sundar@wheaties.ai.mit.edu (Sundar Narasimhan) (12/22/88)
Hi: We have a 25 MHz Sun 3-280 with a high-res monitor hooked upto another VME through an HVE-2000 bus-to-bus adaptor. Our 16MHz earlier suns (3-160's) have no problems under such a configuration. With the faster boards though, any vmebus activity on the slave vme causes the sun to freeze up for a while after which it emits one of these messages zs0: silo overflow Sometimes instead of zs0, other minor devices will be indicated (zs1 or zs2 or zs3). We have determined that no interrupt activity is actually present across the bus adaptor, that it is not window system programs like suntools or X that cause this problem, and that the serial line, mouse or keyboard have nothing to do with this. We have also determined that we have the right rev no./level of the 280 boards which reputedly had a lot of VME bus problems initially. One obvious hypothesis is that somehow the address mapping is all confused and that the zs interfaces are responding to activity on the vme bus when they shouldn't because they are supposed to be local (on-board the sun cpu). Has anyone else seen this problem, and/or can someone explain how the address mapping works to distinguish local from vme bus accesses? We have tried the Sun customer support route and there wasn't anyone in Sun who we talked to that could give us a clearer idea of what could be happening.. -Sundar