Problems with upgrade

I got my D8 from Vikings in November 2020, the only issue so far is that sometimes, coreboot does not complete its work and then the system does not start. In that case, I press reset and the next time it usually starts but it happened I had to press reset 2 or 3 times before successful boot.

At first, I misundersood what the reset button was so I could not boot. With a raspberry pi 2b, an USB-serial adapter and a null model cable (the Tx pin on one side of the cable is connected to the Rx pin on the other side of the cable, unlike a straight serial cable), I could see coreboot messages from the D8 and this is how I realized that what I thought was the reset button actually had no effect, then I tried pressing whatever I could and saw what was making coreboot restart, which I initally thought was a cache for an audio plug!

If you can't see coreboot messages, indeed it is a little frustrating. In that case try pressing other buttons (or even things that don't look like buttons) if the screen remains dark for more than 30s.

Besides, I have noticed that the graphic card I have is no more in the current offer, so we may have not exactly the same hardware.

In case that helps to compare with your system, I attach the ouput of 'sudo lshw' and coreboot logs with two resets until successful boot, visible with "soft_reset() called!".

"ISO" -- that would be System Rescue CD.

https://www.system-rescue.org/

I suspect that my problems are similar to Avron's and Korax's, so I tried some of the things mentioned in this thread and the one titled "Change boot device".

Thanks to Magic Banana's advice in the thread titled "Change boot device", I got my system to show me a GRUB screen:
GNU GRUB version 2.02
┌────────────────────────────────────────────────┐
│*Trisquel GNU/Linux                             │
│ Advanced options for Trisquel GNU/Linux        │
│ Memory test (memtest86+)                       │
│ Memory test (memtest86+, serial console 115200)│
│                                                │
└────────────────────────────────────────────────┘
When I choose "Memory test (memtest86+)", I get a nice blue-background screen titled "Memtest86+ 5.01" with options and information (see attached file if you read this on the forum instead of the mailing list), but after a few seconds, that screen is replaced with rainbow-coloured flashing mojibake on a black background (see attached file) and stays that way.

Among the blue screen's options are "Press F1 to enter Fail-Safe Mode", "Press F2 to force Multi-Threading (SMP)" and "(c)configuration".
So, on my next try, instead of doing nothing, I hit the "c" and "F1" keys while the blue menu was showing, but still got the rainbow mojibake flashing on a black background.

So I still don't know how to memtest, nor whether I should want to.

Oh, and $ sudo update-grub which Magic Banana advised in the "Change boot device" thread gave me this:
Sourcing file `/etc/default/grub'
Generating grub configuration file ...
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
Found linux image: /boot/vmlinuz-5.10.20-gnu
Found initrd image: /boot/initrd.img-5.10.20-gnu
Found linux image: /boot/vmlinuz-4.15.0-112-generic
Found initrd image: /boot/initrd.img-4.15.0-112-generic
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
error: cannot seek `/dev/mapper/sda5_crypt': Invalid argument.
Found memtest86+ image: /memtest86+.elf
Found memtest86+ image: /memtest86+.bin
done

By the way, my system freezed again (including the panel clock's seconds counter, but usually excluding the cursor, which I can move fluently while unable to click or type anything) while I prepared to post this. I had to restart and rewrite my post (I had saved it as a TXT file before the freeze, but apparently it didn't survive the hard switch-off, the file was blank after rebooting) to post it here. I suspect Korax encounters similar freezes.

After every boot, a little while after logging in, I have a screen freeze that lasts about 1 or 2 minutes but I have not noticed that it happens again. I suppose this is purely a software issue, screen freeze can be due to a process taking all the CPU for some time. Since it is a rather minor inconvenience, I did not further investigate (the way would be to write down the time and check system logs around that time).

It is only twice that I really decided to reboot, every time it is while using Libreoffice for quite some time, I had no time to wait so I rebooted. Other than that, no problem.

Select boot device:

3. Payload [coreinfo]

I have the same if I press ESC early enough (indeed, when the message shows up it may be too late). I guess if you have more disks, there should be additional entries there. I just added disks, I'll check at next reboot whether it is the case. I tried the other two options already, this nvramcui and coreinfo, it provides a set of messages among which error messages but don't really understand what they mean. At next reboot I will have a look at them and take pictures and I will turn on my log collection on the serial line in case there is something there.

Besides, I had an explanation from Vikings that this is a one-time selection only. Doing a permanent change of booting disk requires reflashing coreboot. I am not sure how easy and safe it is to do that.

I want to say that, while I would appreciate a bit more flexibility on the configuration allowed by coreboot, I don't really have any unsolved issue.