Reproducible igb related panic 11.0-ALPHA4

[Richard Perini]

On Mon, Jun 20, 2016 at 02:54:30PM +1000, Richard Perini wrote:
> 
> Reproducible igb related panic 11.0-ALPHA4 
> 
> OS: FreeBSD 11.0-ALPHA4 #6 r302022
> Hardware: Asus P9D C224 
> 	(integrated <Intel(R) PRO/1000 Network Connection, Version - 2.5.3-k)
> 
> 
> Hi,
> 
> Kernel panics within a few seconds with heavy network load. Using 
> "iperf -c another_host" is sufficient to induce the problem.  Setting
> hw.igb.enable_msix=0 in loader.conf "solves" the problem.  Below is the
> first few pages of crashinfo, + dmesg.  The problem occurs on 2 instances
> of similar hardware (with same motherboards). 

	Submitted as PR 210417 

--R