4.9 boot problem on em0 platform.

[Deepak Jain]

As a part of tracking down a performance issue, I tried building a 
custom kernel (with just IPFW, DUMMYNET added, NMBCLUSTERS, commenting 
out MATH_EMULATE, INET6, I386, I486). The system is currently running a 
kernel from a similar machine with the same settings.  The machine does 
run on this kernel:  4.9-RELEASE FreeBSD 4.9-RELEASE #8, with the above 
options, but I have not been able to compile a 4.9-RELEASE #2 (which is 
the source tree on the machine) kernel that has an identical config file.

So, when it builds itself from -RELEASE sources, it hangs at:

"pmap_mapdev: Couldn't alloc kernel virtual memory" I couldn't find a 
reference to anything recent. Nothing non-default (from a GENERIC 
kernel) with respect to ACPI has been touched. I see a reference to 
-CURRENT from 9/03, but that's it.

Should I turn off power management? Is there a way to prevent ACPI 
support from being loaded at the kernel level?

Should I just cvsup to 4.9-RELENG and try it again?

It would be very nice if this were some how related to my network 
performance problem, but that might be too much to hope for. :)

Thanks in advance,

DJ