[Linux-ia64] Re: 64 Bits DMA Addresses for Alloc Consistent Interfaces.

David S. Miller
2003-05-15T20:07:39Z

From: Colin Ngam <cngam@sgi.com>
Date: Thu, 15 May 2003 08:17:58 -0500

Anyway, to make a long story short, we like to "extend" these
interfaces to return DMA addresses of 64 bits if and when the
driver has the full capabality to support DAC - via it's
DMA mask capability setting.

All devices I am aware of do not support 64-bit addresses for their
descriptors, only 32-bit.

There is a huge difference between using a "64-bit address" and
requiring to generate a DAC cycle, the latter of which is
probably what you need and that is independant of what kind of
address pci_alloc_consistent() is giving you.