DVA/DVMA

[Jeffrey Zank - SBus Software]

| What are the implications, if any, of these comments for a DMA driver
| running on a Sun4/260 under SunOS4.1?  Is there now a general way around
| the 600K DVMA limit, i.e. does bp_mapin() on the 4/260 work as described
| for the SS1?

If you are using DVMA any Sun architechure you will be limited to transfer
sizes less than the total DVMA resoruce map size (1MB on non the 4/260 me
thinks).  If you use bp_mapin() you should be able to get your minphys
size for transfers, which could be greater than 1MB.  bp_mapin() does not
use the DVMA map array.

| And while I've got your attention...  I'm currently using mbsetup(),
| MBI_ADDR() and mbrelse() as described in the 24 Apr 89 edition of "Writing
| Device Drivers".  I have skimmed the 27 Mar 90 edition of "Writing Device
| Drivers" and the "SunOS4.1 Release Manual", but have been unable to find a
| definitive answer to the following question: Are there any changes I
| absolutely _must_ make to a DMA driver which runs under SunOS4.0.3 in
| order to run it under SunOS4.1?

None that I know of.