From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Grundler Date: Thu, 15 May 2003 19:16:37 +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 On Thu, May 15, 2003 at 08:17:58AM -0500, Colin Ngam wrote: > Hi, > > The Altix PCI-X Bridge chipset expects devices that runs in > PCI-X mode to always be 64Bit DMA Address capable(DAC). This > requirement is directly in conflict with both the > pci_alloc_consistent() and dma_alloc_coherent() interfaces. I don't (yet) see the conflict. Can't the 32-bit address can be extended to 64-bits as described in the dma_alloc_coherent() interface? Are you running out of 32-bit memory? > 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. jbarnes@sgi.com proposed this before. On April 23, 2002, davem wrote: | %99 of PCI chips out there do not support DAC addressing for things | like descriptor tables etc. So it's not a matter of "well" it's | a matter of "at all". If you want the complete thread, check ia64-linux 2002 mail archives. hth, grant