From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesse Barnes Date: Thu, 25 Apr 2002 00:21:19 +0000 Subject: [Linux-ia64] Re: PCI DAC routines for SN 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 Wed, Apr 24, 2002 at 05:08:08PM -0700, David S. Miller wrote: > So if performance isn't an obstacle to implementing a new call, and > I've shown that there are platforms where 64 bit consistent mappings > are better to use than 32 bit mappings when possible, why can't we add > it? Or maybe just a seperate consistent_mask that drivers could set > to indicate they support the operation and let the platform take care > of it? > > Where is the platform where it is a problem to keep around > enough of the _4_ __GIGABYTES__ of consistent memory available > at bootup? > > If you can't keep around enough consistent memory within the > lower 4GB, you have other problems. > > Devices use, EACH, something like a few kilobytes of consistent > memory for descriptors. If you are going to tell me this is > a big deal, you have to be kidding me. > > Why don't you tell me what the real problem is? I thought I did. The issue isn't keeping 4gb around, it's using up the 32 bit mappings in the bridge for 64 bit capable cards. Jesse