From mboxrd@z Thu Jan 1 00:00:00 1970 From: Colin Ngam Date: Thu, 15 May 2003 15:05:28 +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 David Mosberger wrote: > >>>>> On Thu, 15 May 2003 08:17:58 -0500, Colin Ngam said: > > Colin> Anyway, to make a long story short, we like to "extend" these > Colin> interfaces to return DMA addresses of 64 bits if and when the > Colin> driver has the full capabality to support DAC - via it's DMA > Colin> mask capability setting. > > Colin> This extention will not break current usages of these > Colin> interface, and as driver changes, this extension will enable > Colin> platforms to support all of it's Physical Memory via the > Colin> above 2 Interfaces without exhausting limited system mapping > Colin> resources. > > James and I have been discussing this very point for the last week or > so. My preferred solution is to add an explicit dma-mask argument to > coherent/non-coherent allocators, but James prefers to do this via a > new GFP flag (GFP_DMA32 or some such). Hi David, I actually like the flag as a parameter because it allows platform specific extensions to pass in platform specific capabilities that can be ignored by platform that does not support these capabilities. I do not know whether using the same set of flags i.e.GFP_XXX would overload it's meanings to other MM routines but I really like the a flag parameter, that will provide capability for Platform specific hints. Thanks. Colin > > > --david