The BIOS for the Broadwell platform has an OS detection mechanism that hides ACPI-enumerated hardware if the OS reports itself as other than Windows. This feature adds the needed OSI string to the acpi default supported interfaces. See upstream commit faae404e for details. Done in kernel v3.15-rc1 commit faae404ebdc6bba744919d82e64c16448eb24a36 ACPICA: Add "Windows 2013" string to _OSI support.