[arch-general] Reboot - Versioned Kernel Installs

[Timothy L.]

On Thu, Jun 9, 2011 at 9:25 PM, C Anthony Risinger <anthony at xtfx.me> wrote:

> On Jun 9, 2011 5:50 PM, "Heiko Baums" <lists at baums-on-web.de> wrote:
> > Am Thu, 9 Jun 2011 17:36:21 -0500
> > schrieb C Anthony Risinger <anthony at xtfx.me>:
> >
> >> does this sound genius or completely insane? some insanely genius guy
> >> once said they are only separated by a fine line ...
> >
> > Sounds completely insane.
>
> ooooook ... and ... why?
>
> ) initramfs is not very big (fallback on my sys is only 13MB + 2MB kern)
> ) keeps the whole thing in mkinitcpio
> ) does not affect any current images and is even backward compat
> ) small chance of absolute failure (i think :-)
> ) only small changes to mkinitcpio, if any at all
> ) ...
> ) ... KISS BABY!
> ) oh yeah and ... PROFIT!
>
> im pretty sure it could be implemented as a hook (possibly 2) to the
> current system ... this might even be the best way.  `install` hook
> would unpack the current image to a known location (prob
> `/lib/initcpio` somewhere), copy the kernel to the same place, and
> then add the directory to the image (after removing the old-old image
> if existed :-).  the real `hook` would then check for one of two
> flags:
>
> ) kexec.flag ... kexec the old kernel with the boot.flag
> ) boot.flag ... chroot to "previous", run old hooks/mods/etc, exit
> chroot, switch_root like normal
>
> i thought it was pretty succinct ... elegant even :-)  ... with some
> sprinkles of insanity that give it the funny but mildly enjoyable
> aftertaste.  i don't have any free time for a couple days, but i'm
> *pretty* sure this could be done as a hook to the current mkinitcpio
> in a couple hours -- might take a whack at it this weekend, would be
> useful, as i've personally mucked my boot more than once, and though i
> can recover easily enough, i'm liking this more and more ...
>
> ... though i could very well be missing something obvious, certainly
> wouldn't be the first time ... surely someone out there reads this and
> thinks "why not?"
>
> C Anthony
>


Keeping the previous kernel after upgrading sounds sane to me. For the
apprehensive, couldn't we just include a simple configuration option/check
somewhere?

/etc/mkinitcpio.conf
KEEP_PREVIOUS_KERNEL="yes"

I've read most of this thread but please excuse me if this has already been
mentioned.