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From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Seeking guidance regarding system roll-back and switch-generation
Date: Mon, 25 Jul 2016 10:06:32 +0200
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To: Chris Marusich <cmmarusich@gmail.com>
Cc: guix-devel@gnu.org

Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

>> The output of =E2=80=98guix system build=E2=80=99 contains the =E2=80=98=
parameters=E2=80=99 file, which
>> is enough to generate grub.cfg (see =E2=80=98previous-grub-entries=E2=80=
=99 in (guix
>> scripts system)).
>
> What if someone specifies extra "menu-entries" in their operating system
> configuration file?  (as described in "(guix) GRUB Configuration")?
> Those extra entries don't appear to be stored in the parameters file.

They=E2=80=99re not stored there, but that=E2=80=99s fine: since there=E2=
=80=99s only one
grub.cfg, we just store the menu entries that are defined in
=E2=80=98operating-system=E2=80=99 at the moment =E2=80=98guix system recon=
figure=E2=80=99 is run.  This
part is =E2=80=9Cimperative=E2=80=9D in nature.

> It would be very convenient if we could just store the entire
> <grub-configuration> in the built system output (e.g., the parameters
> file).  Is that possible?

I don=E2=80=99t think it=E2=80=99s useful because what matters is the
<grub-configuration> that we see in the new operating system.

What do you think?

>> However, the activation script is indeed missing.  We can add it to the
>> output of =E2=80=98guix system build=E2=80=99 by extending =E2=80=98syst=
em-service-type=E2=80=99:

[...]

>> This way we have direct access to each generation=E2=80=99s activation s=
cript
>> and we should be fine with (3).
>>
>> WDYT?
>
> I'm afraid I don't yet know enough about gexps and the activation
> process to give an informed opinion on that suggestion.  After I finish
> the first milestone (switch symlinks and rebuild grub.cfg), I'll study
> those topics in more detail and revisit your proposal.

Sure.

Thank you!

Ludo=E2=80=99.