I was looking at Chelsio NICs and there were mentions of Netmap support. Do you know what it means for a NIC to support Netmap vs one that doesnt? Is it an extra optimization/fast-path?
Can't give a good technical answer to that. But I suspect that it should be a matter of driver mostly. When you mmap /dev/netmap from userland, the OS TCP/IP stack is disconnected and you get access to the card tx/rx rings. Obviously the driver has to facilitate this.