On Tue, 2014-04-22 at 12:17 +0100, Arthur Dent wrote:

The reboot put me back into my old F16 install (at least I know that
hasn't been screwed up!) with the grub menu offering me only varying
kernels from F16.

It seems F20 has not installed the bootloader properly.

What are the steps for getting F20 to boot (while, if possible still
giving me the option to boot into F16)?

OK - So now I'm really flummoxed. Here's what I did:
I booted into the F16 install. I ran os-prober which found the new F20
kernel on the other partition (it still listed it below all the F16
ones) and ran grub2-mkconfig -o /boot/grub2/grub.cfg

This allowed me to reboot and see the new F20 install (listed about
half-way down the list of choices on the grub menu). The F16 install is
still the default. I was then able to boot into this
3.11.10-301.fc20.x86_64 kernel. I did a bit of tinkering (pointed /home
to the /home partition etc) and then ran yum update.

This brought in the latest kernel (3.13.10-200.fc20.x86_64). I ran
os-prober and grub2-mkconfig -o /boot/grub2/grub.cfg again. For good
measure I even installed grub-customizer and, sure enough, running that
showed a lovely list with 3.13 at the top, 3.11 beneath it and 3.6 (F16)
below that. My thinking here is that I am booted *into the F20 kernel*
therefore any changes will now be written to /boot *here*.

A save and a reboot and...

Back to the original grub screen...

F16 kernels at the top, the 3.11 F20 kernel below them and NO 3.13
kernel listed!

So when I run grub2-mkconfig -o /boot/grub2/grub.cfg from within the F20
kernel where is it writing to and why isn't the bootloader seeing it?

Any help much appreciated. I can boot into F20 at least now (but not the
latest kernel) but i have to do it manually (the default it still the
F16 kernel).

Thanks

Mark