debianito-post-install/docs/firmware.md

# Option 5: Firmware, Wireless & Bluetooth

## 1. What the Debian Package Misses

In standard Debian packaging, the meta-package `firmware-linux-nonfree` collects hardware blobs from many sources. Its dependency rules and conservative versioning mean it often misses vendor-specific firmware for newer or niche network controllers (Realtek Wi-Fi/Bluetooth and Intel Ethernet/Wi-Fi variants in particular).

This script fills that gap. It scans the hardware itself instead of trusting the meta-package's `Recommends` field: detection is separate from installation, so a specific blob (e.g., `firmware-iwlwifi`, `firmware-realtek`) is pulled in only when its hardware ID is present, even if the base package is already installed. The result is no network interface that appears but cannot initialize because its firmware is missing.

## 2. Dual Scan Engine (PCI & USB)

The script scans both the PCI and USB buses with strict filters, which catches more hardware while keeping false positives low:

* **PCI Bus Scanning (`lspci`):** The engine parses `lspci -nn` output specifically targeting lines containing "network controller" or "ethernet controller". This captures both wireless adapters (e.g., Intel AX200) and wired NICs (e.g., Realtek RTL8125 2.5GbE), so Ethernet firmware needs are covered too.
* **USB Bus Scanning (`lsusb`):** The USB scan applies keyword filtering to ignore peripherals unrelated to networking, such as audio devices or card readers. It specifically looks for terms like "wireless", "wifi", "802.11", and "wlan". Bluetooth devices are also detected separately through `PCI_BT_DEVS` and `USB_BT_DEVS`.
* **Deduplication:** The collected device lists are merged into a single array (`dev_list`) so the same hardware is not processed twice across bus categories and the plan stays clean.

## 3. Dynamic Hardware Mapping Matrix

The script employs an associative mapping strategy in `_detect_firmware_needs` to translate raw vendor strings from `lspci`/`lsusb` into specific Debian package names. This mapping handles the "Intel Split" and other vendor-specific requirements:

* **Vendor Filtering:** The engine first filters out generic or unsupported vendors (e.g., non-Realtek, non-Intel, non-Atheros) to avoid unnecessary package pulls.
* **Package Assignment Logic:**
  * **Intel Wi-Fi Hardware** ➔ `firmware-iwlwifi` (Specific driver for wireless chips).
  * **Intel Ethernet Hardware** ➔ `firmware-intel-misc` (Often pulled via `Recommends` of the base package, but explicitly tracked here).
  * **Realtek Hardware** ➔ `firmware-realtek`.
  * **MediaTek / Ralink Hardware** ➔ `firmware-mediatek`.
  * **Atheros / Qualcomm Hardware** ➔ `firmware-atheros`.

So a system with an Intel Wi-Fi 6 card gets `firmware-iwlwifi` queued explicitly, whether or not the base meta-package claims to cover it. The output is rendered as a deduplicated plan with visual indicators (e.g., `[+] package ← hardware`) for user clarity.

## 4. Installation Execution Flow (Atomic Pipeline)

The installation runs through the atomic pipeline in `install_firmware`:

1. **Repository Validation:** The script first verifies that `/etc/apt/sources.list` or `.d/` contains the `non-free` component. If absent, it halts to prevent installation failures.
2. **Plan Rendering & Confirmation:** A diagnostic tree is generated showing detected controllers and planned packages. The user must explicitly confirm ("Apply the network & firmware plan?") before proceeding.
3. **Base Meta-Package Selection (Backports vs. Stable):**
    * If `firmware-linux-nonfree` is already installed, the script checks for a newer version in backports (`${DEBIAN_CODENAME}-backports`). It prompts to upgrade if available, as backports often contain firmware for very recent hardware not yet in stable.
    * If not installed, it presents a choice between Stable (thoroughly tested) and Backports (Recommended for modern hardware).
4. **Sequential Injection:** After the base package is secured, the script iterates through `_DETECTED_FW_PKGS`. It uses `apt-cache policy` to validate availability before installing specific vendor packages (`firmware-realtek`, etc.), skipping those already present or unavailable in repositories.

## 5. Broadcom Wireless Support (DKMS Single-Path)

Broadcom chipsets require proprietary handling because no open-source driver covers most `14e4:*` devices on modern kernels. The current implementation in `firmware.sh:_handle_wireless` uses a **single-path DKMS flow** (`broadcom-sta-dkms` + `wl` module) instead of a 3-tier fallback:

1. **Device detection**: Iterates `PCI_NET_DEVS` (parsed from `lspci -nn` by the on-demand detection battery) and extracts the Broadcom ID `14e4:XXXX`. Non-Broadcom devices are skipped.
2. **Dependency guard**: Verifies `linux-headers-amd64` and `dkms` are available via `apt-cache show`. If missing, shows: `"linux-headers-amd64 or dkms are not available in your repositories."`
3. **User confirmation**: `whiptail --yesno "Install broadcom-sta-dkms, dkms, and wireless-tools?"`
4. **Step-by-step install** (allows partial failure without aborting the whole module):

   ```bash
   _run_cmd "Broadcom Dependencies" "sudo DEBIAN_FRONTEND=noninteractive apt install -y dkms wireless-tools linux-headers-amd64" || true
   _run_cmd "Broadcom Driver" "sudo DEBIAN_FRONTEND=noninteractive apt install -y broadcom-sta-dkms" || true
   ```

5. **Blacklist persistence**: Writes `/etc/modprobe.d/blacklist-broadcom.conf`:

   ```
   blacklist b43
   blacklist b43legacy
   blacklist brcmsmac
   blacklist bcma
   blacklist ssb
   ```

6. **SSH Warning + Module Switch**: Before unloading current WiFi modules, the script warns about SSH disconnection. Then removes conflicting modules and loads the Broadcom driver:

   ```bash
   _msg "Network Warning" "The script is about to unload current WiFi kernel modules to load the Broadcom driver.

If you are connected via SSH over WiFi, YOUR CONNECTION WILL DROP. Please reconnect after a few seconds."
   _run_cmd "Modprobe" "sudo modprobe -r b43 b43legacy b44 bcma brcmsmac brcmfmac ssb wl 2>/dev/null || true" || true
   _run_cmd "Modprobe" "sudo modprobe wl" || true

   ```

7. **Initramfs**: Rebuilds the initramfs to include the new `wl` module:

   ```bash
   _run_cmd "Initramfs" "sudo update-initramfs -u" || true
   ```

1. **Combo BT handling**: If a Broadcom Bluetooth device is also present (`PCI_BT_DEVS` grep `broadcom`), writes `softdep wl post: btusb` to `/etc/modprobe.d/broadcom-combo.conf`

2. **Post-DKMS verification**: Checks for `/lib/modules/$(uname -r)/updates/dkms/wl.ko*`. If missing, shows the last 20 lines of `dmesg` and offers `dpkg-reconfigure broadcom-sta-dkms`. On success, verifies `lsmod | grep ^wl` and reports `Broadcom WiFi activated (wl module loaded)` or `driver installed but wl module did not load — reboot required`.

USB Broadcom (`0a5c` vendor, `lsusb`) is detected but **not auto-installed**: the script shows a message that Linux lacks native drivers for most USB Broadcom WiFi chips and that `ndiswrapper` may be needed.

> **Historical note:** Earlier drafts of this document described a 3-tier system (`firmware-brcm80211` → `firmware-b43-installer` → `broadcom-sta-dkms`). The current script has consolidated to the DKMS path only. The other firmware packages are still available via the base `firmware-linux-nonfree` metapackage and vendor-specific packages (`firmware-realtek`, etc.).

## 6. Bluetooth Stack Integration

Bluetooth support is handled through a dedicated module (`bluetooth.sh`) that reuses the firmware module's device detection:

* **Hardware Detection:** The script identifies both PCI and USB Bluetooth controllers via the `PCI_BT_DEVS` and `USB_BT_DEVS` arrays, covering all Bluetooth hardware types.
* **Base Stack Installation:** When Bluetooth hardware is detected, the system installs the core stack (`bluez`, `bluez-utils`, `bluez-obexd`) if not already present.
* **Desktop Environment Optimization:** Based on the detected desktop environment:
  * **KDE:** Installs `bluedevil` and optionally `pipewire-pulse` + `wireplumber` for Pipewire audio server integration.
  * **GNOME:** Uses built-in GNOME Bluetooth support in `gnome-control-center`.
  * **XFCE/Other:** Installs `blueman` as the GTK Bluetooth manager.
* **Service Management:** The script enables and starts the Bluetooth service on boot, and recommends a session restart or reboot so desktop applets load properly.

Bluetooth handling stays separate from network firmware; both share the same device detection arrays.