E1000_I2CCMD_SFP_DATA_ADDR
off = E1000_I2CCMD_SFP_DATA_ADDR(0);
E1000_I2CCMD_SFP_DATA_ADDR(E1000_SFF_IDENTIFIER_OFFSET),
E1000_I2CCMD_SFP_DATA_ADDR(E1000_SFF_ETH_FLAGS_OFFSET),