Guix System for embedded systems roadmap.

Guix System for embedded systems roadmap.

[Mathieu Othacehe]

Hello,

At Fosdem 2020, I gave a talk about using GNU Guix as an alternative to
Yocto, focusing on cross-compiling a Guix System. Here's a status and
my personal roadmap on this topic.

* On core-updates, since commit
  d594963856690f1aacf228c8a83e406d33bc44ce, cross-compiling a bare-bones
  Guix System disk-image for Pine A64 works. This is propably true for
  other boards too.

* On the same commit, the produced disk-image weights 1.9 GiB, which is
  obviously too big. I'm working on reducing this closure size. See:
  https://issues.guix.info/issue/39941 and
  https://issues.guix.info/issue/40071.

* While cross-compilation is important, Guix also supports emulated
  compilation with --system. Producing a Guix System disk-image with
  --system is currently broken and needs to be fix. See
  https://lists.gnu.org/archive/html/guix-devel/2019-12/msg00099.html.

* Somehow related to the previous point, producing a disk-image,
  currently means spawning a virtual machine. This can be very slow, and
  using --system, we currently emulate the execution of a virtual
  machine for a foreign architecture.

  I'd like to propose an alternative mechanism which would be faster and
  not involving virtual machines. Maybe producing the disk-image in a
  container?

* Increase board support catalog, even if it's tricky because many
  boards need proprietary blobs to boot (such as Raspberry Pis). The
  effort started by Danny on wip-buildroot could be resumed.

* Finally, as we discussed during Guix Days[1], it would be nice to have
  a webservice, where you could select your board, the packages/services
  you want to install, and a disk-image, cross-compiled or not, would be
  generated for you! It implies that all the points listed above are
  solved, but it could be quite nice :)

Feedback welcome!

Thanks,

Mathieu

[1]:
http://git.savannah.gnu.org/cgit/guix/maintenance.git/tree/doc/guix-days-2020/growing-guix.org

Re: Guix System for embedded systems roadmap.

[Ludovic Courtès]

Hello Mathieu,

Mathieu Othacehe <m.othacehe@gmail.com> skribis:

> At Fosdem 2020, I gave a talk about using GNU Guix as an alternative to
> Yocto, focusing on cross-compiling a Guix System. Here's a status and
> my personal roadmap on this topic.

I’m not much of an embedded person, but this looks like a great
application and it’s great to see progress being made!

> * Somehow related to the previous point, producing a disk-image,
>   currently means spawning a virtual machine. This can be very slow, and
>   using --system, we currently emulate the execution of a virtual
>   machine for a foreign architecture.
>
>   I'd like to propose an alternative mechanism which would be faster and
>   not involving virtual machines. Maybe producing the disk-image in a
>   container?

Unfortunately, I don’t think that’s possible.  The reason we resort to
VMs is that the Linux kernel doesn’t allow you, for instance, to mount a
file system without being root.  So doing things like running Parted,
mounting a file system, and populating it typically requires root
privileges.  (In some cases, there are tools like mksquashfs that can do
that from user-space, but it’s very ad-hoc.)

Thoughts?

> * Increase board support catalog, even if it's tricky because many
>   boards need proprietary blobs to boot (such as Raspberry Pis). The
>   effort started by Danny on wip-buildroot could be resumed.

Speaking of which, I’d love to get my A20 OLinuXino running Guix
System.  :-)

I checked what Buildroot had about that board, but I found the
information to be rather scattered and of varying levels of abstraction,
which made it hard to see if there was anything different from what we
do.

Thanks,
Ludo’.

Re: Guix System for embedded systems roadmap.

[Danny Milosavljevic]

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Hi Ludo,

On Tue, 17 Mar 2020 10:44:25 +0100
Ludovic Courtès <ludo@gnu.org> wrote:

> Speaking of which, I’d love to get my A20 OLinuXino running Guix
> System.  :-)

What is the latest state of it?

I used

  guix system disk-image -s armhf-linux -e '(@ (gnu system install) a20-olinuxino-micro-installation-os)'

after editing the embedded-installation-os to hardcode /dev/vda .

And it just keeps building basic stuff, like util-linux-with-udev etc.

I think I have managed to build an actual disk image for olinuxino only once
in two years (using guix).  Just saying...

Right now, guix will keep building stuff until linux-libre, which will hang at
compilation of some net builtins.

If you want, I can check the image you already have using a serial cable on my
olinuxino micro.

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Re: Guix System for embedded systems roadmap.

[Ludovic Courtès]

Hi!

Danny Milosavljevic <dannym@scratchpost.org> skribis:

> On Tue, 17 Mar 2020 10:44:25 +0100
> Ludovic Courtès <ludo@gnu.org> wrote:
>
>> Speaking of which, I’d love to get my A20 OLinuXino running Guix
>> System.  :-)
>
> What is the latest state of it?

On my side the latest state is: I gave up and installed Debian + Guix.
:-)

> I used
>
>   guix system disk-image -s armhf-linux -e '(@ (gnu system install) a20-olinuxino-micro-installation-os)'
>
> after editing the embedded-installation-os to hardcode /dev/vda .
>
> And it just keeps building basic stuff, like util-linux-with-udev etc.
>
> I think I have managed to build an actual disk image for olinuxino only once
> in two years (using guix).  Just saying...

I did manage to build an image some time ago, no problem there.  I used:

  (list (channel
          (name 'guix)
          (url "https://git.savannah.gnu.org/git/guix.git")
          (commit
            "d08c3e51ab62575e722aec24fba42a0cb84198cc")))

The thing wouldn’t boot, though.

Ludo’.