[comp.periphs.scsi] Virtual 8086 mode and bus-mastering controllers

iverson@xstor.UUCP (Tim Iverson) (09/29/90)

I'm curious about the effects of using a virtual 8086 mode program (e.g.
soft-ice, qemm386, 386max, windows 386, dos extenders, etc.) with 1st party
DMA host adapters like the Adaptec 154x series.  Since the adaptec h/a
requires physical addresses to transfer data, it seems like there might be
a serious problem here if v8086 VMMs don't ensure that virtual addresses
correspond to physical.

Does anyone know more about how v8086 mode works and if any of the VMMs
take special pains to handle this situation?  I do know that soft-ice, for
one, will work with the 1542, but I don't know if this is by chance or
design or if there are any special considerations that I should be aware of.

If you have any knowledge that can shed some light on this issue, I'd love
to hear from you.  (E-mail replies will be summarized).

Thanks!

- Tim Iverson
  uunet!xstor!iverson