smp
> /usr/sbin/grub-probe: error: disk `md0' not found.
> /usr/sbin/grub-probe: error: disk `md0' not found.
> Found Debian GNU/Linux buster/sid on /dev/sdd2
> done
> 
> This leads me to the same problem I had earlier, grub (grub-probe or
> grub-install) saying "error: disk `md0' not found."  I think this is why
> I started down a path of looking for an alternative grub2.

Sorry, stupid user trick.  I had mdadm and friends in the disk I was running
on, but had _not_ installed those packages into the environment in md/ZFS
that I chrooted into.  After installing mdadm (and the collection it brought),
I am able to update-grub.  And grub-probe gives me the answer I'd expect:

(chroot) root@t5120# grub-probe -d /dev/md0
ext2

But, I'm seeing the following if I try to grub-install:

(chroot) root@t5120# grub-install --force --skip-fs-probe /dev/md0
Installing for sparc64-ieee1275 platform.
grub-install: warning: File system `ext2' doesn't support embedding.
grub-install: warning: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and their use is discouraged..
zsh: segmentation fault  grub-install --force --skip-fs-probe /dev/md0

(1) Is this supposed to work?
(2) Assuming it's not actually installed correctly yet, booting will fail.
    Should I grub-install onto /dev/sda1 or /dev/sda2?  Whether one or both,
    won't that mess up the RAID of those devices?

                       - Chris