DMA

[David Steffens]

In article <8186 at brazos.Rice.edu>, Sun-Spots Volume 9, Issue 180, message 13
kevin at corp.sun.com (Kevin Sheehan {Consulting Poster Child}) writes:
> On the SS1, all of the kernel context is visible to the SBus devices,
> so all you really need to do is use bp_mapin() to make it visible,
> then set up the xfer.

In article <8228 at brazos.Rice.edu>, Sun-Spots Volume 9, Issue 185, message 1
jeffz at sun.com (Jeffrey Zank - SBus Software) writes:
> If you are using DVMA, 600 KBytes sounds about right
> for mb_mapalloc() and mb_mapfree() type of usage.  ...
> If you're not using DVMA you might try bp_mapin() and bp_mapfree()
> and set your own size in minphys().  ...
> All the above discussion is under SunOS 4.1
> on the 4/60 and 4/65 class machines.

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?

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?

{harvard,mit-eddie,think}!eplunix!das	David Allan Steffens
243 Charles St., Boston, MA 02114	Eaton-Peabody Laboratory
(617) 573-3748 (1400-1900h EST)		Mass. Eye & Ear Infirmary