For FreeBSD, Intel has provided an interpreter (ACPI-CA) that is shared with Linux and NetBSD. The path to the ACPI-CA source code is src/sys/contrib/dev/acpica . The glue code that allows ACPI-CA to work on FreeBSD is in src/sys/dev/acpica/Osd . Finally, drivers that implement various ACPI devices are found in src/sys/dev/acpica.