HP OpenVMS Systems

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QBUS driver problems

The Question is:

  Dear Mr. Wizard:

  Its OK, you don't have to read my crash dump.  I tool that step
  myself.

  Are there any known bugs in VMS 6.1 which would cause LOADALT to
  screw up a Qbus system?

  Alternatively, does anyone know any details we can check to verify
  whether we're using it properly?

Details:

  VAX 4000-500A
  VMS 6.1

  Device driver does a LOADALT, within a few instructions of returning from
  IOC$LOADALTMAP the system crashes due to a machine check:  asynchronous
  memory write error.  Sometimes the system cannot access the system disk
  to reboot until we do a few extra console init commands, so we think the
  Qbus is getting messed up somehow.

  Worked OK under VMS 5 (5.5-2HW, I think).

The Answer is:

   It's quite possible to encounter memory corruptions working with
   LOADALT -- I encountered similar errors when I had incorrectly
   initialized the scatter-gather map.  It's also possible that the
   Q-bus board is getting wedged in an odd state.