Re: Guix on the MNT Reform

[Christine Lemmer-Webber <cwebber@dustycloud.org>]

Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org> writes:

> [[PGP Signed Part:Undecided]]
> On Sat, 04 Sep 2021 21:31:08 -0400
> Christine Lemmer-Webber <cwebber@dustycloud.org> wrote:
>
>> So we probably want to make a u-boot-mnt-reform in
>> gnu/packages/bootloaders.scm
> The issue is that the I.MX8 requires a nonfree firmware for the DDR4
> controller.

Oh really?  And it's not on hardware, needs to be compiled into either
u-boot or the kernel I guess?

I had thought looking at the manual of the MNT Reform that only the HDMI
port required a blob.  This will be disappoiting if we can't get the
Reform into Guix proper soon.  There are of course channels, and maybe
the work here might have to move to one of those locations rather than
getting committed to the main guix repo, but I hope not.

Hm, seems confirmed from the #mnt-reform channel on libera:

<cwebber> hm is this true?
<cwebber> https://lists.gnu.org/archive/html/help-guix/2021-09/msg00035.html
<cwebber> do you need a piece of nonfree firmware to get the reform to boot?
<bluerise> The bootloader contains a training firmware that is supplied to the
           DDR4 controller
<cwebber> I see
<bluerise> So yes, there's a blob that is given to the DDR4 controller
<cwebber> so yes, until that is replaced
<bluerise> 'replaced'?
<cwebber> looks like we won't be able to get the reform in guix proper then
<cwebber> since it has a pretty strict libre policy
<cwebber> but, it could go in a channel I guess

> If you grep for firmware-imx in the u-boot source code you will find
> mentions of it in the READMEs documentation for many I.MX8 boards.

That's too bad.

> So that firmware probably need to be reimplemented as free software
> somehow.

Or:

<bluerise> the trick is to flash the non-free bootloader into the SoM's eMMC
<bluerise> then you don't have to see the non-free software ;)

Of course, though I think a purely libre policy is quite good, the
criticism remains correct that it's a bit absurd that we tend to relax
once we move it "out of sight, out of mind".  But one can only make so
much progress at once.  Maybe some day we'll have hardware that's truly
free from top to bottom.  I do think the Reform helps advance towards
that goal: at least it makes things very incrementally improvable in
ways that other laptop designs do not.  So I would like to get Guix
working with it... even if we have to outsource our process to a
separate channel until a fully free solution exists.

> Alternatively there are some new system on module (SOM) boards that are
> also compatible with the MNT Reform[1] that might at least boot with
> free software.
>
> I've also started documenting the MNT reform on a Liberplanet wiki
> page[2] but it's really a draft at this point.

Maybe of note for that page:

<bluerise> 'If it's connected through PCI, it could be a security issue as
           IOMMUs tend to be too easy to bypass in practice as they are often
           not well configured by various software components like u-boot,
           Linux and so on.'
<bluerise> The i.MX8M has *no* IOMMU

> References:
> -----------
> [1]https://community.mnt.re/t/ideas-for-processors-for-mnt-reform/237
> [2]https://libreplanet.org/wiki/Group:Hardware/research/laptop/Mnt_Reform
>
> Denis.

Thank you for your hard work on this and many other important things to
improve our computing freedom situations, Denis!

> [[End of PGP Signed Part]]