From owner-cvs-src@FreeBSD.ORG Wed Apr 26 16:15:11 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 778C816A408; Wed, 26 Apr 2006 16:15:11 +0000 (UTC) (envelope-from imp@bsdimp.com) Received: from harmony.bsdimp.com (vc4-2-0-87.dsl.netrack.net [199.45.160.85]) by mx1.FreeBSD.org (Postfix) with ESMTP id C981243D48; Wed, 26 Apr 2006 16:15:09 +0000 (GMT) (envelope-from imp@bsdimp.com) Received: from localhost (localhost.village.org [127.0.0.1] (may be forged)) by harmony.bsdimp.com (8.13.4/8.13.4) with ESMTP id k3QGCVD8038563; Wed, 26 Apr 2006 10:12:32 -0600 (MDT) (envelope-from imp@bsdimp.com) Date: Wed, 26 Apr 2006 10:12:45 -0600 (MDT) Message-Id: <20060426.101245.90994186.imp@bsdimp.com> To: scottl@samsco.org From: "M. Warner Losh" In-Reply-To: <444F0923.8050508@samsco.org> References: <20060426103623.M1847@epsplex.bde.org> <20060425223519.F65802@ns1.feral.com> <444F0923.8050508@samsco.org> X-Mailer: Mew version 3.3 on Emacs 21.3 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: src-committers@FreeBSD.org, bde@zeta.org.au, jhb@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org, mj@feral.com 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 16:15:11 -0000 In message: <444F0923.8050508@samsco.org> Scott Long writes: : 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. bus_size_t is for differences between two bus_addr_t quantities, since it specifies the size of resources on a bus. It is also used for transfer sizes and the like. That's why I think it should be a 64-bit quantity: 64-bit - 64-bit = 64-bit. Warner