nixos-4screen/docs/nixos_build_spec.md

NixOS Build Spec (sam-4screen-desktop)

Disk / Boot (WIPE ENTIRE NVMe DISK)

Target disk: /dev/nvme0n1

• Size: 953.87 GiB (1024209543168 bytes), 2000409264 sectors
• Model: PM951 NVMe SAMSUNG 1024GB
• NVMe serial: S2FZNXAH301424
• NVMe WWID: nvme.144d-2020202020205332465a4e584148333031343234-504d393531204e564d652053414d53554e4720313032344742-00000001
• Sector size (logical/physical): 512 bytes / 512 bytes

DECISION (CONFIRMED):

• Do NOT keep Windows.
• Wipe the entire /dev/nvme0n1 (all existing partitions will be deleted/overwritten).

Installer safety:

• Install target is NVMe only. Do not select /dev/sdX devices in the installer.
• Device names like /dev/sdb, /dev/sdc can change across boots; always rely on UUID/label when mounting non-target disks.

Verification commands (run before wiping, if you want one last check):

• lsblk -o NAME,SIZE,TYPE,FSTYPE,LABEL,UUID,MOUNTPOINTS
• sudo fdisk -l /dev/nvme0n1

Boot method:

• UEFI
• Bootloader: systemd-boot

Filesystem / layout:

• Root filesystem: Btrfs (with subvolumes)
• Encryption: none
• Swap: zram
• Hibernate: no
• /home: Btrfs subvolume

Partitioning approach:

• Manual in the installer (no disko)

Recommended layout:

• New GPT on /dev/nvme0n1
• EFI System Partition (vfat), mounted at /boot
• Btrfs partition for the rest
  • Subvolume @ mounted at /
  • Subvolume @home mounted at /home

IMPORTANT:

• hosts/sam-4screen-desktop/hardware-configuration.nix is currently a placeholder.
• During install after mounting to /mnt:
  1. Run: nixos-generate-config --root /mnt
  2. Copy: /mnt/etc/nixos/hardware-configuration.nix into: hosts/sam-4screen-desktop/hardware-configuration.nix

Other attached disks (DO NOT FORMAT)

• /dev/sda (240GB) model: Patriot Burst El (KEEP)
  • /dev/sda1: Microsoft reserved partition (~15MiB)
  • /dev/sda2: NTFS label "Back Up" (keep)
• TempBackup (ext4) UUID=4f9c4bd5-fea5-408f-9370-731fc095da3f (~465GiB/500GB) (KEEP)
  • Model: WD5000BEVT-22ZAT
  • Serial: WD-WXNY08ND2684
  • NOTE: device name may appear as /dev/sdX depending on boot/USB order; identify by UUID/label/model.
• Integral300 (ext4) UUID=27febd74-20aa-4a3a-92c1-6fdd1ad7e88e (~298GiB/320GB)
  • Mount at /data
  • NOTE: device name may change; config always uses /dev/disk/by-uuid.
• XPSystemDrive (ext4) UUID=82c994f1-9adb-49e4-ba1e-5b6e5ccbd49b (~149GiB/160GB) (KEEP)
  • Model: HTS541616J9SA00 (Hitachi)
  • NOTE: device name may appear as /dev/sdX depending on boot/USB order; identify by UUID/label/model.

Networking

• Use NetworkManager

Static IPv4 policy (CONFIRMED):

• Static IPv4 should be applied to Wi-Fi SSID:
  • SSID / connection id: "Aussie Broadband 8729"
  • Interface: wlp4s2
  • IP: 192.168.20.27/24
  • Gateway: 192.168.20.1
  • DNS: 192.168.20.35, 192.168.20.13
• Wired enp0s31f6: no static IP required for now

Secrets policy:

• Do not commit Wi-Fi PSKs to git.
• Static IP enforcement is implemented via a NetworkManager dispatcher script.

Data drive mount

• Integral300 ext4 UUID=27febd74-20aa-4a3a-92c1-6fdd1ad7e88e
• Mountpoint on NixOS: /data (preferred)

Dotfiles policy

• Dotfiles live on the installed system at: ~/dotfiles
• Do not depend on /data for dotfiles.

Desktop

• Primary compositor: Niri
• Display/login manager: greetd + tuigreet
• Session start command: niri --session (do not use niri-session)
• GPU: Intel HD 630 + NVIDIA Quadro P620
• Display appears to be driven by NVIDIA Quadro P620 (observed /dev/fb0 on Ubuntu scan). Treat NVIDIA as primary unless proven otherwise.

Secrets policy

• No API keys or WiFi PSKs committed to git