rebooting with new kernel

[Chris Murphy]

On Sun, Jul 12, 2015 at 4:43 AM, Paul Cartwright <pbcartwright at gmail.com> wrote:
> I did a dnf update, got the new kernel,
> uname -a
> Linux pauls-server 4.0.7-300.fc22.x86_64 #1 SMP Mon Jun 29 22:15:06 UTC
> 2015 x86_64 x86_64 x86_64 GNU/Linux
>
>
> rebooted and... a blinking cursor on a black background..
> this seems to happen everytime now when I get a new kernel in F22,
> x86_64. So I boot a boot-repair CD, redo the grub, and reboot with a
> grub menu.
> my F22 is /dev/sdb6, and when I do a grub2-mkconfig it finds all of my
> OSes on sda & sdb. once I manually do the grub2-mkconfig & grub2-install
> /dev/sda I can reboot & grub shows all of my OSes. But if I just do the
> dnf update, get a new kernel, and reboot.. blank. Not sure what the
> update does, but it obviously takes out my grub install, not sure what
> it replaces it with. what should I look for, or what am I doing wrong?

Chances are it's a bug. All you did was accept and update, and then
the update broke boot.

At the GRUB menu instead of waiting for the timeout or hitting return
on the default option, hit e to edit the entry, find the linux16 or
linuxefi line, go to the end and remove quiet rhgb, and then F10 or
Control-X to boot and see if you get some messages that make it more
clear what's going on. From the description I can't even tell if the
problem is a GRUB failure or a kernel or initramfs failure.

A kernel update runs grubby which modifies grub.cfg. There is nothing
that grubby does that grub2-install would fix. Whereas grub2-mkconfig
obliterates the grubby modified grub.cfg, and writes a new one from
scratch in its place.

-- 
Chris Murphy