From owner-freebsd-hackers Thu Aug 2 21:59:48 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from avocet.mail.pas.earthlink.net (avocet.mail.pas.earthlink.net [207.217.121.50]) by hub.freebsd.org (Postfix) with ESMTP id 6662A37B405 for ; Thu, 2 Aug 2001 21:59:45 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from mindspring.com (dialup-209.244.104.136.Dial1.SanJose1.Level3.net [209.244.104.136]) by avocet.mail.pas.earthlink.net (EL-8_9_3_3/8.9.3) with ESMTP id VAA18167; Thu, 2 Aug 2001 21:58:44 -0700 (PDT) Message-ID: <3B6A2FAC.28F2F959@mindspring.com> Date: Thu, 02 Aug 2001 21:59:24 -0700 From: Terry Lambert Reply-To: tlambert2@mindspring.com X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Rik van Riel Cc: mark tinguely , culverk@wam.umd.edu, craiglei@pasia.com.cn, freebsd-hackers@FreeBSD.ORG Subject: Re: How to visit physical memory above 4G? References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Rik van Riel wrote: > > The addressing use 64 bits for a memory pointer and the additional > > page indirection add to the overhead. The stickler is the MMU is > > still 32 bits. This means the PAE must segment the 64GB space into > > 4GB segments or 4 1GB segments. The OS must manage which pages are > > viewable to the process at this time. > > There's a better option. The application does this stuff > itself, by mapping and unmapping SHM segments. Not surprisingly, this doesn't work if your application is the kernel, and the data is mbufs, open file structures, sockets, tcpcb's, or inpcb's. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message