Add T490 hardware configuration and docs
- modules/t490.nix: TLP power management, CPU throttling (throttled), S3 sleep, remote Nix builders (cluster), fwupd, fprintd, fprintd, Syncthing, Tailscale, Intel VA-API, TrackPoint sensitivity, PipeWire defaults - flake.nix: add nixos-hardware input, import T490 module + nixos-hardware - docs/T490-HARDWARE.md: WiFi variants, graphics, audio, fingerprint, sleep guide - docs/T490-BATTERY.md: TLP config, threshold strategy, real-world battery numbers - docs/T490-OFFLOADING.md: local vs cluster split, remote builder setup - MIGRATION.md: add T490 post-install steps (fwupd, fprint, remote build key) - README.md: reflect new module and docs structure
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Scott Scoble
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docs/T490-BATTERY.md
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docs/T490-BATTERY.md
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# T490 Battery Life
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## Hardware Baseline
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- **50 Wh** internal battery (3-cell)
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- Panel draws ~4-5W at typical brightness
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- CPU TDP-up 25W, TDP-down 10W
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## Real-World Estimates
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| Scenario | Runtime |
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|---|---|
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| Idle, screen off | 10-12 hours |
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| Light work (terminal, notes) | 7-8 hours |
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| Dev work (editor, browser, kubectl) | 5-6 hours |
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| Browsing (10+ tabs, video) | 4-5 hours |
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| Compiling / heavy CPU | 1.5-2 hours |
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## TLP Configuration
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`modules/t490.nix` configures:
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- `powersave` governor on battery, `performance` on AC
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- Turbo disabled on battery
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- CPU capped at 40% max frequency on battery (~1.7 GHz)
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- WiFi power saving on battery
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- PCIe runtime PM (auto on battery)
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- Intel GPU frequency limits (300-600 MHz on battery)
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### Battery Health Thresholds
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Lenovo Battery Team recommendations — configured in `modules/t490.nix`:
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- **Start charging** below 40%
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- **Stop charging** at 80%
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- Thresholds persist in firmware (survive reboots without TLP)
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This dramatically extends battery lifespan. Don't leave plugged in at 100% for days.
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## CPU Throttling Fix
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Intel Whiskey Lake CPUs have a bug where BD PROCHOT fires spuriously, locking the CPU at 400 MHz. The nixos-hardware T490 module enables `services.throttled` (erpalma/throttled) — this is mandatory.
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**Skip thermald** — it conflicts with throttled. `services.thermald.enable = false` is set in `modules/t490.nix`.
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## Additional Tweaks
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- `pcie_aspm=force` — force PCIe power saving
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- `i915.enable_rc6=7` — max GPU power saving
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- `noatime,nodiratime` — reduce disk writes
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- **zram swap** at 50% of RAM — faster, saves NVMe writes
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## Quick Wins (No Config Needed)
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- Lower screen brightness (40-60% is plenty — biggest power draw)
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- Disable Bluetooth when not in use
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- Use S3 deep sleep (not s2idle)
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- Close unused browser tabs
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docs/T490-HARDWARE.md
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docs/T490-HARDWARE.md
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# T490 Hardware Compatibility
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## WiFi
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Two possible cards depending on SKU:
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- **Intel Wireless-AC 9560** (CNVio, older) — firmware: `iwlwifi-9000-pu-b0-jf-b0-*.ucode`
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- **Intel Wi-Fi 6 AX200** (M.2, discrete, newer) — firmware: `iwlwifi-cc-a0-*.ucode`
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Both use `iwlwifi` and work out of the box. If AX200 scan fails after suspend, firmware version may be the culprit. The `modules/t490.nix` includes a resume hook that reloads the module.
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## Graphics — Intel UHD 620 (Whiskey Lake)
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Single iGPU. No NVIDIA. No Optimus. Ideal for Linux.
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| Feature | Support |
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|---|---|
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| OpenGL 4.6 | Mesa Iris driver |
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| Vulkan 1.3 | Mesa ANV driver |
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| VA-API decode | H.264, H.265 8-bit, VP9 8+10-bit, MPEG-2, VC-1, VP8 |
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| VA-API encode | H.264 only (no H.265) |
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| DisplayPort over USB-C | Up to 4096×2304 @ 60Hz |
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| HDMI 1.4b | Up to 4096×2304 @ 24Hz |
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## Thunderbolt 3
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One full-speed TB3 port (also USB-C PD). `services.hardware.bolt.enable = true` in `modules/t490.nix`. Lenovo TB3 Dock Gen 2 works — update dock firmware via fwupd.
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## Fingerprint Reader — Synaptics 06cb:00bd
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Works after firmware update. Steps:
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1. `fwupdmgr refresh && fwupdmgr update` — flashes Prometheus firmware
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2. `fprintd-enroll` — enroll fingerprints
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3. Works for sudo, login, and screen unlock via PAM
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Check: `lsusb | grep 06cb` should show `06cb:00bd`.
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## Audio
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Single Intel audio card (`8086:9dc8`) with 5 sub-devices (speaker + 4 HDMI/USB-C). The nixos-hardware T490 module provides a custom PulseAudio profile set that exposes all 5 sinks simultaneously.
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## Sleep / Resume — Critical
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The T490 supports S3 (deep sleep) and S0ix (s2idle, modern standby). Lenovo removed S3 from some BIOS versions.
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**Check:**
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```
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cat /sys/power/mem_sleep
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```
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| Output | Status | Action |
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|---|---|---|
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| `s2idle [deep]` | S3 default | Good |
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| `[s2idle] deep` | S3 exists but not default | Already fixed in `modules/t490.nix` (`mem_sleep_default=deep`) |
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| `[s2idle]` | S3 missing | Troubleshoot below |
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**If S3 is missing:**
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1. BIOS → Config → Power → Sleep State → "Linux" (re-enables S3 on some versions)
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2. Downgrade BIOS (pre-2020 versions have S3)
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3. Use hibernation instead (more reliable than s2idle)
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**Sleep battery drain:**
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- S3 (deep): ~0.5%/hour (~8 days on a 50 Wh battery)
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- s2idle: ~2-4%/hour (1-2 days)
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docs/T490-OFFLOADING.md
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docs/T490-OFFLOADING.md
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# T490 Offloading Strategy
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The k3s cluster (n97, n97-mini) handles CPU-bound work so the T490 stays cool and battery lasts longer.
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## Local (T490)
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Interactive, latency-sensitive, or IO-bound:
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- Firefox (web apps, research)
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- Terminal + shell (`ghostty` + `zellij`)
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- Editor (`nvim`)
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- `kubectl` / `k9s` (just API calls)
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- `git` on small repos
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- `nixos-rebuild switch` (builds go remote, CLI runs locally)
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- SSH client
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- Chat (Signal, Discord)
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- Obsidian
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- Image/document viewing
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## Cluster
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CPU-bound, batch, or service workloads:
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- Heavy Nix derivations during `nixos-rebuild` → remote builders
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- Go/Rust/C compilation → ssh/rsync build remotely
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- Docker/OCI image builds → build where they run
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- Package builds (CI) → Forgejo runners on cluster
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- Data processing, ETL
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- Kubeclaw agent operations
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- Long-running services (Forgejo, registry, web services)
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## Remote Nix Builders
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Configured in `modules/t490.nix`:
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```nix
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nix.distributedBuilds = true;
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nix.buildMachines = [
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{ hostName = "n97-mini"; system = "x86_64-linux"; maxJobs = 4; ... }
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{ hostName = "n97"; system = "x86_64-linux"; maxJobs = 4; ... }
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];
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```
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**Setup:** `ssh-keygen -t ed25519 -f /root/.ssh/remote-build` on T490, copy pubkey to each builder.
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**When it works:** `nixos-rebuild switch --flake .#laptop` ships heavy derivations to the cluster. The T490 only builds what must be local (bootloader, activation scripts).
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## Dev Compilation Patterns
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- **sshfs mount:** Edit locally, files live on cluster → build via SSH
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- **rsync + remote build:** Push source, build, pull binary back
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- **nix develop with builders:** `nix develop .#project --builders "ssh://n97-mini"`
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