From owner-freebsd-hackers Thu Oct 28 20:41:58 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from server.baldwin.cx (jobaldwi.campus.vt.edu [198.82.67.146]) by hub.freebsd.org (Postfix) with ESMTP id 0DF0115512 for ; Thu, 28 Oct 1999 20:41:46 -0700 (PDT) (envelope-from jobaldwi@vt.edu) Received: from john.baldwin.cx (john [10.0.0.2]) by server.baldwin.cx (8.9.3/8.9.3) with ESMTP id XAA00750; Thu, 28 Oct 1999 23:41:28 -0400 (EDT) (envelope-from jobaldwi@vt.edu) Message-Id: <199910290341.XAA00750@server.baldwin.cx> X-Mailer: XFMail 1.3.1 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: Date: Thu, 28 Oct 1999 23:41:28 -0400 (EDT) From: John Baldwin To: Chuck Youse Subject: Re: Limitations in FreeBSD Cc: hackers@FreeBSD.ORG, Julian Elischer , Matthew Dillon , Michael Beckmann , Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 29-Oct-99 Chuck Youse wrote: > >> > That´s why I´m looking for a way of having large mmap´able >> > files. Are you saying that ALL Intel CPUs, including PIII, can >> > only >> > address 4 GB? >> >> That's correct; it's why the ia32 architecture has a '32' in its >> name. > > I don't believe that's true. I don't have any hard evidence within > easy > reach, but with the introduction of the Pentium, the address space > was > increased. A user process, of course, can only have 4G of > addressible > space (32-bit addresses) but the OS can map pages of the 4G space > into a > larger area. It was the PPro, not the Pentium, and it is called Page Address Extensions.. it does some funky stuff with the page tables to gain an extra 4 bits for a total of 64 gig of addressable space. It ends up using 4k and 2mb pages. > Something to do with 4MB pages instead of 4K pages. This is a seperate issue known as Page Size Extensions and actually was present in some i486dx4/100's. Basically, it allows you to directly map 4mb with a single page entry by leaving out the bottommost layer of the page tables. > Again, I could be wrong on this one. > > Chuck Youse --- John Baldwin -- http://www.cslab.vt.edu/~jobaldwi/ PGP Key: http://www.cslab.vt.edu/~jobaldwi/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message