em revision 7.0.0:
- Using driver devclass, seperate legacy (pre-pcie) code
into a seperate source file. This will at least help
protect against regression issues. It compiles along
with em, and is transparent to end use, devices in each
appear to be 'emX'. When using em in a modular form this
also allows the legacy stuff to be defined out.
- Add tx and rx rings as in igb, in the 82574 this becomes
actual multiqueue for the first time (2 queues) while in
other PCIE adapters its just make code cleaner.
- Add RX mbuf handling logic that matches igb, this will
eliminate packet drops due to temporary mbuf shortage.
igb revision 1.9.3:
- Following the ixgbe code, use a new approach in what
was called 'get_buf', the routine now has been made
independent of rxeof, it now does the update to the
engine TDT register, this design allows temporary
mbuf resources to become non-critical, not requiring
a packet to be discarded, instead it just returns and
does not increment the tail pointer.
- With the above change it was also unnecessary to keep
'spare' maps around, since we do not have the discard
issue.
- Performance tweaks and improvements to the code also.
MFC in a week
