Strange behavior w/256MB RAM on Lemote YeeLoong

The question of how much memory my Lemote YeeLoong had:

  http://mail-index.netbsd.org/port-evbmips/2016/12/06/msg000342.html

was speculating whether a problem seen on ERLITE (which has split physical
memory with 2nd 256MB located above 4GB) might be in play here as well.

My YeeLoong came with 1GB installed.  As I discovered recently, it's an
ordinary DDR2-800 (PC2-6400) SO-DIMM, so it can be changed.  I had been
interested in seeing if more memory were possible, but the above-mentioned
problem meant that observing behavior with less memory would potentially
be useful.

I managed to scrounge up 512MB (PC2-5300) and 256MB (PC2-3200) DDR2
SO-DIMMs.  PMON's 'mt' memory test completes successfully.  Linux operates
normally with the 256MB and 512MB parts.

With the 512MB part, NetBSD works normally.  The machine hangs hard when
accessing umass(4) devices, but this is no different than with the original
1GB part.

Booting NetBSD with the 256MB part installed, the machine boots, but
then behaves strangely.  It claims one or more MBR partitions on the
internal SATA disk (wd0) exceed the size of the disk.  It can configure
the network interface both statically and via DHCP but subsequent network
communication fails in one way or another.  NFS root times out, NFS
mount from local-disk boot fails with either portmapper unable to send
or time-out.  Name resolution fails.  'ping'ing a known local host loses
some packets and receives duplicate replies to others.

Perhaps this points to some other problem?  Is anyone else in a position
to test LESS memory on a Lemote system?

-- 
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