On Fri, 20 Apr 2018, Michael Schmitz wrote: > > What's not supported right now is Oktagon SCSI - in contrast to the > above, this card does not have a DMA engine. We have pseudo-DMA support > in the Mac ESP driver, but the Mac uses a 1:1 mapping of physical > addresses into kernel virtual space while the Amiga uses an offset > mapping. The Mac PDMA code would need some modifications for this board > (ideally, just accounting for some offset, nothing major). If someone's > keen to give it a try and wants more details, just let me know.
A PDMA algorithm like the one in g_NCR5380 may be more relevant here (?) On Macs, the PDMA logic circuit is found in a custom Apple ASIC. This suggests that the mac_esp PDMA algorithm may not be very portable. Moreover, this algorithm won't work unless the logic circuits in Oktagon cards raise the appropriate bus faults, as derived from the DMA signalling from the ESP chip. --
