[gentoo-user] Duel boot - How to verify boot loader updates?

[Mark Knecht]

Hi,
   This is a bit of a conceptual question, simplified but based on a
machine I do own, from someone who knows very little about boot loader
implementations. (I.e. - me) Thanks in advance for any pointers you can
provide.

   Assume a machine with two separate M.2 SSDs. The M.2 devices are
identical in size and from the same manufacturer. For the sake of
discussion they are partitioned identically and they both have the same
distro installed. One is stable, the other is bleeding edge. For simplicity
there are no other disk drives involved in either installation. Both
installs have the same boot loader, grub2 I guess, and both have
configurations that boot themselves by default but offer the other drive as
a second option.

   Assume the bleeding edge system (or the other - it doesn't matter to me)
gets a grub2 update, and further assume the update is either automatic or
done by someone other than yourself. Whoever did the updates 'tests' the
machine by booting into both versions, and both versions are tested as
default in BIOS so that no matter what everything appears to be working.

   THE QUESTION: After the fact, if I wanted to look at the two
installations in detail, how would I determine that the grub update was
done to the installation doing the update and not done to the other
(nearly) identical installation?

Thanks in advance,
Mark