Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965100AbWH2Qll (ORCPT ); Tue, 29 Aug 2006 12:41:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965103AbWH2Qlk (ORCPT ); Tue, 29 Aug 2006 12:41:40 -0400 Received: from mailer.gwdg.de ([134.76.10.26]:35229 "EHLO mailer.gwdg.de") by vger.kernel.org with ESMTP id S965100AbWH2Qlj (ORCPT ); Tue, 29 Aug 2006 12:41:39 -0400 Date: Tue, 29 Aug 2006 18:30:19 +0200 (MEST) From: Jan Engelhardt To: Arjan van de Ven cc: Dong Feng , Andi Kleen , Nick Piggin , Paul Mackerras , Christoph Lameter , David Howells , linux-kernel@vger.kernel.org Subject: Re: The 3G (or nG) Kernel Memory Space Offset In-Reply-To: <1156867503.2722.72.camel@laptopd505.fenrus.org> Message-ID: References: <1156867503.2722.72.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Report: Content analysis: 0.0 points, 6.0 required _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 927 Lines: 23 >> >> Sorry for my typo. I actually means "0-1G physical memory space." My >> question is actually why there is a 3G offset from linear kernel to >> physical kernel. Why not simply have kernel memory linear space >> located on 0-1G linear address, and therefore the physical kernel and >> linear kernel just coincide? > >the price for that would be that you would have to flush all the tlb's >on each syscall. That's seen as a quite hefty price by many kernel >developers. Since it's all just virtual addresses, is the TLB flush really that much different when kernelspace runs from (virtual) 0x00000000-0x3FFFFFFF rather than (virtual)0xC000000-0xFFFFFFFF? Jan Engelhardt -- - 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/