Intel 82557 Benutzerhandbuch

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Note: This appendix applies only to the 82558 and subsequent devices.

Wake-up functionality was first introduced with the 82558 A-step. This component is capable of 

being brought out of a power managed stated by programming it to wake on reception of a packet 

addressed to it, a multicast or broadcast packet, any received packet, or a Magic Packet*. These 
wake-up capabilities are enabled through the Configuration Command bits.

This functionality was carried forward to the 82558 B-step and all subsequent Fast Ethernet 

devices. However, the wake on reception of a broadcast packet was changed to wake on reception 

of broadcasted ARP or VLAN ARP. The Configuration Command bits used to enable these wake-
up capabilities were also modified from the 82558 A-step. In addition, the 82558 B-step and all 

subsequent silicon also support the ability to wake on link status change.

If the device is enabled, it notifies the system of a wake-up packet event by asserting the PME# pin. 

The PME enable bit is located in the PMCSR. It is system responsibility to ensure that this bit is set 
only when the device is in the D1, D2, or D3 states (as required by the PCI Power Management 

Specification). After a wake-up event, the PME status bits in the PMCSR and CSR are set 

regardless of the value of the PME enable bit.

There are two types of wake-up events: reception of a wake-up packet and a link status event. The 
detection mechanism for wake-up packets (packet filtering) is further categorized by fixed packet 

filtering implemented by the hardware in the CSMA unit and flexible packet filtering implemented 

by the loadable microcode.

The device uses three different mechanisms to wake the system up:

1. Fixed packet wake up. This is implemented in hardware using the clock driven on the X1 pin.

2. Flexible packet filtering. This is implemented in the loadable microcode using the PCI CLK 

pin as clock. (The discussion of microcode is beyond the scope of this document.)

3. Link status change event.

The device is able to detect fixed packet and link status wake-up events to the system if power is 

supplied to the device. This may be the main PC power supply or an auxiliary power supply that is 
active whenever the system is plugged in.

The ability to use loadable microcode for flexible frame filtering requires a valid clock on the PCI 

CLK pin. This may be the CLK signal from the PCI bus or other valid clock signal connected to the 

device clock pin while the system is in low power mode.

The following table describes wake-up capabilities in different combinations of power supply and 
clock: