Re: Guix on Mobile (Was: Interest check: U-Boot bootloader support)

[Jookia]

On Mon, Feb 22, 2016 at 10:01:15AM -0800, Christopher Allan Webber wrote:
> If we would like to also be able to deploy Guix to mobile devices, this
> could really be great.  I'm sure a number of us would like to imagine a
> world in which we can run Guix and more a GNU-ish type environment in
> userspace on our mobile computers (how I miss my Nokia N900!)
> 
> How complex do you think it would be?

On the Neo900 it might be easy to do, but given most phones don't have a
keyboard it'd require another bootloader than U-boot or GRUB. Which is okay,
I've been thinking about this anyway and plan to make one eventually. Basically
the bootloader would just be Linux to do some hardware init (touch screen, etc)
then you'd select which Guix generation to load and it'd get kexec'd. This would
also allow full disk encryption if the bootloader were on a different chip to
root.

I've toyed with the idea of such a bootloader ('GuixBoot') for a bit in my head
and seen some interest for it. It'd solve a lot of issues of my own even on
systems with GRUB and U-Boot as Linux tends to initialize hardware better than
them (neither U-Boot nor Libreboot like either of the EDID values of my screen!)
and would probably allow faster bootup given you're not initializing the
hardware twice.

The biggest problem with this would be size, a typical kernel and initrd is
around 12 megabytes together while a 'good' flash chip is probably 8 megabytes,
though I know some Libreboot machines have 4 megabytes. I also don't know of any
open hardware boards that have flash chips for loading kernels or bootloaders,
so perhaps it isn't an issue if we put this as an unencrypted /boot. I solve
this dilemma on my machine but using a fully encrypted SSD coupled with an
unencrypted /boot on an SD card.

Perhaps booting off a USB key in general would be a better habit to get in to,
which works on all machines and allows full disk encryption and allows me to
somewhat verify my machine hasn't been tampered with.

Anyways, I plan to try the idea sometime once I have a Guix system setup. If I
can get it small enough (I have no knowledge how, don't hold your breath) it'd
be useful as a payload in Libreboot I've heard.

>  - Chris

Jookia.