Specifications

© 2008 Advanced Micro Devices Inc.
High Precision Event Timer (HPET)
AMD SB600 BIOS Developer’s Guide (Public Version) Proprietary
Page 45
12.2 ACPI HPET Description Table
As described in the specification, an ACPI HPET table is required to report the base address to the
operating system. The table includes a ACPI table header, and HPET table-specific fields. The sample
values for the HPET specific fields are as follows:
Event Timer Block ID DD 00000000h ;
Base Address (Lower 4 bytes) DD 00000800h ;
Base Address (Middle 4 bytes) DD 0FED00000h ; Address on 32 bit system
Base Address (Upper 4 bytes) DD 00000000h ; Used on 64 bit system
HPET Number DB 00h ;
Minimum Clock Tick DW 37EEh ; 14318 (decimal)
12.3 HPET Support for Longhorn
For the SB600, PM_IO register 72h bits [2:0] should be set to 111b for Longhorn support.