The acpidump utility analyzes ACPI tables in physical memory and can dump them to a file. In addition, acpidump can call iasl(8) to disassemble AML (ACPI Machine Language) found in these tables and dump them as ASL (ACPI Source Language) to stdout.
ACPI tables have an essential data block (the DSDT, Differentiated System Description Table) that includes information used on the kernel side such as detailed information about PnP hardware, procedures for controlling power management support, and so on. The acpidump utility can extract the DSDT data block from physical memory and store it into an output file and optionally also disassemble it. If any Secondary System Description Table (SSDT) entries exist, they will also be included in the output file and disassembly.
When acpidump is invoked without the -f option, it will read ACPI tables from physical memory via /dev/mem. First it searches for the RSDP (Root System Description Pointer), which has the signature "RSD PTR ", and then gets the RSDT (Root System Description Table), which includes a list of pointers to physical memory addresses for other tables. The RSDT itself and all other tables linked from RSDT are generically called SDTs (System Description Tables) and their header has a common format which consists of items such as Signature, Length, Revision, Checksum, OEMID, OEM Table ID, OEM Revision, Creator ID and Creator Revision. When invoked with the -t flag, the acpidump utility dumps contents of the following tables: