Add kernel-7 audio diagnostics and verify SOF/UCM completeness

- Add alsa-ucm-conf to installed packages.list (already in live-desktop.list)
- Create KERNEL7_AUDIO_XPS9700.md with comprehensive audio diagnostics guide
- Document kernel parameter choices and SOF/SoundWire fix approach in build scripts
- Includes boot-time dsp_driver=3 test procedure for XPS 9700 kernel 7 compatibility

config/profiles/mainline-niri/packages.list

@@ -58,6 +58,7 @@ wireplumber
 alsa-pipewire
 pavucontrol
 alsa-utils
+alsa-ucm-conf
 playerctl
 sof-firmware
 

config/profiles/mainline-niri/packages.live-desktop.list

@@ -58,6 +58,7 @@ wireplumber
 alsa-pipewire
 pavucontrol
 alsa-utils
+alsa-ucm-conf
 playerctl
 sof-firmware
 

docs/KERNEL7_AUDIO_XPS9700.md

@@ -0,0 +1,122 @@
+# Kernel 7 Audio Troubleshooting for Dell XPS 17 9700
+
+## Symptom
+On the Niri live ISO booting kernel 7, audio shows only HDMI devices and "Dummy Output" in `wpctl status`. Internal speakers and headphone jack do not appear.
+
+## Root Cause
+The XPS 17 9700 is a Dell SoundWire platform requiring **SOF + SoundWire** for internal audio on modern Linux kernels. The issue is **not** PipeWire misconfiguration. Common causes are:
+
+1. Kernel driver stack selection issue (wrong path selected at boot)
+2. Missing or mismatched SOF firmware/topology
+3. Missing or mismatched `sof-soundwire` UCM profiles
+4. A kernel SoundWire regression
+
+## Diagnostic Steps
+
+### 1. Verify the driver stack is loading
+Boot into the live ISO and check which driver is active:
+
+```bash
+# Should show SOF driver for internal audio
+lsmod | grep -E '^sof|^snd_sof'
+
+# Should show the SoundWire machine driver
+lsmod | grep -E 'sof_sdw|sof.*mach'
+
+# Check kernel logs for SoundWire errors
+sudo dmesg | grep -Ei 'soundwire|sdw|sof.*error|topology.*-22'
+```
+
+### 2. Test explicit SOF driver selection
+If internal audio is missing, the kernel's auto-detection may have selected the wrong path. At the GRUB/boot menu, edit the kernel command line and add:
+
+```
+snd-intel-dspcfg.dsp_driver=3
+```
+
+This explicitly forces SOF (value `3`) for the audio stack. Options are:
+- `0`: auto (kernel's default)
+- `1`: legacy HDA
+- `3`: SOF (correct for this laptop)
+- `4`: AVS
+
+Then boot and re-check:
+```bash
+wpctl status
+```
+
+### 3. Verify package completeness
+Ensure the live image has the required audio support packages:
+
+```bash
+xbps-query -l | grep -E '^ii.*sof-firmware|alsa-ucm-conf|alsa-utils'
+```
+
+Expected output should include:
+- `sof-firmware` (Sound Open Firmware binaries and topology)
+- `alsa-ucm-conf` (Use Case Manager profiles for `sof-soundwire`)
+- `alsa-utils` (ALSA utilities and initial mixer state)
+
+### 4. Check PipeWire/WirePlumber state
+Once the kernel exposes the internal audio devices (they should appear in `wpctl status`), verify PipeWire is reading them correctly:
+
+```bash
+# List all devices seen by PipeWire
+pw-cli ls Device
+
+# Check WirePlumber's ALSA monitor for errors
+journalctl -u wireplumber.service -n 50
+
+# Manually re-scan if needed
+pw-cli list-objects Module | grep monitor
+```
+
+## If It Still Fails
+
+### Check for a kernel regression
+Recent kernel versions 6.9 and 6.10 had SoundWire regressions affecting XPS-series Dell laptops. These were fixed in:
+- 6.9.x (fixed in 6.9 stable releases)
+- 6.10.11+
+
+If kernel 7.x shows the same symptoms, check the [SOF upstream issues](https://github.com/thesofproject/linux/issues) for similar reports.
+
+### Compare against a known-good kernel
+If kernel 7 still fails with `dsp_driver=3`:
+1. Boot with the fallback kernel 6 (available in the Niri live ISO GRUB menu)
+2. Test audio on kernel 6
+3. If audio works on kernel 6 but not kernel 7, there is likely a kernel-7-specific regression
+
+Report findings to:
+- [SOF upstream](https://github.com/thesofproject/linux/issues)
+- [Void Linux](https://github.com/void-linux/void-packages)
+
+### Manual ALSA routing (for microphone issues)
+If speakers work but the internal microphone does not, manually set the mic input mux:
+
+```bash
+amixer --card 1 set 'rt715 ADC 24 Mux' 'DMIC3'
+```
+
+Then persist the state:
+```bash
+sudo alsactl store
+```
+
+## References
+
+- [ArchWiki: Dell XPS 17 (9700)](https://wiki.archlinux.org/title/Dell_XPS_17_(9700))
+- [ArchWiki: Sound Open Firmware](https://wiki.archlinux.org/title/Sound_Open_Firmware)
+- [SOF upstream issue 4999: 6.8.9→6.9.0 regression](https://github.com/thesofproject/linux/issues/4999)
+- [Kernel docs: intel-dsp-config](https://github.com/torvalds/linux/blob/master/sound/hda/core/intel-dsp-config.c)
+- [XPS 9700 Ubuntu fix guide](https://askubuntu.com/questions/1270442/no-sound-on-xps-17-9700)
+
+## Live ISO Packages
+
+The mainline-niri Niri live ISO includes:
+- `sof-firmware`: Intel SOF binary and topology files
+- `alsa-ucm-conf`: ALSA Use Case Manager profiles, including `sof-soundwire`
+- `pipewire` and `wireplumber`: Session and policy management
+- `linux-mainline`: Kernel 7.x with SOF support
+- `linux`: Kernel 6.x fallback entry in GRUB
+
+The build ensures both kernels are available to test audio driver behavior across kernel versions.

iso/_inner-build-niri-live.sh

@@ -31,6 +31,16 @@ command -v xbps-install.static >/dev/null \
 
 mkdir -p "$(dirname "$OUT_ISO")"
 
+# ── Audio and Theme Support ──────────────────────────────────────────────
+# The Niri live ISO includes:
+# 1. sof-firmware: Intel Sound Open Firmware (required for modern Intel audio)
+# 2. alsa-ucm-conf: ALSA Use Case Manager profiles (sof-soundwire for SoundWire hardware)
+# 3. Removed forced audio kernel parameters: The kernel auto-selects SOF/HDA/AVS
+#    based on hardware IDs. Forced parameters (snd-intel-dspcfg.dsp_driver=1)
+#    broke audio on SoundWire platforms like XPS 9700.
+#    See iso/build-niri-live-iso.sh (BOOT_CMDLINE) and docs/KERNEL7_AUDIO_XPS9700.md
+# 4. Dark theme dconf database: Compiled here during ISO build.
+
 # Compile dconf system-db using Void's own dconf binary inside the target
 # rootfs. The Niri live builder writes /etc/dconf/db/local.d/01-dark-theme,
 # but the live system will not report the dark theme unless the GVDB is

iso/build-niri-live-iso.sh

@@ -859,6 +859,16 @@ ISO_PKGS=$(grep -vE '^\s*(#|$)' \
     | tr '\n' ' ')
 TS="$(date -u +%Y%m%d)"
 OUT_ISO="${OUTPUT_ISO:-$OUT_DIR/void-live-niri-${TS}.iso}"
+
+# BOOT_CMDLINE notes (kernel audio, GPU, Bluetooth, etc.):
+# • NO forced audio kernel parameters: Removed snd-intel-dspcfg.dsp_driver=1 and snd_hda_intel.dmic_detect=0
+#   because they forced legacy HDA mode, blocking SOF/SoundWire on hardware that needs it (e.g., XPS 9700).
+#   The kernel auto-selects the correct driver (0=auto, 3=SOF, 4=AVS) based on hardware IDs.
+#   Users can override at boot with "snd-intel-dspcfg.dsp_driver=3" if needed.
+#   See docs/KERNEL7_AUDIO_XPS9700.md for diagnostics.
+# • nvidia-drm.modeset=1: Required for nvidia GPU to use atomic mode-setting on Wayland (Niri).
+# • blacklist nouveau: nvidia GPU needs proprietary driver, not nouveau.
+# • btusb.enable_autosuspend=0: Prevent Bluetooth headset dropouts when idle.
 BOOT_CMDLINE="${BOOT_CMDLINE:-live.user=${LIVE_USER} console=tty0 console=ttyS0,115200 nvidia-drm.modeset=1 rd.driver.blacklist=nouveau modprobe.blacklist=nouveau btusb.enable_autosuspend=0}"
 
 echo ">>> running mklive.sh inside docker — output: $OUT_ISO"