Add Steam Deck Support

[Hoverbear]

The Steam Deck has a read-only root, so it demands some special attention. This is also a good way to test plan flexibility.

Testing instructions are in src/planner/linux/steam_deck.rs and copied here:

One time step:

1. Grab the SteamOS: Steam Deck Image from https://store.steampowered.com/steamos/download/?ver=steamdeck&snr=

2. Extract it (this can take a bit)

   bunzip2 steamdeck-recovery-4.img.bz2

3. Create a disk image

   qemu-img create -f qcow2 steamos.qcow2 64G

4. Start a VM to run the install onto the created disk

   Note:

   RECOVERY_IMAGE=steamdeck-recovery-4.img
   nix build "nixpkgs#legacyPackages.x86_64-linux.OVMF.fd" --out-link ovmf
   qemu-system-x86_64 -enable-kvm -smp cores=4 -m 8G \
       -device usb-ehci -device usb-tablet \
       -device intel-hda -device hda-duplex \
       -device VGA,xres=1280,yres=800 \
       -drive if=pflash,format=raw,readonly=on,file=ovmf-fd/FV/OVMF.fd \
       -drive if=virtio,file=$RECOVERY_IMAGE,driver=raw \
       -device nvme,drive=drive0,serial=badbeef \
       -drive if=none,id=drive0,file=steamos.qcow2

5. Pick "Reimage Steam Deck". Important: when it is done do not reboot the steam deck, hit "Cancel"

6. Run sudo steamos-chroot --disk /dev/nvme0n1 --partset A and inside run this

   steamos-readonly disable
   echo -e '[Autologin]\nSession=plasma.desktop' > /etc/sddm.conf.d/zz-steamos-autologin.conf
   passwd deck
   sudo systemctl enable sshd
   steamos-readonly enable
   exit

7. Run sudo steamos-chroot --disk /dev/nvme0n1 --partset B and inside run the same above commands

8. Safely turn off the VM!

Repeated step:

1. Create a snapshot of the base install to work on

   cp steamos.qcow2 steamos-hack.qcow2

2. Run the VM

   nix build "nixpkgs#legacyPackages.x86_64-linux.OVMF.fd" --out-link ovmf
   qemu-system-x86_64 -enable-kvm -smp cores=4 -m 8G \
       -device usb-ehci -device usb-tablet \
       -device intel-hda -device hda-duplex \
       -device VGA,xres=1280,yres=800 \
       -drive if=pflash,format=raw,readonly=on,file=ovmf-fd/FV/OVMF_CODE.fd \
       -drive if=pflash,format=raw,readonly=on,file=ovmf-fd/FV/OVMF_VARS.fd \
       -drive if=virtio,file=steamos-hack.qcow2 \
       -device virtio-net-pci,netdev=net0 \
       -netdev user,id=net0,hostfwd=tcp::2222-:22

3. Do your testing! You can ssh deck@localhost -p 2222 in and use rsync -e 'ssh -p 2222' result/bin/harmonic deck@localhost:harmonic to send a harmonic build.
4. Delete steamos-hack.qcow2

[Hoverbear]

https://lists.freedesktop.org/archives/systemd-devel/2022-October/048426.html

tl;dr: you should add a normal service to /etc/systemd, and use ExtensionImages= to make the service have the ext activated in its mount namespace

[Hoverbear]

It's in a good enough state I'd install it on my own device now, in fact I will tomorrow. :)

[Hoverbear]

... Github Actions isn't building the right checkout? What?

[cole-h]

I tested it and it seemed to work. Rebooted and it still worked, too! Some doc comments went missing, so I added suggestions for them below.

---

One thing that could be improved overall is that we never tell the user they may need to reload their environment (by opening a new terminal or exec $SHELL or something). If you run it without -v, it just silently exits (which is fine, though I would like some indication that it completed successfully by default...), and if you try to nix-shell right after that, it won't work and the user is left guessing if it actually completed, or if something went wrong. I'll make a ticket about this.

[cole-h]

Failed CI because there's no buildkite stuff setup in this branch. I think that's fine.

[Hoverbear]

Thank you for the fixes! :)