From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751541AbWFVWBA (ORCPT ); Thu, 22 Jun 2006 18:01:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751550AbWFVWBA (ORCPT ); Thu, 22 Jun 2006 18:01:00 -0400 Received: from dspnet.fr.eu.org ([213.186.44.138]:12303 "EHLO dspnet.fr.eu.org") by vger.kernel.org with ESMTP id S1751541AbWFVWBA (ORCPT ); Thu, 22 Jun 2006 18:01:00 -0400 Date: Fri, 23 Jun 2006 00:00:57 +0200 From: Olivier Galibert To: linux-kernel@vger.kernel.org Subject: Re: Is the x86-64 kernel size limit real? Message-ID: <20060622220057.GB52945@dspnet.fr.eu.org> Mail-Followup-To: Olivier Galibert , linux-kernel@vger.kernel.org References: <20060622204627.GA47994@dspnet.fr.eu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 22, 2006 at 02:38:02PM -0700, H. Peter Anvin wrote: > It turns out x86-64, unlike i386, does still have a hardcoded limit, > but the limit in build.c is wrong: > > kernel/head.S: > /* 40MB kernel mapping. The kernel code cannot be bigger than that. > When you change this change KERNEL_TEXT_SIZE in page.h too. */ > /* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */ > > So this should be replaced by KERNEL_TEXT_SIZE in page.h, or better, > this should be done dynamically in x86-64 too. Interesting. KERNEL_TEXT_SIZE wouldn't work though, since that's the decompressed size while the 4Mb limit is on the compressed size. As a datapoint, though, the uncompressed image is 15.7Mb, for a 4.5Mb compressed image. OG.