HT provides two System Management messages that can be used to report power management events to the host.
Message transmission may be stimulated by either hardware or software. A system that supports power management will very likely include a set of registers within the chipset (e.g., the South bridge or ICH) to support power management. For example, a chipset may give system software the ability to select which hardware events will cause the chipset to send a power management notification message to the Host Bridge. Similarly, software (e.g. ACPI software) may access a register, causing a power management to be sent. The actual entity responsible for sending these message to the Host Bridge is the System Management Controller (SMC). |