v4plus: config.txt for passthrough

kvmd.install

@@ -83,6 +83,15 @@ post_upgrade() {
 			keyboxd@etc-pacman.d-gnupg.socket
 	fi
 
+	if [[ "$(varcmp "$2" 3.331)" -lt 0 ]]; then
+		grep -q "^dtoverlay=vc4-kms-v3d" /boot/config.txt || cat << EOF >> /boot/config.txt
+
+# Passthrough
+dtoverlay=vc4-kms-v3d
+disable_overscan=1
+EOF
+	fi
+
 	# Some update deletes /etc/motd, WTF
 	# shellcheck disable=SC2015,SC2166
 	[ ! -f /etc/motd -a -f /etc/motd.pacsave ] && mv /etc/motd.pacsave /etc/motd || true