Re: wip blog post: running Guix System on ARM

[Julien Lepiller]

Le Thu, 14 Nov 2019 12:05:34 +0100,
"pelzflorian (Florian Pelz)" <address@hidden> a écrit :

> On Thu, Nov 14, 2019 at 10:29:22AM +0100, Pierre Neidhardt wrote:
> > Neat, thanks for this article!
> >   
> 
> Yes, thank you!  I have not tried yet though.
> 
> Maybe add the top add instructions what to do if installation fails
> (i.e. flash the SD with another operating system and start anew).
> 
> 
> > > Make sure there is an empty /etc, or the new system won't boot
> > > properly.  
> > 
> > Isn't this a bug in Guix?
> > 
> >   
> 
> Is installing on the same drive an “official” installation method?  I
> mean, it probably works and people can ask for help after using it,
> but remaining files from the old system could be problematic.  If this
> is dangerous (is it?) then please add a warning.

It's not officially recommended, but we have used and proposed it on
IRC in the past.  The overdrive at my place, as well as my own server
both were installed using that method.

> 
> Also, I wonder:
> 
> On Wed, Nov 13, 2019 at 10:21:54PM +0100, Julien Lepiller wrote:
> > Then, initialize the system with:
> > 
> > ```bash
> > mount /dev/sda1 /mnt
> > mkdir /mnt/etc
> > $EDITOR /mnt/etc/config.scm # create the configuration file
> > guix system init /mnt/etc/config.scm /mnt
> > ```  
> 
> So the mmcblk you install on is different from the running system’s
> mmcblk, otherwise how could you keep your old system’s SD card?
> 
> Then the mmcblk device number will change on the running Guix System
> and the config.scm will have to be adapted to use the mmcblk before
> reconfiguring from the installed Guix System.
> 
> Otherwise if you install on the same mmcblk as the running system,
> then maybe this could fail if the u-boot partition is too small?  That
> would leave both the existing operating system and the new Guix System
> unusable.  Maybe there should be more of a warning.
> 
> > ### The bootloader
> > 
> > Because of the way the Guix System is designed, you cannot use an
> > already existing bootloader to boot your system: it wouldn't know
> > where to look for the kernel, because it doesn't know its store
> > path.  It wouldn't be able to let you boot older generations
> > either.  Most boards use the u-boot bootloader, so we will focus on
> > that bootloader here.  
> 
> 
> More generally, since no old Guix generation can be selected in pure
> u-boot when booting (I think) this warrants more of a warning that one
> important feature of Guix is missing.

I must have expressed myself badly, sorry. It's perfectly possible to
select older generations from u-boot.  I was talking about the u-boot
from the foreign distro, but I was wrong on that too ^^'. So you can
always select an older generation.

> 
> For later: What would a rescue of a broken Guix System look like?  I
> do not know if all this works better with grub-efi on supported ARM
> systems; I have never tried.
> 
> For later, maybe in the manual: Maybe it would be interesting how to
> create a reusable SD install image for Guix.  I also remember there
> were discussions about making ci.guix.gnu.org build a two-part
> bootable installation image in the past, one part with a bootloader
> for a specific board and another part general for all boards.
> 
> Regards,
> Florian