feat: Opt-in BIOS update for the Steam Machine

- Menu item (Fremont only, never preselected) with the current and newest BIOS version.
- Two warnings and two confirmations (y/N, then typing UPDATE); checksum-verified download
  of Valve's fremont-hw-support; installed with fwupd, written at the next restart.
- Menu actions: one-off items that are never preselected, re-applied or listed as on/off.

AGENTS.md

@@ -132,6 +132,13 @@ gamescope and the Plasma desktop. Primary target: the Valve Steam Machine
   and `ensure-kernel-headers.service` installs missing ones at boot (a
   pacman hook can't run pacman), which triggers DKMS's install hook. The module creates
   `/sys/class/leds/valve-leds*`.
+- `bios` is an *action* (`ACTIONS` in `lib/menu.sh`), not an on/off
+  component: never preselected (not even on a first run), never re-applied
+  by `a`, not listed in the state overview, and `bios_status` is always off.
+  Keep both confirmations (y/N, then typing `UPDATE`) and the warnings; the
+  firmware comes from the newest `holo-X.Y` repo (`.files` db names the
+  `.cab`, `.db` gives the SHA-256), and fwupd itself refuses non-Fremont
+  hardware. It can only be tested up to fwupd's refusal in the VM.
 - `Relogin=true` means a gamescope that fails to start is relaunched in a
   tight loop; keep that in mind when changing session handling.
 

CHANGELOG.md

@@ -52,10 +52,16 @@ Machine LED driver works on every installed kernel and survives kernel updates.
   - Install with `.../releases/latest/download/setup-gamescope-boot.sh`, which
     always points to the newest release.
 - `1604ed1` **docs: Versioning and release rules in AGENTS.md**
-- **ci: The latest tag follows the newest version tag**
+- `6afef78` **ci: The latest tag follows the newest version tag**
   - When a new version is released, the `latest` tag and release move to it
     (bundle replaced), so the older `.../releases/download/latest/...` URL
     also always gives the newest version.
+- **feat: Opt-in BIOS update for the Steam Machine**
+  - New menu item (Steam Machine only, never ticked by default) showing the
+    current BIOS version and the newest from Valve's `fremont-hw-support`.
+  - Two large warnings and two confirmations (y/N, then typing `UPDATE`),
+    checksum-verified download, installed with fwupd; the wizard then offers
+    the restart that writes it, with a warning to keep the power on.
 
 ## 0.6.2 - 2026-09-23
 

README.md

@@ -283,17 +283,19 @@ cat /var/lib/dkms/leds-valve-dkms/0.1/build/make.log
 journalctl --user -b | grep -i led
 ```
 
-**BIOS updates** are not part of the wizard. Valve ships the Steam Machine
+**BIOS updates** (opt-in, never ticked by default). On a Steam Machine the menu
-BIOS as `F7F0108.cab` in its `fremont-hw-support` package for fwupd. To
+has an **Update BIOS** item that shows the current BIOS version and the newest
-install it by hand (keep the machine on mains power and don't interrupt it):
+one Valve ships (`F7F0108.cab` in its `fremont-hw-support` package, looked up
+on Valve's SteamOS mirror). Ticking it shows a large warning, asks for
+confirmation, shows the warning again and only continues when you type
+`UPDATE`. It then downloads the package (checksum verified) and hands the
+firmware to fwupd; the BIOS is written during the next restart.
 
-```bash
+**At your own risk:** a failed or interrupted BIOS update can leave the machine
-sudo dmidecode -s bios-version     # current version
+unable to start. Keep it on mains power, and never turn off the power, unplug
-sudo pacman -S fwupd
+it or press the power button while it updates, including during the restart
-curl -LO https://steamdeck-packages.steamos.cloud/archlinux-mirror/holo-3.9/os/x86_64/fremont-hw-support-20260807.1-1-any.pkg.tar.zst
+afterwards; the screen can stay black for several minutes. fwupd refuses the
-mkdir fhw && tar -I zstd -xf fremont-hw-support-*.pkg.tar.zst -C fhw
+file on anything that isn't a Steam Machine.
-sudo fwupdmgr install fhw/usr/share/fwupd/remotes.d/fremont/firmware/F7F0108.cab
-```
 
 ### Manual session control
 
@@ -328,6 +330,7 @@ gamescope-session, ...) stay installed.
 | `lib/vapor-theme.sh` | SteamOS theme: installs and switches to `cachyos-vapor` |
 | `lib/steamos-extras.sh` | SteamOS desktop extras from Valve's package (Add to Steam, Nested Desktop, icon, keyboard rule, KWallet) |
 | `lib/single-user.sh` | Single user mode: no lock screen, user switching or log out |
+| `lib/bios.sh` | Update BIOS (Steam Machine, opt-in): current/newest version, double confirmation, fwupd |
 | `lib/steam-machine.sh` | Steam Machine support: LED driver, LED access, steamos-manager |
 | `.github/tools/bundle.sh` | Builds the single-file version (`dist/setup-gamescope-boot.sh`) |
 | `.github/workflows/bundle.yml` | Builds and checks it on every push; publishes it on `main` |

lib/bios.sh

@@ -0,0 +1,121 @@
+#!/bin/bash
+# "Update BIOS" menu item, only on a Steam Machine and always opt-in: flashes
+# the newest Steam Machine BIOS from Valve's fremont-hw-support package with
+# fwupd. It's an action, not an on/off component: never preselected, never
+# re-applied, and there is nothing to turn off afterwards.
+# Sourced by setup-gamescope-boot.sh; not meant to be run on its own.
+
+BIOS_REPO_PREFIX=holo
+
+bios_available() { detect_valve_fremont; }
+
+bios_status() { return 1; }
+
+bios_disable() { return 0; }
+
+bios_current() {
+    cat /sys/class/dmi/id/bios_version 2>/dev/null || echo unknown
+}
+
+bios_lookup_newest() {
+    # Sets BIOS_REPO, BIOS_PKG, BIOS_SHA256 and BIOS_NEWEST (e.g. F7F0108)
+    # from the newest holo-X.Y repository on Valve's mirror: its .files
+    # database names the firmware file, its .db gives the package checksum.
+    # Only once per run, and with short timeouts so an offline machine
+    # doesn't hold up the menu.
+    [[ -n "${BIOS_LOOKED_UP:-}" ]] && return 0
+    BIOS_LOOKED_UP=1; BIOS_NEWEST=""
+    local tmp desc
+    BIOS_REPO="$(curl -fsL --max-time 10 "$VALVE_MIRROR/" | grep -oE "$BIOS_REPO_PREFIX-[0-9]+\.[0-9]+/" | tr -d / | sort -uV | tail -n 1)"
+    [[ -n "$BIOS_REPO" ]] || return 1
+    tmp="$(mktemp -d)"
+    if curl -fsL --max-time 30 "$VALVE_MIRROR/$BIOS_REPO/os/x86_64/$BIOS_REPO.files" -o "$tmp/files" &&
+        curl -fsL --max-time 30 "$VALVE_MIRROR/$BIOS_REPO/os/x86_64/$BIOS_REPO.db" -o "$tmp/db"; then
+        desc="$(tar -tf "$tmp/files" 2>/dev/null | grep -E '^fremont-hw-support-[0-9][^/]*/files$' | head -n 1)"
+        [[ -n "$desc" ]] && BIOS_CAB="$(tar -xOf "$tmp/files" "$desc" | grep -E '^usr/share/fwupd/.*\.cab$' | head -n 1)"
+        desc="${desc%/files}/desc"
+        BIOS_PKG="$(tar -xOf "$tmp/db" "$desc" 2>/dev/null | awk '/^%FILENAME%$/ { getline; print }')"
+        BIOS_SHA256="$(tar -xOf "$tmp/db" "$desc" 2>/dev/null | awk '/^%SHA256SUM%$/ { getline; print }')"
+        [[ -n "${BIOS_CAB:-}" && -n "$BIOS_PKG" && -n "$BIOS_SHA256" ]] && BIOS_NEWEST="$(basename "$BIOS_CAB" .cab)"
+    fi
+    rm -rf "$tmp"
+    [[ -n "$BIOS_NEWEST" ]]
+}
+
+bios_label() {
+    # Menu label with the current and the newest version.
+    local newest="newest unknown (offline?)"
+    bios_lookup_newest && newest="newest $BIOS_NEWEST"
+    [[ "$BIOS_NEWEST" == "$(bios_current)" ]] && newest="up to date"
+    echo "Update BIOS (at your own risk): now $(bios_current), $newest"
+}
+
+bios_disclaimer() {
+    local r="$c_red$c_bold" n="$c_reset"
+    echo
+    echo -e "${r}  ###################################################################${n}"
+    echo -e "${r}  ##                                                               ##${n}"
+    echo -e "${r}  ##    WARNING: BIOS UPDATE - ENTIRELY AT YOUR OWN RISK           ##${n}"
+    echo -e "${r}  ##                                                               ##${n}"
+    echo -e "${r}  ###################################################################${n}"
+    echo -e "${r}  ##${n}  $1"
+    echo -e "${r}  ##${n}"
+    echo -e "${r}  ##${n}  - A failed or interrupted BIOS update can leave the machine"
+    echo -e "${r}  ##${n}    unable to start (bricked). This wizard, CachyOS and Valve"
+    echo -e "${r}  ##${n}    take no responsibility for that."
+    echo -e "${r}  ##${n}  - ${c_bold}NEVER turn off the power, unplug the machine or press the${n}"
+    echo -e "${r}  ##${n}    ${c_bold}power button while the update runs${n}, including during the"
+    echo -e "${r}  ##${n}    restart(s) afterwards, when the firmware is actually written."
+    echo -e "${r}  ##${n}  - The screen can stay black for several minutes. Wait."
+    echo -e "${r}  ##${n}  - Use this only on a Valve Steam Machine, on mains power, and"
+    echo -e "${r}  ##${n}    close all other programs first."
+    echo -e "${r}  ###################################################################${n}"
+    echo
+}
+
+bios_enable() {
+    if ! bios_lookup_newest; then
+        err "Couldn't find the newest Steam Machine BIOS on Valve's mirror ($VALVE_MIRROR)."
+        return 1
+    fi
+    local current
+    current="$(bios_current)"
+    if [[ "$current" == "$BIOS_NEWEST" ]]; then
+        ok "The BIOS is already the newest version ($current); nothing to do."
+        return 0
+    fi
+
+    bios_disclaimer "Current BIOS: ${c_bold}$current${c_reset}   ->   new BIOS: ${c_bold}$BIOS_NEWEST${c_reset} ($BIOS_PKG)"
+    ask_yn "Do you understand the risks and want to continue?" n ||
+        { info "BIOS update cancelled; nothing was changed."; return 0; }
+    bios_disclaimer "LAST CHANCE: this flashes BIOS $BIOS_NEWEST onto this machine."
+    local reply
+    read -rp "$(echo -e "${c_red}${c_bold}Type UPDATE (in capitals) to flash the BIOS, anything else cancels:${c_reset} ")" reply
+    [[ "$reply" == UPDATE ]] || { info "BIOS update cancelled; nothing was changed."; return 0; }
+
+    pacman -Q fwupd >/dev/null 2>&1 || sudo pacman -S --needed --noconfirm fwupd ||
+        { err "Installing fwupd failed."; return 1; }
+    local tmp
+    tmp="$(mktemp -d)"
+    info "Downloading $BIOS_PKG ($BIOS_REPO)..."
+    if ! curl -fL "$VALVE_MIRROR/$BIOS_REPO/os/x86_64/$BIOS_PKG" -o "$tmp/pkg.tar.zst" ||
+        ! echo "$BIOS_SHA256  $tmp/pkg.tar.zst" | sha256sum -c --quiet - ||
+        ! tar -I unzstd -xf "$tmp/pkg.tar.zst" -C "$tmp" "$BIOS_CAB"; then
+        err "Downloading or verifying $BIOS_PKG failed; the BIOS was not touched."
+        rm -rf "$tmp"
+        return 1
+    fi
+
+    info "Handing BIOS $BIOS_NEWEST to fwupd. Do NOT turn off the power from now on."
+    # -y: we already asked twice; --no-reboot-check: the wizard's own
+    # restart question comes at the end.
+    if ! sudo fwupdmgr install -y --no-reboot-check "$tmp/$BIOS_CAB"; then
+        err "fwupd could not install the BIOS update (see above); the BIOS was not changed."
+        rm -rf "$tmp"
+        return 1
+    fi
+    rm -rf "$tmp"
+    BIOS_NEEDS_RESTART=1
+    ok "BIOS $BIOS_NEWEST is staged. It is written during the next restart:"
+    warn "keep the power on and don't touch the machine until it has fully started again."
+}

lib/menu.sh

@@ -5,7 +5,10 @@
 
 # Menu order. Components are turned on in this order and off in reverse;
 # gaming must come first (single user builds on it).
-COMPONENTS=(gaming theme glyphs single machine)
+COMPONENTS=(gaming theme glyphs single machine bios)
+# One-off actions rather than on/off components: never preselected, never
+# re-applied, not listed as on or off.
+ACTIONS=(bios)
 
 declare -A LABEL=(
     [gaming]="SteamOS conversion: boot into gaming mode, Steam on the desktop"
@@ -13,13 +16,19 @@ declare -A LABEL=(
     [glyphs]="Install Steam Deck/Machine icons: Deck button icons in gaming mode"
     [single]="Single user mode: no password, lock screen or log out (SDDM)"
     [machine]="Steam Machine support: LED bar driver, hardware settings in Steam"
+    [bios]="Update BIOS"
 )
 declare -A CURRENT WANTED
 
 component_available() {
-    [[ "$1" != machine ]] || machine_available
+    case "$1" in
+        machine) machine_available ;;
+        bios) bios_available ;;
+    esac
 }
 
+is_action() { [[ " ${ACTIONS[*]} " == *" $1 "* ]]; }
+
 detect_components() {
     local c any=false
     for c in "${COMPONENTS[@]}"; do
@@ -27,10 +36,12 @@ detect_components() {
         if "${c}_status"; then CURRENT[$c]=1; any=true; else CURRENT[$c]=0; fi
         WANTED[$c]=${CURRENT[$c]}
     done
-    # First run: preselect the full SteamOS experience.
+    # Shows the current and newest BIOS version.
+    bios_available && { bios_lookup_newest; LABEL[bios]="$(bios_label)"; }
+    # First run: preselect the full SteamOS experience (never an action).
     if [[ "$any" == false ]]; then
         for c in "${COMPONENTS[@]}"; do
-            component_available "$c" && WANTED[$c]=1
+            component_available "$c" && ! is_action "$c" && WANTED[$c]=1
         done
     fi
 }
@@ -52,6 +63,7 @@ show_menu() {
         component_available "$c" || continue
         i=$((i + 1)); MENU_ITEMS[$i]=$c
         now="off"; [[ "${CURRENT[$c]}" == 1 ]] && now="${c_green}on${c_reset} "
+        is_action "$c" && now="-"
         want="[ ]"; [[ "${WANTED[$c]}" == 1 ]] && want="[x]"
         printf "  %-3s %-6b %-6s %s\n" "$i" "$now  " "$want" "${LABEL[$c]}"
     done
@@ -84,13 +96,14 @@ draw_menu_tui() {
         component_available "$c" || continue
         MENU_ITEMS[$i]=$c
         box="[ ]"; [[ "${WANTED[$c]}" == 1 ]] && box="[${c_green}x${c_reset}]"
-        state="off"; [[ "${CURRENT[$c]}" == 1 ]] && state="${c_green}on${c_reset}"
+        state="  (now: off)"; [[ "${CURRENT[$c]}" == 1 ]] && state="  (now: ${c_green}on${c_reset})"
+        is_action "$c" && state="  (opt-in, runs once)"
         line="$box ${LABEL[$c]}"
         if (( i == cursor )); then
             # The green x's reset would end the bold too: re-enable it after.
-            echo -e " ${c_cyan}>${c_reset} ${c_bold}${line//"$c_reset"/"$c_reset$c_bold"}${c_reset}  (now: ${state})"
+            echo -e " ${c_cyan}>${c_reset} ${c_bold}${line//"$c_reset"/"$c_reset$c_bold"}${c_reset}${state}"
         else
-            echo -e "   ${line}  (now: ${state})"
+            echo -e "   ${line}${state}"
         fi
         i=$((i + 1))
     done
@@ -160,6 +173,7 @@ plan_changes() {
     for c in "${COMPONENTS[@]}"; do
         component_available "$c" || continue
         [[ "${WANTED[$c]}" == 1 ]] || continue
+        if is_action "$c"; then TO_ENABLE+=("$c"); continue; fi
         if [[ "${CURRENT[$c]}" == 0 || "$REAPPLY" == true ]] ||
             [[ "$c" == gaming && "${CURRENT[single]}" != "${WANTED[single]}" ]]; then
             TO_ENABLE+=("$c")
@@ -177,7 +191,8 @@ apply_changes() {
         "${c}_disable" || failed+=("$c")
     done
     for c in "${TO_ENABLE[@]}"; do
-        echo; echo -e "${c_bold}Turning on: ${LABEL[$c]}${c_reset}"
+        if is_action "$c"; then echo; echo -e "${c_bold}Running: ${LABEL[$c]}${c_reset}"
+        else echo; echo -e "${c_bold}Turning on: ${LABEL[$c]}${c_reset}"; fi
         "${c}_enable" || failed+=("$c")
     done
     FAILED=("${failed[@]}")

setup-gamescope-boot.sh

@@ -19,7 +19,7 @@ VERSION=0.7.0
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
-for lib in common state packages login-manager single-user steam-desktop steam-machine vapor-theme steamos-extras desktop-shortcut menu; do
+for lib in common state packages login-manager single-user steam-desktop steam-machine vapor-theme steamos-extras bios desktop-shortcut menu; do
     # shellcheck source=/dev/null
     source "$SCRIPT_DIR/lib/$lib.sh"
 done
@@ -52,7 +52,8 @@ echo
 echo -e "${c_bold}This will:${c_reset}"
 for c in "${TO_DISABLE[@]}"; do echo "  - turn off: ${LABEL[$c]}"; done
 for c in "${TO_ENABLE[@]}"; do
-    if [[ "${CURRENT[$c]}" == 1 ]]; then echo "  - re-apply: ${LABEL[$c]}"; else echo "  - turn on:  ${LABEL[$c]}"; fi
+    if is_action "$c"; then echo "  - run:      ${LABEL[$c]} (asks two more confirmations)"
+    elif [[ "${CURRENT[$c]}" == 1 ]]; then echo "  - re-apply: ${LABEL[$c]}"; else echo "  - turn on:  ${LABEL[$c]}"; fi
 done
 ask_yn "Go ahead?" y || { info "Nothing changed."; exit 0; }
 
@@ -67,7 +68,7 @@ echo
 detect_components
 echo -e "${c_bold}Done. Current state:${c_reset}"
 for c in "${COMPONENTS[@]}"; do
-    component_available "$c" || continue
+    component_available "$c" && ! is_action "$c" || continue
     if [[ "${CURRENT[$c]}" == 1 ]]; then echo -e "  ${c_green}on ${c_reset} ${LABEL[$c]}"; else echo "  off  ${LABEL[$c]}"; fi
 done
 if [[ ${#FAILED[@]} -gt 0 ]]; then
@@ -75,6 +76,18 @@ if [[ ${#FAILED[@]} -gt 0 ]]; then
 fi
 echo
 
+# A staged BIOS update is written during the restart.
+if [[ -n "${BIOS_NEEDS_RESTART:-}" ]]; then
+    warn "The BIOS update is written during the next restart. Keep the power on and"
+    warn "don't touch the machine until it has fully started again, even if the screen stays black."
+    if ask_yn "Restart now to install the BIOS update?" n; then
+        sudo reboot
+    else
+        info "The BIOS update installs at your next restart."
+    fi
+    exit 0
+fi
+
 # Login manager changes only take effect after a restart.
 if [[ " ${TO_DISABLE[*]} ${TO_ENABLE[*]} " == *" gaming "* || " ${TO_DISABLE[*]} ${TO_ENABLE[*]} " == *" single "* ]]; then
     if ask_yn "Restart now so the changes take effect?" n; then