Intel PCI User Manual

282

This register is applicable to the TBI mode/internal SerDes mode of operation. For internal PHY 
operation, program the register to 0000h. For example, clear this register in MMI mode.

This register has two meanings, depending on the state of Auto-Negotiation: one as the “AN 

advertise register” defined by IEEE 802.3z, and the other as a register for software control of the 

Auto-Negotiation process.

When performing hardware Auto-Negotiation, it fulfills the function defined by sub-clause 
37.3.6.1.3 of IEEE 802.3z.

1.

Not applicable to the 82541xx, 82547GI/EI, or 82540EP/EM.

A

Tx

Reserved

TxConfigWord

TxConfigWord

15:0

0b

Data transmitted during Auto-Negotiation process.
When performing hardware Auto-Negotiation (TXCW.ANE is 
set), the value of TxConfigWord is encoded as two 10-
bit symbols and sent as the “config_word” field for the /C/ 
ordered set. When the Ethernet controller performs software 
Auto-Negotiation, TxConfig and TxConfigWord are used to 
negotiate with the link partner. Data stored in TxConfigWord is 
transmitted during the Auto-Negotiation process. Software 
should not read back the contents of this field as content might 
change during the software Auto-Negotiation process. In the 
absence of loss of synchronization, the value read back is stable 
and equal to the value written.
The mapping of the TxConfigWord is as follows:

• TxConfigWord[15] Next page request
• TxConfigWord[14] Reserved (write as 0b; ignore on read)
• TxConfigWord[13:12] Remote fault indication
• TxConfigWord[11:9] Reserved (write as 0b; ignore on read)
• TxConfigWord[8:7] Pause
• TxConfigWord[6] Half-duplex 
• TxConfigWord[5] Full-duplex
• TxConfigWord[4:0] Reserved (write as 0b; ignore on read)

Bits 5,7 & 8 of TxConfigWord are loadable from the EEPROM 
upon power-up, or chip reset.

Reserved

29:16

0b

Reserved
Reads as 0b.
Should be written to 0b for future compatibility.