FWIW: that DSDT hack is replacing a constant return value from the first method in the &quot;HAD&quot; device.  It was specified to return 0, but now returns 0xf instead.  This is almost certainly the _STA (status) method, which informs the OS about the operational status of the described device.  I forget the exact meaning of the bottom four bits offhand, but 0xf is the standard value for &quot;device present and operating normally -- use it!&quot;.<p>That it was returning zero would cause the linux ACPI framework to ignore it and not probe its driver.  My vague understanding is that windows works differently, and calling _STA is done by the driver, so it&#x27;s possible to just not do it and still have a working system.<p>I don&#x27;t know what the device itself is, but given that the script says &quot;audio&quot; in there it&#x27;s probably the audio codec.