feat: VRAM booster for every supported GPU, not only the Steam Machine

lib/vram-booster.sh

@@ -1,9 +1,10 @@
 #!/bin/bash
-# "VRAM booster" menu item (vram), a sub-option of Steam Machine support
-# ticked along with it (opt-out), like SteamOS 3.9's dGPU VRAM management:
-# the game in front keeps its VRAM, background apps are evicted first, so a
-# game on the 8 GB GPU doesn't spill into system RAM and stutter. The kernel
-# side is the dmem cgroup controller (7.2); CachyOS packages the userspace
+# "VRAM booster" menu item (vram), ticked by default, like SteamOS 3.9's
+# dGPU VRAM management: the game in front keeps its VRAM, background apps
+# are evicted first, so a game that needs most of it doesn't spill into
+# system RAM and stutter. The kernel side is the dmem cgroup controller
+# (7.2; amdgpu and xe register their VRAM, NVIDIA's driver doesn't), so it's
+# only offered when the kernel lists a region. CachyOS packages the userspace
 # side: dmemcg-booster (a system service that enables the controller and
 # sets the limits, plus a user service) and plasma-foreground-booster, which
 # tells it which window is in front on the desktop. The latter only starts
@@ -12,6 +13,11 @@
 
 VRAM_PKGS=(dmemcg-booster plasma-foreground-booster)
 
+vram_available() {
+    # cgroupfs files have size 0, so read it.
+    grep -q . /sys/fs/cgroup/dmem.capacity 2>/dev/null || vram_status
+}
+
 vram_status() {
     pacman -Q "${VRAM_PKGS[@]}" >/dev/null 2>&1 &&
         systemctl is-enabled -q dmemcg-booster-system.service 2>/dev/null &&