Chipset to enable WakeOnLAN on unexpected power-off
Original Publication Date: 2004-May-27
Included in the Prior Art Database: 2004-May-27
ACPI Chipset Design to Enable Wake-On-LAN on Unexpected Power-Off
Chipset to enable WakeOnLAN on unexpected power -off
Disclosed is an ACPI compliant chipset which has a logic to detect unexpected power-off condition and reset a network controller in order to enable Wake-On-LAN.
Wake-On-LAN is a technology that allows a computer system to wake from powered-off state or sleep state upon receiving a specially formatted packet of information via a network interface. Currently Wake-On-LAN has been implemented in most PCs, but it may not work if a computer is unexpectedly turned off. Network controllers (e.g. Ethernet) have device specific registers, such as a wake-up packet pattern matching register, which need to be configured to respond a wake-up packet. The register can be initialized by the network controller's power-on-reset, or set by a device driver for the network controller. In general, BIOS code does not know how to configure the network controller's device specific registers.
If a system is shut down properly, OS, device drivers and BIOS will re-arm the Wake-On-LAN circuitry by properly initializing all register values to allow the next wake event, and a remote administrator can cause the sleeping system to power up on demand. However, if the computer is unexpectedly turned off, the network controller may not be ready to respond to a wake-up packet. For example, the wake-up pattern matching register may not be correctly set, the network interface may have PME# signal generation disabled. The computer may be unexpectedly turned off in a manner that defeats the Wake-On-LAN capability, for example, a service processor is used to remove power after a hang operating system condition. Not being able to wake the system is a problem for system administrators because it may require an expensive trip to a remote computer system in order to correct a problem that otherwise could have been handled from a central location.