Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758805AbXEMGto (ORCPT ); Sun, 13 May 2007 02:49:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756978AbXEMGth (ORCPT ); Sun, 13 May 2007 02:49:37 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:36865 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755109AbXEMGth (ORCPT ); Sun, 13 May 2007 02:49:37 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: "Yinghai Lu" Cc: "Andi Kleen" , "Andrew Morton" , "Vivek Goyal" , "Linux Kernel Mailing List" Subject: Re: [PATCH]x86_64: build and use GDT on copied compressed kernel References: <86802c440705122233y327756e7te534199f46b2059d@mail.gmail.com> <86802c440705122329y27c6ef92v8cff43d52b99ae69@mail.gmail.com> Date: Sun, 13 May 2007 00:48:53 -0600 In-Reply-To: <86802c440705122329y27c6ef92v8cff43d52b99ae69@mail.gmail.com> (Yinghai Lu's message of "Sat, 12 May 2007 23:29:23 -0700") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1114 Lines: 26 "Yinghai Lu" writes: > On 5/12/07, Eric W. Biederman wrote: >> Overwriting the GDT should be fine because we don't reload the segments, >> after we overwrite it. GDT entries are only read when we load segments. >> Interrupts are disabled so that should not cause a problem. >> >> Why do you think the current behaviour is a problem? > > just think if GDT should not be overwriten when we are still under > that GDT setting. > didn't have chance to test that in HDT or other debug device, when > setting breaking point after that GDT is overwriten. It would be interesting to see if you could produce a failure using that gdt, I don't think you will be able to, even with a debugger. For data segments we never use that GDT, it is only for the code segment we use the GDT and that only to get us into 64bit mode. Eric - 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/