GRUB fallback on boot failure

GRUB fallback on boot failure

[Nathan Dehnel]

Is it possible in guix to try to boot the latest generation and then
go down the list of previous generations and try to boot them until
one of them works? My understanding is this is done by adding the
following to /etc/default/grub:

export GRUB_FALLBACK="1 2...{number of entries}"
GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true

Re: GRUB fallback on boot failure

[Felix Lechner via]

Hi Nathan,

On Sat, May 27, 2023 at 3:52 PM Nathan Dehnel <ncdehnel@gmail.com> wrote:
>
> My understanding is this is done by adding the
> following to /etc/default/grub:
>
> export GRUB_FALLBACK="1 2...{number of entries}"
> GRUB_DEFAULT=saved
> GRUB_SAVEDEFAULT=true

I believe it will work, but booting older GRUB entries in Guix comes
with a distinct inconvenience. To my knowledge, it is difficult to
tell in which iteration you are once you have booted.

Ideally, you would merely "roll back" to the system iteration you
identified as stable. Then the generation that 'guix system
list-generations' shows as (current) corresponds to the system you are
in, and grub.cfg will be rewritten to put that iteration on top. In
that workflow, there is no need to touch the default.

Personally, I think it's easier to maintain (and update) but please
feel free to experiment to find out what works best for you.

Kind regards
Felix

Re: GRUB fallback on boot failure

[Nathan Dehnel]

>I believe it will work
The problem is I didn't see any documented way to write verbatim to
/etc/default/grub from the service, so I'm wondering if I need to
write a feature request

>Ideally, you would merely "roll back" to the system iteration you
identified as stable. Then the generation that 'guix system
list-generations' shows as (current) corresponds to the system you are
in, and grub.cfg will be rewritten to put that iteration on top. In
that workflow, there is no need to touch the default.
Is it possible to do this without user interaction in the event of a
failure to boot?

On Mon, May 29, 2023 at 6:29 PM Felix Lechner
<felix.lechner@lease-up.com> wrote:
>
> Hi Nathan,
>
> On Sat, May 27, 2023 at 3:52 PM Nathan Dehnel <ncdehnel@gmail.com> wrote:
> >
> > My understanding is this is done by adding the
> > following to /etc/default/grub:
> >
> > export GRUB_FALLBACK="1 2...{number of entries}"
> > GRUB_DEFAULT=saved
> > GRUB_SAVEDEFAULT=true
>
> I believe it will work, but booting older GRUB entries in Guix comes
> with a distinct inconvenience. To my knowledge, it is difficult to
> tell in which iteration you are once you have booted.
>
> Ideally, you would merely "roll back" to the system iteration you
> identified as stable. Then the generation that 'guix system
> list-generations' shows as (current) corresponds to the system you are
> in, and grub.cfg will be rewritten to put that iteration on top. In
> that workflow, there is no need to touch the default.
>
> Personally, I think it's easier to maintain (and update) but please
> feel free to experiment to find out what works best for you.
>
> Kind regards
> Felix