I've been trying to cross build NetBSD-current using Interix (Windows 
Services for UNIX).  Its important to some of our embedded customers to be 
able to work in Windows since there is a lot of good EDA software that only 
runs on Windows (IDE's for FPGA programming, PCB/schematic capture, etc.) 
I've run into a few problems so far:

* cc did not work for bootstrapping nbmake.. had to use HOST_CC="gcc"
* many missing declarations unless #define _ALL_SOURCE, had to add both 
"HOST_CPPFLAGS=-D_ALL_SOURCE" and "CPPFLAGS=-D_ALL_SOURCE" since 
HOST_CPPFLAGS seemed to be used only on the nbmake build
* missing zlib..  installed pkg from Interopsystems, but installed it in 
/usr/local/[include,lib] so just cp'ed to /usr/include
* missing sys/mtio.h header for tools/compat..  removed from configure and 
all was fine.
* linking tools/binstall failure.   There is no utimes or futimes on 
interix.  (Its been officially deprecated by Microsoft for utime()) 
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnucmg/html/UCMGch08.asp

Has anybody tried this lately or has this already been determined to be a 
lost cause?

//Jesse Off