Bug 21400

Some time around or after August 3, any device other than ata assigned IRQ 15 
in a Compaq Proliant ML530 no longer works.

August 3: sym driver works with SCSI controller on IRQ 15

August 5: sym driver no longer attaches but ncr attaches instead to SCSI 
controller on IRQ 15

August 18: (dmesg output above) Neither sym/ncr nor fxp works on a device 
assigned IRQ 15.  There is an instant panic just after the sym driver 
attempts to attach to the SCSI controller while it is using IRQ 15 (doesn't 
even probe the rest of the devices or make it to a root mount attempt).  
Notice the presence of ata0, which is not supposed to exist on these 
systems.  Only ata1 is supposed to exist, if I recall correctly.  I will do 
some more investigative work by booting several earlier kernels and attempt 
to narrow down the exact problem date.  I've already done a minor amount by 
booting two previous kernels from the above dates and noting the results.

Fix: 

A temporary workaround is to lock all device resources down in the system 
configuration utility and keep them away from IRQ15.
How-To-Repeat: 
Boot a recent 4.1-STABLE kernel on a Compaq Proliant ML530 with a device other 
than ata assigned IRQ15.