disk controllers w/ 64-bit addressing?

[James Van Artsdalen]

I don't think PIO transfers for s/ATA would be as fast as DMA with
bounce-buffers.  Current ATA disk drives can sustain 60 MB/s in the
fast zones.

I'm wondering if anyone else has done the exercise of looking for a
fast disk system for an AMD64 with more than 4 GB of RAM.  I would
prefer to stay with serail-ATA instead of expensive SCSI but I don't
know if any serial-ATA controllers can directly write to memory above
4 GB without a bounce buffer, or if there is a FreeBSD driver for such
a controller.

Date: Sun, 30 Nov 2003 10:31:40 -0500
From: Dave Feustel <dfeustel at mindspring.com>
Subject: Re: disk controllers w/ 64-bit addressing?

64-bit memory addressing for disk transfers can be done in AMD native mode
via programmed i/o. The question is whether 64-bit memory addressing via
dma-controlled memory transfers is possible and/or supported via the disk driver.