feat: NVIDIA fix for gaming mode (kernel parameters and early modules)

Untested on hardware; .no-release-yet keeps it out of the release.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

lib/nvidia.sh

@@ -0,0 +1,102 @@
+#!/bin/bash
+# NVIDIA fix for gaming mode, part of the SteamOS conversion
+# (gaming_enable/gaming_disable). gamescope drives the display itself
+# through DRM/KMS; with NVIDIA that needs kernel modesetting and the
+# framebuffer driver (nvidia-drm.modeset=1 nvidia-drm.fbdev=1) and the
+# driver in the initramfs, or the screen shows a corrupted image.
+# Does nothing without an NVIDIA GPU that has its driver installed.
+# Sourced by steamify.sh; not meant to be run on its own.
+
+NVIDIA_PARAMS="nvidia-drm.modeset=1 nvidia-drm.fbdev=1"
+NVIDIA_INITRAMFS_CONF=/etc/mkinitcpio.conf.d/90-steamify-nvidia.conf
+NVIDIA_MARK="# steamify-nvidia"
+
+nvidia_present() {
+    # An NVIDIA GPU (PCI vendor 0x10de, display class) and its kernel driver.
+    local d
+    for d in /sys/class/drm/card[0-9]*/device; do
+        [[ "$(cat "$d/vendor" 2>/dev/null)" == 0x10de ]] || continue
+        [[ "$(cat "$d/class" 2>/dev/null)" == 0x03* ]] && modinfo nvidia_drm >/dev/null 2>&1 && return 0
+    done
+    return 1
+}
+
+nvidia_boot_file() {
+    # Same boot loaders as the kernel command line elsewhere (lib/hdmi-refresh.sh).
+    hdmi_boot_file
+}
+
+nvidia_param_set() {
+    # 0 when $1 (e.g. nvidia-drm.modeset=1) is on the kernel command line or
+    # already in the boot loader's file (not booted yet).
+    local f; f="$(nvidia_boot_file)"
+    grep -qw -- "$1" /proc/cmdline 2>/dev/null ||
+        { [[ -n "$f" ]] && grep -qw -- "$1" "$f" 2>/dev/null; }
+}
+
+nvidia_params_missing() {
+    local p
+    for p in $NVIDIA_PARAMS; do nvidia_param_set "$p" || return 0; done
+    return 1
+}
+
+nvidia_initramfs_ok() {
+    [[ -f "$NVIDIA_INITRAMFS_CONF" ]] || grep -qE '^MODULES=.*nvidia_drm' /etc/mkinitcpio.conf 2>/dev/null
+}
+
+nvidia_rebuild_boot() {
+    local f; f="$(nvidia_boot_file)"
+    info "Rebuilding the initramfs and boot entries..."
+    case "$f" in
+        /etc/default/limine) sudo limine-mkinitcpio ;;
+        /etc/sdboot-manage.conf) sudo /usr/bin/mkinitcpio -P && sudo sdboot-manage gen ;;
+        /etc/default/grub) sudo /usr/bin/mkinitcpio -P && sudo grub-mkconfig -o /boot/grub/grub.cfg ;;
+        *) sudo /usr/bin/mkinitcpio -P ;;
+    esac
+}
+
+nvidia_enable() {
+    nvidia_present || return 0
+    local f changed=0 p; f="$(nvidia_boot_file)"
+    if nvidia_params_missing; then
+        if [[ -z "$f" ]]; then
+            warn "NVIDIA GPU found, but no supported boot loader: add '$NVIDIA_PARAMS' to the kernel command line yourself."
+        else
+            info "NVIDIA GPU found: adding $NVIDIA_PARAMS to the kernel command line (fixes a corrupted screen in gaming mode)..."
+            backup_file "$f"
+            case "$f" in
+                /etc/default/limine)
+                    printf 'KERNEL_CMDLINE[default]+=" %s" %s\n' "$NVIDIA_PARAMS" "$NVIDIA_MARK" | sudo tee -a "$f" >/dev/null ;;
+                /etc/sdboot-manage.conf)
+                    sudo sed -i -E "s/^(LINUX_OPTIONS=\"[^\"]*)\"/\1 $NVIDIA_PARAMS\"/" "$f" ;;
+                /etc/default/grub)
+                    sudo sed -i -E "s/^(GRUB_CMDLINE_LINUX_DEFAULT=\"[^\"]*)\"/\1 $NVIDIA_PARAMS\"/" "$f" ;;
+            esac
+            changed=1
+        fi
+    fi
+    if ! nvidia_initramfs_ok; then
+        info "Loading the NVIDIA modules early (initramfs)..."
+        printf 'MODULES+=(nvidia nvidia_modeset nvidia_uvm nvidia_drm)\n' |
+            sudo install -Dm644 /dev/stdin "$NVIDIA_INITRAMFS_CONF" && changed=1
+    fi
+    if [[ $changed == 1 ]]; then
+        nvidia_rebuild_boot || { err "Rebuilding the boot entries failed."; return 1; }
+        ok "NVIDIA gaming mode fix applied; it takes effect after a reboot."
+    fi
+    return 0
+}
+
+nvidia_disable() {
+    local f changed=0; f="$(nvidia_boot_file)"
+    if [[ -n "$f" ]] && grep -q "$NVIDIA_PARAMS" "$f" 2>/dev/null; then
+        case "$f" in
+            /etc/default/limine) sudo sed -i "/$NVIDIA_MARK\$/d" "$f" ;;
+            *) sudo sed -i "s/ \?$NVIDIA_PARAMS//" "$f" ;;
+        esac
+        changed=1
+    fi
+    [[ -f "$NVIDIA_INITRAMFS_CONF" ]] && { sudo rm -f "$NVIDIA_INITRAMFS_CONF"; changed=1; }
+    [[ $changed == 1 ]] && nvidia_rebuild_boot
+    return 0
+}