bug#44353: [PATCH version-1.2.0 v2] guix: system: Add a new '--non-volatile' option for disk-image.

[Maxim Cournoyer]

Hello Mathieu,

Mathieu Othacehe <othacehe@gnu.org> writes:

> Hello Maxim,
>
>> * guix/scripts/system.scm (%options)[volatile-root?]: New boolean option.
>> (%default-options): Set its default value to #f.
>> (show-help): Add help doc.
>> * guix/scripts/system.scm (perform-action): Propagate option...
>> (system-derivation-for-action): ...here.  Use it to set the volatile-root?
>> field of the image object passed to SYSTEM-IMAGE.
>> * doc/guix.texi (Invoking guix system): Document it.
>
> This is a nice addition and it looks good to me.
>
> Thanks,
>
> Mathieu

One thing I wasn't sure was if it'd be better to implicitly derive
volatile-root? #f when image-type was specified (not (eq? 'guess)).  The
rationale being that users specifying the image-size themselves probably
want to make use of extra space (assumption) but can't unless
volatile-root? is #t on the image.

If we choose the above it'd lead to less code and one less switch; on
the other hand it is not as explicit.

What do you think?

Maxim