K 10
svn:author
V 2
se
K 8
svn:date
V 27
2009-10-31T17:06:36.586639Z
K 7
svn:log
V 870
While certain supported Symbios/LSI SCSI chips (532c896, 53c1000, 53c1010)
do support 64bit addresses, the current SCRIPTS code supports only 32bit
addresses causing data corruption for buffer addresses >4GB. This problem
affects 64bit machines with more than 4GB RAM or amd64 with 4GB and
memory hole remapping.
Work-around this problem with a bus_dma tag that requests bounce-buffers
for addresses >4GB. This causes some overhead, but given the maximum SCSI
bus speed of 160MB/s compared, the effect should hardly be noticeable.
The problem was reported by Mike Watters (mike at mwatters net) who also
verified that this fix cures the problem.

Since this change is a NOOP on systems with less than 4GB RAM and fixes
data corruption (in RAM and on disk) on systems with more than 4GB, I hope
that this change is accepted for 8.0.

MFC after:	3 days (pending approval)

END