I was using the ixgbe.ko version 1.3.31.5 for our Intel 82598 based NICs.
The driver uses the "TX head pointer write-back" feature of the chip in order to report the completion of it transmits.

We now moved to the 82599 based NICs and I upgraded the driver to v2.0.8-k2 in order to support this chip.
This driver does not use the "TX head pointer write-back" feature although the 82599 supports it. I've also modified the driver in order to see if this feature really works in th2 82599 and it seems to work.

My questions:
1. What was the reason for not using this feature in the new driver ?
2. Are there known with this feature (chip bug) ?
3. Are there known issues with this feature and HW platforms that needed
a rework of the driver ?

Thanks
Motih