Subj : Updating grub boot order w/out update-grub?
To   : All
From : Dumas Walker
Date : Sun Sep 22 2019 02:22 pm

I have a headless sbc.  It cannot be made not headless (i.e. there is no HDMI
port on the damn thing).  In order to try to get synchronet to compile on it, I
had to update g++ which somehow meant I needed a new kernel.

So, long story short of course it lead to a kernel panic (or something that I
cannot access the board to see).  Used to be I could just take the sd card out,
change the grub configuration to point back to the old kernel and get access to
the board again.  

However, some dumbass programmer decided at some point that we need to use a
new and improved grub and the only way to update anything is to edit the config
and then you have to run a program to actually apply the update because that is
somehow better than having only one step to do it.

OK all fine and dandy but I don't think running that update program on my
laptop is going to cause the grub config on the sd card for the sbc to actually
be updated.  

So is there a way to get the grub on the sd card updated from another machine
so that the sbc will boot again?  I am thinking maybe I can rename the vmlinuz
and initrd images in the /boot directory (to back them up) for the version that
won't boot, and then create symlinks named after them that point to the old
versions instead.  That is the only think I have come up with so far but have
not tried it yet.  :(

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