From owner-cvs-src@FreeBSD.ORG Wed Apr 26 05:46:57 2006 Return-Path: X-Original-To: cvs-src@FreeBSD.org Delivered-To: cvs-src@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 466DC16A508; Wed, 26 Apr 2006 05:46:57 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4FA2143D5A; Wed, 26 Apr 2006 05:46:50 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.254.11] (junior.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id k3Q5kBhD087875; Tue, 25 Apr 2006 23:46:11 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <444F0923.8050508@samsco.org> Date: Tue, 25 Apr 2006 23:46:11 -0600 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.12) Gecko/20051230 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Matthew Jacob References: <444E7750.206@samsco.org> <200604251540.00170.jhb@freebsd.org> <444E7BFE.4040800@samsco.org> <20060425.173236.74726638.imp@bsdimp.com> <444EB6A1.3060901@samsco.org> <20060426103623.M1847@epsplex.bde.org> <20060425223519.F65802@ns1.feral.com> In-Reply-To: <20060425223519.F65802@ns1.feral.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-1.4 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.1.1 X-Spam-Checker-Version: SpamAssassin 3.1.1 (2006-03-10) on pooker.samsco.org Cc: src-committers@FreeBSD.org, jhb@FreeBSD.org, Bruce Evans , cvs-src@FreeBSD.org, cvs-all@FreeBSD.org, Warner Losh Subject: Re: cvs commit: src/sys/dev/bce if_bcereg.h X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Apr 2006 05:46:57 -0000 Matthew Jacob wrote: > >> Supporting sizes >= 4G sounds unreasonable. How can a single device >> need or even address so much space, even on 64-bit arches? For vm, >> virtual memory is sort of a device, but even it is limited to 4G on >> 32-bit arches, and PAE on i386 isn't pessimized by using a larger than >> necessary vm_size_t. > > > I have need to support and help people sell machines that use 32GB of > directly addressable memory. In fact, the EM64T cheat will shortly > become an embarrasment to Intel when people find out that EM64T with PAE > is *not* the same as Opteron (36 vs. 40). > > I'm afraid I don't understand the 'unreasonable' argument here. Linux is > eating your lunch today. Do you want it to eat your dessert as well? > > -matt > bus_size_t is used for things like measuring transfer segment size. There is little chance that Linux, Windows, FreeBSD, or any other OS is ever going to try to DMA more than 2^32 bytes of data in a single bus transaction. Maybe you could contrive a silly infiniband device to do it. Anyways, it has no bearing on whether the CPU, memory controller, or PCI buses can do 64 bit addressing. Scott