# Omarchy 3.5.1 upgrade breaks internal keyboard/trackpad on MacBookAir6,2 (Limine 11.3.1 regression)

## Summary

The Omarchy 3.5.0 → 3.5.1 upgrade pulls in Limine 11.3.1 (from 11.2.0), which breaks the internal USB keyboard and trackpad on MacBookAir6,2. The devices work at the Limine boot menu but become completely unresponsive after Linux boots. Downgrading Limine to 11.2.0 resolves the issue. A corresponding bug has been filed with the Limine project.

## Environment

- **Hardware:** MacBookAir6,2 (Mid-2013, Haswell)
- **Working:** Omarchy 3.5.0 with Limine 11.2.0
- **Broken:** Omarchy 3.5.1 with Limine 11.3.1
- **Kernels tested:** 6.19.10, 6.19.11 — both exhibit the same failure

## Problem

The internal keyboard (`05ac:820a`) and trackpad (`05ac:820b`) connect via USB through an internal Broadcom hub. After the 3.5.1 upgrade, they enumerate normally during boot but their HID input scanning subsystem is dead — the firmware responds to USB control requests but cannot produce any key or touch input data.

The root cause is **Limine 11.3.1**, not the kernel or any Omarchy configuration change. Evidence:

1. Kernel configs are identical across 6.19.9, 6.19.10, and 6.19.11
2. Initramfs module sets are identical between old and new UKIs
3. Btrfs snapshot rollback to the pre-upgrade root filesystem (snapshot 29, Omarchy 3.5.0, kernel 6.19.10) still fails — because `/boot` (ESP) is a separate FAT32 partition not included in snapshots, so the new Limine persists
4. Keyboard works at the Limine boot menu but dies during the EFI→Linux xHCI handoff
5. Restoring Limine 11.2.0 from the pacman package cache fixes the issue completely

## Additional issue: btusb and the Broadcom hub

Separately from the Limine regression, the `btusb` module causes USB disconnects on the same Broadcom hub when it initializes the Bluetooth controller (`05ac:828f`). This has likely always been an issue on MacBookAir6,2 but was masked until the Limine bug made the keyboard unable to recover from the disconnect. MacBook users running Omarchy may benefit from a note about blacklisting `btusb` if they experience intermittent keyboard/trackpad drops:

```bash
sudo bash -c 'cat > /etc/modprobe.d/no-btusb.conf << EOF
blacklist btusb
install btusb /bin/true
EOF'
sudo mkinitcpio -P
```

This disables Bluetooth but prevents the hub disruption.

## Confirmed fix

Downgrading Limine to 11.2.0 fully restores keyboard/trackpad functionality with the latest Omarchy 3.5.1 and kernel 6.19.11:

```bash
sudo pacman -U /var/cache/pacman/pkg/limine-11.2.0-1-x86_64.pkg.tar.zst
```

An SMC reset is required after downgrading to recover the keyboard hardware from the hung state:

1. Power off, unplug charger and all USB devices
2. Hold Left Shift + Control + Option + Power for 10 seconds
3. Plug in charger, power on

Pin Limine to prevent re-breakage: add `IgnorePkg = limine` under `[options]` in `/etc/pacman.conf`.

## Suggestion

Consider one or more of the following:

- **Pin Limine < 11.3.1** until the upstream Limine bug is fixed
- **Add a known-issue note** for MacBook users in the Omarchy release notes or wiki
- **Add `applespi` to a default blacklist** for MacBook hardware — the module is for newer MacBooks with SPI keyboards and is unnecessary on MacBookAir6,2 (USB keyboard). Its SPI probe fails harmlessly but it adds noise to the boot log

## Investigation details

A full diagnostic log with kernel log analysis, USB probing results, and the complete elimination process is available. Key suspects that were ruled out:

| Suspect | Result |
|---------|--------|
| `applespi` module | Not the cause — blacklisted, no change |
| `btusb` module | Causes USB disconnects but not the root HID failure |
| `wl` (broadcom-wl) | Loads too late to affect keyboard |
| Kernel 6.19.11 regression | Same failure on 6.19.10 |
| Kernel config / initramfs | Identical across versions |
| Hardware failure | Ruled out — keyboard works at EFI boot menu and after Limine downgrade |