From owner-freebsd-questions@FreeBSD.ORG Thu Feb 18 00:52:02 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 34AD61065698 for ; Thu, 18 Feb 2010 00:52:02 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from asmtpout025.mac.com (asmtpout025.mac.com [17.148.16.100]) by mx1.freebsd.org (Postfix) with ESMTP id 1CCEA8FC16 for ; Thu, 18 Feb 2010 00:52:01 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=us-ascii Received: from cswiger1.apple.com ([17.209.4.71]) by asmtp025.mac.com (Sun Java(tm) System Messaging Server 6.3-8.01 (built Dec 16 2008; 32bit)) with ESMTPSA id <0KY000MQFIEOWI50@asmtp025.mac.com> for freebsd-questions@freebsd.org; Wed, 17 Feb 2010 16:52:01 -0800 (PST) X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx engine=5.0.0-0908210000 definitions=main-1002170161 From: Chuck Swiger In-reply-to: <4B7C82F5.7030207@rawbw.com> Date: Wed, 17 Feb 2010 16:52:00 -0800 Message-id: <9D22BE72-E860-44D9-A582-86CE36AB6CBA@mac.com> References: <4B7C493B.1060503@rawbw.com> <20100217150217.393724ed.wmoran@potentialtech.com> <20100217202327.GA23365@owl.midgard.homeip.net> <4B7C82F5.7030207@rawbw.com> To: yuri@rawbw.com X-Mailer: Apple Mail (2.1077) Cc: FreeBSD - Subject: Re: Is it possible to see memory over 3GB on 32-bit FreeBSD? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Feb 2010 00:52:02 -0000 Hi-- On Feb 17, 2010, at 3:59 PM, Yuri wrote: > Erik Trulsson wrote: >> It very much depends on what hardware you have in the system. Just >> about every expansion card or I/O device will reserve some of the >> address space for its own use. Some devices will need a lot of space - a graphics card with 256MB of RAM on it will use (at least) 256MB of the address space for example. > > This doesn't seem like a good idea that video memory is always mapped to system memory. What if one day graphics card gets 4GB RAM? Then we won't even be able to have 32-bit OS working with such card and in 64-bit OS 4GB of memory would be grossly wasted. At one point, there was a considerable advantage to have video card memory fully mapped into untranslated address space so that various things could read or write as they pleased (cf "VESA linear framebuffer"); generally they gained speed advantages from this. With AGP's GART, the amount of memory available for textures, bump-maps, etc, could reside in video card memory, local RAM, or a combination. Modern video cards do not have keep their entire memory space mapped into address space; for example, a nVidia 275 card with 1792 MB of RAM doesn't seem to want more than 256MB of address space under 32-bit Windows platforms. Regards, -- -Chuck