Subject: Re: DMA beyond end of isa
To: None <mike.long@analog.com>
From: mark thompson <thompson@owl.csusm.edu>
List: port-i386
Date: 12/27/1995 20:37:30
   Date: Wed, 27 Dec 95 15:31:15 EST
   From: Mike Long <mike.long@analog.com>

   >Date: Tue, 26 Dec 1995 00:25:22 -0500
   >From: David Mazieres <dm@amsterdam.lcs.mit.edu>

   >Alternatively, where are the bounce buffers implemented in OpenBSD?  I
   >downloaded the actual aha1542 driver but it was identical to the
   >NetBSD one.  Is there some piece of code from OpenBSD that I can drop
   >into the NetBSD kernel?  (I don't care how inelegant it is--I need to
   >stop swapping!)

   The OpenBSD bounce-buffer code probably lives somewhere in
   /sys/dev/isa/isadma.* ; see if you can find it there.

I downloaded OpenBSD over the last couple of days and diffed the whole
tree with 1.1. They have *no* differences that I can attribute to bounce
buffers. In fact, there are *darn* few differences, except for the
kernel being renamed from netbsd to bsd. Makes me wonder just what the
big deal is supposed to be!

Maybe I just caught them at a bad time?

-mark

p.s. From OpenBSD's aha1542.c:
                                        /* check it fits on the ISA bus */
                                        if (thisphys > 0xFFFFFF) {
                                                printf("%s: DMA beyond"
                                                        " end of ISA\n",
                                                        aha->sc_dev.dv_xname);
                                                xs->error = XS_DRIVER_STUFFUP;
                                                aha_free_ccb(aha, ccb, flags);
                                                return COMPLETE;
                                        }