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

David S. Miller
2003-05-16T00:17:20Z

From: Colin Ngam <cngam@sgi.com>
Date: Thu, 15 May 2003 18:57:09 -0500

It is in the PCI-X Spec that all PCI-X devices in PCI-X Mode have
to support DAC.

Having to support DAC cycles does not mean that it must support full
64-bit DMA addresses in it's descriptors.

A cost sensitive PCI-X device may wish to use 32-bit addressing in
it's descriptors in order to keep pin counts down etc.