Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262591AbTIQCJk (ORCPT ); Tue, 16 Sep 2003 22:09:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262593AbTIQCJk (ORCPT ); Tue, 16 Sep 2003 22:09:40 -0400 Received: from holomorphy.com ([66.224.33.161]:36817 "EHLO holomorphy") by vger.kernel.org with ESMTP id S262591AbTIQCJh (ORCPT ); Tue, 16 Sep 2003 22:09:37 -0400 Date: Tue, 16 Sep 2003 19:10:45 -0700 From: William Lee Irwin III To: Ben Johnson Cc: "Martin J. Bligh" , Linux Kernel Mailing List Subject: Re: linear vs. logical addresses? how does cpu interpret kernel addrs? Message-ID: <20030917021045.GY4306@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Ben Johnson , "Martin J. Bligh" , Linux Kernel Mailing List References: <20030916154747.A22526@blarg.net> <1562370000.1063759683@[10.10.2.4]> <20030917005446.GW4306@holomorphy.com> <1563260000.1063760286@[10.10.2.4]> <20030916184421.A25733@blarg.net> <20030917015527.GX4306@holomorphy.com> <20030916190723.A26053@blarg.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030916190723.A26053@blarg.net> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1220 Lines: 27 On Tue, Sep 16, 2003 at 06:55:27PM -0700, William Lee Irwin III wrote: >> You might want to look at intel's volume 3. They're kept in dedicated >> registers separate from the pointers and used implicitly. On Tue, Sep 16, 2003 at 07:07:23PM -0700, Ben Johnson wrote: > I've been reading that too. The problem is that there are 6 segment > selector registers and 4 of those are just for data segments. several > data segments can be in use simultaneously and they can all have > different base addresses and limits. The only explanation I've found so > far about how a segment is chosen is that logical address are 48-bit > values, yet sizeof(void *) == 4. there has to be a way to match up > pointer with a segment, but I am unable to find it so far. (maybe I > need a nap.) Logical addresses aren't 48-bit; they're just offset from linear (and vice-versa). The way the extra data segment registers are used is by explicitly qualifying operands with segments. -- wli - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/