---
name: "acpidump"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/acpidump/8"
---

# acpidump(8)

dump ACPI tables and ASL

## NAME

**acpidump** – dump ACPI tables and ASL

## SYNOPSIS

**acpidump** \[**-d**\] \[**-f** *dsdt\_input*\] \[**-h**\] \[**-o** *dsdt\_output*\] \[**-t**\] \[**-T** *table\_name*\] \[**-v**\]

## DESCRIPTION

The **acpidump** utility analyzes ACPI tables in physical memory and can dump them to a file. In addition, **acpidump** can call [iasl(8)](/iasl/8.md) 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 all the ACPI tables, except the DSDT and SSDT. The following SDTs are reported in detail, while the remainder will only report the common header information:

- BERT Boot Error Record Table

  Reports any previous boot errors.

- DMAR DMA Remapping Table

  Contains information about the DMA remapping necessary for the system for I/O virtualization on Intel CPUS.

- DSDT Differentiated System Description Table

  Contains the main AML for the system.

- ECDT Embedded Controller Boot Resources Table

  Contains information about accessing the embedded controller prior to the OS decoding the DSDT for all its details.

- EINJ Error Injection Table

  Use to inject hardware errors to the error reporting mechanisms.

- ERST Error Record Serialization Table

  Information to retrieve and manage errors reported from the hardware.

- FACS Firmware ACPI Control Structure

  Information for the OS to interact with the firmware for things like suspend / resume and prevent mutual access to resources shared between the OS and the firmware.

- FACP Fixed ACPI Description Table (FADT)

  Information related to power management, and other CPU related data.

- HEST Hardware Error Source Table

  Describes the possible sources of hardware errors to the OS.

- HPET High Precision Event Timer Table

  Describes the high precision timers in the system.

- IVRS I/O Virtualization Reporting Structure

  Information for hypvervisors to use to share I/O resources on AMD processors.

- LPIT Low Power Idle Table

  Power management information for reducing power usage of the system.

- MADT Multiple APIC Description Table

  Describes all the Advanced Programmable Interrupt Controllers and Intel Streamlined Advanced Programmable Interrupt Controller present in the system.

- MCFG PCI Express Memory-mapped Configuration

  PCI config space base address register.

- MSDM Microsoft Data Management Table

  Contains the Microsoft software licensing data, including the product key embedded in firmware by the OEM.

- NFIT NVDIMM Firmware Interface Table

  NVDIMM information in the system.

- RSD PTR

  Pointer to the RSDT.

- RSDT Root System Description Table

  An array of physical pointers to other system description tables, the FACP (Fixed ACPI Description Table).

- SLIT System Locality Distance Information Table

  Provides information about the cost of communicating between different parts of the system (NUMA).

- SPCR Serial Port Console Redirection

  Contains informatiom about any serial port that the firmware used as a reporting console.

- SRAT System Resource Affinity Table

  Defines the domains of locality in the system for processors, memory and generic initiators (eg PCIe root complexes).

- TCPA Trusted Computing Platform Alliance

  Information about the TPM elements of the system.

- TPM2 Trusted Platform Module 2

  Additional information about newer TPM hardware.

- WDDT Watchdog Timer Description Table

  Information about how to manage watchdog timers in the system.

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.

## OPTIONS

The following options are supported by **acpidump**:

- **-d**

  Concatenate the DSDT and the SSDT's into single image and disassemble the image into ASL using [iasl(8)](/iasl/8.md) and print the results to stdout.

- **-t**

  Dump the contents of the various fixed tables listed above.

- **-T** *table\_name*

  Dump the contents of the specific table. All ACPI tables are exactly 4 characters long.

- **-h**

  Displays usage and exit.

- **-s**

  Disassemble each of the DSDT and the SSDT's into ASL using [iasl(8)](/iasl/8.md) and print the results to stdout. This will avoid [iasl(8)](/iasl/8.md) error on disassembling concatenated image. If both **-d** and **-s** are specified, the last option is effective.

- **-v**

  Enable verbose messages.

- **-f** *dsdt\_input*

  Load the DSDT from the specified file instead of physical memory. Since only the DSDT is stored in the file, the **-t** flag may not be used with this option.

- **-o** *dsdt\_output*

  Store the DSDT data block from physical memory into the specified file.

## FILES

- */dev/mem*

  ## EXAMPLES

If a developer requests a copy of your ASL, please use the following command to dump all tables and compress the result.

```
# acpidump -dt | gzip -c9 > my_computer.asl.gz
```

This example dumps the DSDT from physical memory to foo.dsdt. It also prints the contents of various system tables and disassembles the AML contained in the DSDT to stdout, redirecting the output to foo.asl.

```
# acpidump -t -d -o foo.dsdt > foo.asl
```

This example reads a DSDT file and disassembles it to stdout. Verbose messages are enabled.

```
# acpidump -v -d -f foo.dsdt
```

## SEE ALSO

[acpi(4)](/acpi/4.md), [mem(4)](/mem/4.md), [acpiconf(8)](/acpiconf/8.md), [acpidb(8)](/acpidb/8.md), [iasl(8)](/iasl/8.md)

## HISTORY

The **acpidump** utility first appeared in FreeBSD 5.0 and was rewritten to use [iasl(8)](/iasl/8.md) for FreeBSD 5.2.

## AUTHORS

Doug Rabson ⟨*dfr@FreeBSD.org*⟩ Mitsuru IWASAKI ⟨*iwasaki@FreeBSD.org*⟩ Yasuo YOKOYAMA ⟨*yokoyama@jp.FreeBSD.org*⟩ Nate Lawson ⟨*njl@FreeBSD.org*⟩

Some contributions made by Chitoshi Ohsawa ⟨*ohsawa@catv1.ccn-net.ne.jp*⟩, Takayasu IWANASHI ⟨*takayasu@wendy.a.perfect-liberty.or.jp*⟩, Yoshihiko SARUMARU ⟨*mistral@imasy.or.jp*⟩, Hiroki Sato ⟨*hrs@FreeBSD.org*⟩, Michael Lucas ⟨*mwlucas@blackhelicopters.org*⟩ and Michael Smith ⟨*msmith@FreeBSD.org*⟩.

## BUGS

The current implementation does not dump the BOOT structure or other miscellaneous tables.