Manual Pages  — ACPIDUMP

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 amp;", 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:

BERT DMAR DSDT ECDT EINJ ERST FACS FADT HEST HPET LPIT MADT MCFG NFIT RSD PTR RSDT SLIT SRAT TCPA TPM2 WDDT

The RSDT contains a pointer to the physical memory address of the FACP (Fixed ACPI Description Table). The FACP defines static system information about power management support (ACPI Hardware Register Implementation) such as interrupt mode (INT_MODEL), SCI interrupt number, SMI command port (SMI_CMD) and the location of ACPI registers. The FACP also has a pointer to a physical memory address for the DSDT. While the other tables are fixed format, the DSDT consists of free-formatted AML data.