Just tried the netwinder configuration and got the following error during 
"make depend":

/usr/src/sys/arch/netwinder/conf$ /usr/bin/config GENERIC
/usr/src/sys/arch/netwinder/conf$ cd ../compile/GENERIC
/usr/src/sys/arch/netwinder/compile/GENERIC$ make depend
...

sh ../../../../kern/genassym.sh cc  -O2 -march=armv4 -mtune=strongarm 
-Werror -Wall -Wcomment -Wpointer-arith -Wno-uninitialized -Wno-main -I. 
-I../../../../arch -I../../../.. -nostdinc -DDIAGNOSTIC -DMAXUSERS=32 
-D_KERNEL -D_KERNEL_OPT -Dnetwinder   < ../../../../arch/arm32/arm32/genass
ym.cf > assym.h.tmp &&  mv -f assym.h.tmp assym.h
cc1: warnings being treated as errors
../../../../uvm/uvm_map.h: In function `vmi_list_lock':
In file included from ../../../../uvm/uvm_extern.h:449,
                 from /tmp/23995.c:12:
../../../../uvm/uvm_map.h:264: warning: implicit declaration of function 
`splhigh'
../../../../uvm/uvm_map.h: In function `vmi_list_unlock':
../../../../uvm/uvm_map.h:275: warning: implicit declaration of function 
`splx'
*** Error code 1