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122 Software Developer’s Manual
EEPROM Interface
5.6.35 Checksum Word Calculation (Word 3Fh)
The Checksum word (3Fh) should be calculated such that after adding all the words (00h-3Fh),
including the Checksum word itself, the sum should be BABAh. The initial value in the 16-bit
summing register should be 0000h and the carry bit should be ignored after each addition. This
checksum is not accessed by the Ethernet controller. If CRC checking is required, it must be
performed by software.
Note: Hardware does not calculate checksum word 3Fh during EEPROM write; it must be calculated by
software independently and included in the EEPROM write data. Hardware does not compute a
checksum over words 00h-0Fh during EEPROM reads in order to determine the validity of the
EEPROM image; this field is provided strictly for software verification of EEPROM validity. All
hardware configuration based on word 00h-0Fh content is based on the validity of the Signature
field of EEPROM Initialization Control Word 1. Signature must be 01b.
5.6.36 82546GB/EB Dual-Channel Fiber Wake on LAN (WOL) Mode
and Functionality (Word 0Ah, 20h)
Four bits and two words determine dual-channel fiber WOL mode and functionality. In addition to
the power management bits, one of the SDP’s must be set in order for the “A” laser to remain on
when the system goes into D3. Three states are defined for the EEPROM image:
• Never - The Ethernet controller has WOL disabled and cannot be put into WOL mode.
• Possible - The Ethernet controller can be WOL enabled, but currently has the feature turned
off. This is the normal shipping configuration for WOL-capable server adapter cards.
• On - The Ethernet controller is set with WOL functionality enabled.
5.6.37 EEPROM Images
Refer to the appropriate Ethernet controller’s EEPROM map and programming information for
sample EEPROM images.
Table 5-19. WOL Mode and Functionality (Word 0Ah)
State Bit 2 Bit 7 Resulting Word
Never 0 0 4C03
Possible 1 0 4C0B
On 1 1 4C2B
Table 5-20. WOL Mode and Functionality (Word 20h)
State Bit 2 Bit 7 Resulting Word
Never 0 0 C109
Possible 1 0 C10D
On 1 1 C18D