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

[Mathieu Othacehe <othacehe@gnu.org>]

Hello Maxim,

> 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?

When developing the image API, I hesitated keeping the default of using
volatile root file systems by default.

In most cases, I think that the user may prefer to have non volatile
images. They already have to copy the image from the store and make it
writable so that QEMU can use it with "-hda" argument.

Switching the default to non volatile could be an option I think. Doing
what you are proposing: setting volatile to false when image-size is
passed could also be a first step.

Thanks,

Mathieu