[omgtehlion]

Yes it is. In hft (or any algo trading nowadays) it is commonplace to use usermode networking since like ~2010 or even earlier.

The part of NICs address space is mapped to a process (control registers and memory rings), and whole driver just runs in your process without going through the kernel. Of course, it ignores usual stuff like firewalls, iptables, etc, but who cares when all you need is the lowest latency possible )