From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Grundler Subject: Re: [parisc-linux] PATCH/RFC: discontig mem support for hppa Date: Sat, 3 Jul 2004 12:37:12 -0600 Message-ID: <20040703183712.GA10458@colo.lackof.org> References: <20040703180852.GD18628@tausq.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: parisc-linux@lists.parisc-linux.org To: Randolph Chung Return-Path: In-Reply-To: <20040703180852.GD18628@tausq.org> List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: parisc-linux-bounces@lists.parisc-linux.org On Sat, Jul 03, 2004 at 11:08:52AM -0700, Randolph Chung wrote: > I am not clear about whether we need to treat "low memory" > differently from "high memory" in any cases. willy pointed out to me > that since we have a IOMMU we don't really need to care about ZONE_DMA > vs ZONE_NORMAL, That's correct. Becuase the virtual coherence index needed for cache coherency, 32-bit PCI devices will always go through the IOMMU even to DMA to physical memory < 4GB. My hope is with ZX1 IOMMU, 64-bit devices can provide the virtual coherence index as part of the DMA address. I haven't done all the research yet to verify this will actually work. grant _______________________________________________ parisc-linux mailing list parisc-linux@lists.parisc-linux.org http://lists.parisc-linux.org/mailman/listinfo/parisc-linux