From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754757Ab2LNAjK (ORCPT ); Thu, 13 Dec 2012 19:39:10 -0500 Received: from terminus.zytor.com ([198.137.202.10]:41268 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028Ab2LNAjI (ORCPT ); Thu, 13 Dec 2012 19:39:08 -0500 Message-ID: <50CA7515.9080701@zytor.com> Date: Thu, 13 Dec 2012 16:38:45 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Yinghai Lu CC: Thomas Gleixner , Ingo Molnar , "Eric W. Biederman" , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 19/27] x86, boot: update comments about entries for 64bit image References: <1355436141-8668-1-git-send-email-yinghai@kernel.org> <1355436141-8668-20-git-send-email-yinghai@kernel.org> <50CA6478.20008@zytor.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/2012 04:13 PM, Yinghai Lu wrote: > On Thu, Dec 13, 2012 at 3:27 PM, H. Peter Anvin wrote: >> On 12/13/2012 02:02 PM, Yinghai Lu wrote: >>> + * If we come here from a bootloader, kernel(text+data+bss+brk), >>> + * ramdisk, zero_page, command line could be above 4G. >>> + * We depend on an identity mapped page table being provided >>> + * that maps our entire kernel(text+data+bss+brk), and hopefully >>> + * all of memory. >> >> We should make it explicit what we depend on. We certainly *can* depend >> only on text+data+bss+brk ... with the dynamic page table approach we >> can do that, and that would be most conservative; if we depend on other >> things we should make that explicit, not just here but in boot.txt. > > yes, in my version, only need kernel(text+data+bss+brk) get mapped. > aka the INIT_SIZE for decompressing. > It is definitely the minmum we can rely on, and so is the minimum we should rely on. In fact, we don't even need .bss/.brk to be mapped, but we probably should require that as a matter of protocol. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.