feat(deck): Set kargs in yafti, matching SteamOS

system_files/deck/usr/share/ublue-os/firstboot/yafti.yml

@@ -172,6 +172,11 @@ screens:
           default: false
           packages:
           - Retrieve Greenlight: just get-greenlight
+        Kernel Arguments:
+          description: Sets kernel arguments used in SteamOS
+          default: true
+          packages:
+          - Set kargs: just set-steamos-kargs
         Memory Tuning:
           description: Adjust ZRAM and configure deckswap
           default: false

system_files/deck/usr/share/ublue-os/just/custom.just

@@ -1,3 +1,6 @@
+set-steamos-kargs:
+  rpm-ostree kargs --append="amd_iommu=off" --append="amdgpu.gttsize=8128" --append="spi_amd.speed_dev=1"
+
 create-steam-shortcuts:
   cp /usr/share/applications/steam.desktop ~/Desktop
   cp /etc/skel.d/Desktop/Return.desktop ~/Desktop