Comment # 20 on bug 1156441 from Ignaz Forster

(In reply to Michael Chang from comment #18)
> Here the test package for grub2-install to set up $env_block in grubenv
> file, Would you please take some time to test if it works as expected ?
> 
> https://build.opensuse.org/package/show/home:michael-chang:bsc:1156441/grub2

I just rebuilt the images with your modified grub version - everything expected
by this patch is working perfectly fine now:
* The grubenv file is present in the image with the env_block variable set.
* Due to this variables can be set in GRUB also during first boot.
* Modifying the variable with grub2-editenv in the running system still works.

Thanks a lot!

The other ticket is more or less independent of this patch: On read-only
systems it may still be a good idea to be able to write the grub environment
block. To make this possible the idea is to put the grubenv file onto a
separate writable partition. I've currently implemented this using a subvolume
called "/boot/writable", which will be created on read-only systems only,
linking /boot/grub2/grubenv to /boot/writable/grubenv.
This would be working in theory, but unfortunately KIWI deletes any files
called /boot/*/grubenv, so this is not working for our images. On the other
hand the solution is quite hacky (requiring to generate a GRUB script to run
before the 00_header) and creates differences between a read-only and a
read-write system, so I'm not really keen to keep it.
A saner solutions seems to be to make grub2 use a different directory for
grubenv from the beginning and uniformly for all systems (e.g. /boot/var). If
you are not opposed to this I'd just develop a prototype to demonstrate what I
mean.