From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Miller" Date: Thu, 15 May 2003 20:07:39 +0000 Subject: [Linux-ia64] Re: 64 Bits DMA Addresses for Alloc Consistent Interfaces. Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org From: Colin Ngam 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.