Hello,

To build a Guix System image, one needs to pick an operating system file
and call "guix system disk-image my-os.scm" to get an image.

While this works fine on desktop, this is more tricky for the embedded
devices. Which operating system to select in "examples" folder? What's
the difference between --system and --target, which one should I use?

My idea is to provide a catalog of images, that we would maintain (at
least adding them to the CI). The image definition would select a
default operating-system, an image type and a system/target to
build/cross-build the image.

This attached, wip patch, allows to run (on wip-hurd-vm branch):

--8<---------------cut here---------------start------------->8---
guix system image hurd-disk-image
--8<---------------cut here---------------end--------------->8---

instead of:

--8<---------------cut here---------------start------------->8---
guix system disk-image --target=i586-pc-gnu  gnu/system/examples/bare-hurd.tmpl
--8<---------------cut here---------------end--------------->8---

and

--8<---------------cut here---------------start------------->8---
guix system --list-images
--8<---------------cut here---------------end--------------->8---

that for now reports:

--8<---------------cut here---------------start------------->8---
The available images are:

  - hurd-disk-image
--8<---------------cut here---------------end--------------->8---

We could extend it to other boards that we've been hacking on
(beaglebone-black, pinebook-pro ...).

Please tell me what do you think!

Thanks,

Mathieu