ACPICA: Difference between revisions

Note: The ACPI specification is highly portable specification, however, it has a static part which is generally non-portable: the location of the Root System Descriptor Pointer. This pointer may be found in many different ways depending on the chipset. On PC-compatible computers (without EFI) it is located in lower memory generally somewhere between 0x80000 and 0x100000. However, even within the PC compatible platform, an EFI-enabled board will export the RSDP to the OS on when it loads it through the EFI system tables. Other boards on server machines which are not PC-compatibles, like IBM blades,embedded and handheld devices which implement ACPI will again, not all be expected to position the RSDP in the same place as any other board. The RSDP is therefore located in a chipset-specific manner; From the time the OS has the RSDP, the rest of ACPI is completely portable. However, the way the RSDP is found is not. This would be the reason that the ACPICA code wouldn't try to provide routines to expressly find the RSDP in a portable manner.