On a sparcstation20 w/ dual hypersparc 150s and 512M RAM,
trying to compile a new kernel with ./build.sh,
I ran into sbrk problems breaking the compile.
This occurred at different places on subsequent attempts.

I googled around and saw references to the need to
up NKMEMPAGES and/or NKMEMPAGES_MAX_DEFAULT
in the kernel configuration file, but there's no default
settings in GENERIC (2.1) so was skittish about trying to
manipulate it there.

I saw references to changing vm.nkmempages w/ sysctl
but that does not work, either by setting the sysctl.conf
in etc. & reboot or by trying to write the value directly
(I saw that it is rigged non-writable, but several emails floating
around the web referred to using sysctl to do this so I
tried anyway)

I also saw a reference to changing this value in param.h
in the source tree.  I did not attempt this.

Could someone explain how this should be set on netbsd
sparc 2.1 (or 3.0, I'll probably upgrade when it is released).

BTW, I rebooted with the new nkmempages setting in
/etc/sysctl.conf and though that didn't do anything in
that the nkmempages value stayed the same low value,
I successfully ran a kernel compile then with only a
single ssh session on the box.  I don't know if the reboot
fixed some memory leak or if the 2 extra ssh sessions, one
of which was running 'top', made a difference. 
I was running top to monitor memory/swap/cpu usage
during the compile .... there was no obvious memory
loss during the compile, but then I didn't have my eyes
on 'top' output right before the compile crashed (stopped
with the sbrk memory failure).

Thanks,
Heitzso