x86/generic: add xen DomU support

Copy the relevant config options from the xen_domu subtarget

Signed-off-by: Felix Fietkau <nbd@nbd.name>

target/linux/x86/generic/base-files/lib/preinit/45_mount_xenfs

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Copyright (C) 2010 OpenWrt.org
+
+do_mount_xenfs() {
+	grep -q xenfs /proc/filesystems && \
+		mount -o noatime -t xenfs none /proc/xen
+}
+
+boot_hook_add preinit_mount_root do_mount_xenfs