>From: Brian Chase <brianc@carpediem.com>
>
>I noticed that sys/arch/vax/vsa/ncr.c has a commented out define at the
>top of the source file for "#define POLL_MODE".  Is this some sort of
>clean way to create a driver for the VS3100's with PIO only SCSI
>functionality, or do we still need to trick it by raising the minimum DMA
>access size?

POLL_MODE existed long before I discovered the PIO hack.  POLL_MODE
uses DMA to do the transfer, but polls the device for completion
instead of using an interrupt handler.  This doesn't seem to help with
the DMA problems at all.  You need the PIO hack, to completely avoid
DMA tranfers.

Cheers,
entropy

--
entropy -- it's not just a good idea, it's the second law.