Use of contiguous physical memory in cxgbe driver

[Garrett Wollman]

<<On Wed, 12 Feb 2014 23:56:51 -0800, John-Mark Gurney <jmg at funkthat.com> said:

> Though we might want to keep a few mbufs reserved for receive now that
> you mention it...  We should never get to the point where we can't
> allocate even one frame for receive...

It's very easy to get to that state if the driver insists on getting
three physically contiguous pages (which is what it takes to allocate
a single 9k cluster)

-GAWollman