feat: VRAM booster greyed out with an NVIDIA card, with why

lib/menu.sh

@@ -109,7 +109,7 @@ feature_new() {
     # conversion as its parent): never turned on or off.
     local p="${PARENT[$1]:-gaming}"
     [[ "$1" != gaming && "${CURRENT[$p]:-0}" == 1 && "${CURRENT[$1]:-0}" == 0 ]] &&
-        ! is_action "$1" && [[ " ${NO_PRESELECT[*]} " != *" $1 "* ]] &&
+        ! is_action "$1" && component_selectable "$1" && [[ " ${NO_PRESELECT[*]} " != *" $1 "* ]] &&
         [[ -z "$(state_get features "$1")" ]]
 }
 
@@ -117,6 +117,7 @@ component_selectable() {
     # Greyed out and not tickable when it has nothing to do.
     case "$1" in
         bios) bios_selectable ;;
+        vram) vram_selectable ;;
     esac
 }
 
@@ -145,10 +146,12 @@ detect_components() {
     launcher_repair && WANTED[launcher]=1
     # Shows the current and newest BIOS version.
     bios_available && { bios_lookup_newest; LABEL[bios]="$(bios_label)"; }
+    # Greyed out with an NVIDIA card: say why.
+    component_available vram && ! vram_selectable && LABEL[vram]="VRAM booster: not supported by NVIDIA's driver yet"
     # First run: preselect the full SteamOS experience (never an action).
     if [[ "$any" == false ]]; then
         for c in "${COMPONENTS[@]}"; do
-            component_available "$c" && ! is_action "$c" &&
+            component_available "$c" && component_selectable "$c" && ! is_action "$c" &&
                 [[ " ${NO_PRESELECT[*]} " != *" $c "* ]] && WANTED[$c]=1
         done
         machine_available && WANTED[cec]=1

lib/vram-booster.sh

@@ -14,13 +14,31 @@
 VRAM_PKGS=(dmemcg-booster plasma-foreground-booster)
 VRAM_MIN_BYTES=$((2 * 1024 * 1024 * 1024))
 
-vram_available() {
+vram_supported() {
+    # WIZARD_VRAM_FAKE_NVIDIA=1 (tests): as with an NVIDIA card.
+    [[ -n "${WIZARD_VRAM_FAKE_NVIDIA:-}" ]] && return 1
     # Only for a GPU with its own VRAM: an integrated GPU registers a small
     # carve-out too, but mostly uses system RAM, so there's little to boost.
     awk -v min="$VRAM_MIN_BYTES" '$1 ~ /\/vram$/ && $2 >= min { found = 1 } END { exit !found }' \
-        /sys/fs/cgroup/dmem.capacity 2>/dev/null || vram_status
+        /sys/fs/cgroup/dmem.capacity 2>/dev/null
 }
 
+vram_nvidia() {
+    # An NVIDIA display controller (PCI vendor 10de, class 03xxxx).
+    local d
+    [[ -n "${WIZARD_VRAM_FAKE_NVIDIA:-}" ]] && return 0
+    for d in /sys/bus/pci/devices/*; do
+        [[ "$(cat "$d/vendor" 2>/dev/null)" == 0x10de && "$(cat "$d/class" 2>/dev/null)" == 0x03* ]] && return 0
+    done
+    return 1
+}
+
+# Shown where it works, and greyed out with an NVIDIA card, whose driver
+# doesn't register its VRAM with the kernel (yet): so it's clear why it
+# can't be turned on. Hidden elsewhere (integrated graphics, older kernel).
+vram_available() { vram_supported || vram_status || vram_nvidia; }
+vram_selectable() { vram_supported || vram_status; }
+
 vram_status() {
     pacman -Q "${VRAM_PKGS[@]}" >/dev/null 2>&1 &&
         systemctl is-enabled -q dmemcg-booster-system.service 2>/dev/null &&