Based on Uefi/UefiAcpiDataTable.h, original notice:
UEFI ACPI Data Table Definition.
Copyright (c) 2011, Intel Corporation. All rights reserved. This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License that accompanies this distribution. The full text of the license may be found at http://opensource.org/licenses/bsd-license.php.
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
To avoid confusion in interpreting frames, the communication buffer should always begin with EFI_SMM_COMMUNICATE_HEADER