bug#36855: guix system switch-generation doesn't

[Mark H Weaver <mhw@netris.org>]

Hi,

Ludovic Courtès <ludo@gnu.org> writes:

> Jakob, now that we generate scripts for the effectful bits of system
> reconfiguration (one of these bits being service upgrades), couldn’t we
> take it one step further and store those scripts in the “system”
> derivation so we can run them eventually, notably upon
> ‘switch-generation’?

As a bonus, this approach might solve another issue I've observed: on my
Guix system, where I build everything locally, several derivations are
built *during* activation.  Based on the terminal output, I get the
impression that the system is compiling things while the system in an
intermediate state, when some of the activation steps have been done,
but not all of them.

As I recall, the derivations built during activation are limited to
compiled modules for Guile, but it still sometimes takes on the order of
a minute or two on my laptop to complete the "activating system" steps.
This seems suboptimal.

The next time I update my system, I'll try to remember to keep a
transcript of this, so that I can be more specific.

      Best,
       Mark