Traditionally, kernels have been buildable in isolation: if you clone
/sys and have a suitable config, you can build a kernel anywhere.

This seems to no longer be true of NetBSD.  On a 2.0 machine, I copied
/sys to ~/sys (I'm doing some hackery that I don't want to plow back
into /sys until I have it working), and ran config without errors, but
when I tried to make depend in the resulting build directory, I got

...
#    create  GENERIC/param.c
rm -f param.c
cp ../../../../conf/param.c .
make: don't know how to make ../../../../../contrib/sys/dev/ic/athhal_osdep.c. Stop

That looks as though it's trying to reach over from /usr/src/sys into
/usr/src/contrib/sys.

Is it simply no longer supported by NetBSD to build kernels without the
full /usr/src context?  Or is this a bug worth sending-pr?  Or what?

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