From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265261AbUE0VSh (ORCPT ); Thu, 27 May 2004 17:18:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265274AbUE0VSh (ORCPT ); Thu, 27 May 2004 17:18:37 -0400 Received: from 209-128-98-078.BAYAREA.NET ([209.128.98.78]:25752 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S265261AbUE0VSf (ORCPT ); Thu, 27 May 2004 17:18:35 -0400 Message-ID: <40B65B0F.9090106@zytor.com> Date: Thu, 27 May 2004 14:18:07 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.6) Gecko/20040510 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Dave Jones CC: Linux Kernel Subject: Re: mem= handling mess. References: <20040527200320.GR22630@redhat.com> In-Reply-To: <20040527200320.GR22630@redhat.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Dave Jones wrote: > At some point in time during 2.4, parse_cmdline_early() changed > so that it handled such boot command lines as.. > > mem=exactmap mem=640k@0 mem=511m@1m > > And all was good. This change propagated forward into 2.5, > where it sat for a while, until hpa freaked out and > Randy Dunlap sent in cset 1.889.364.25 > > ChangeSet 1.889.364.25 2003/03/16 23:22:16 akpm@digeo.com > [PATCH] Fix mem= options > > Patch from "Randy.Dunlap" > > Reverts the recent alteration of the format of the `mem=' option. This is > because `mem=' is interpreted by bootloaders and may not be freely changed. > > Instead, the new functionality to set specific memory region usages is > provided via the new "memmap=" option. > > The documentation for memmap= is added, and the documentation for mem= is > updated. > > This is all well and good, but 2.4 never got the same treatment. > Result ? Now users are upgrading their 2.4 systems to 2.6, > and finding that they don't boot any more. > (See https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=124312 > for example). > > The "`mem=' is interpreted by bootloaders and may not be freely changed." > obviously hasn't broken the however many users of this we have in 2.4 > so I don't buy that it'll break in 2.6 either. As its now in 2.4 > (and has been there for some time), this is something that bootloaders > will just have to live with. > It was changed to memmap= I thought. The command line suggested above, for example, WILL NOT boot with any correctly operating boot loader. Unfortunately, given its history I suspect GRUB is nowhere in that category. I think telling people to use memmap= instead of mem= is the only sane way to deal with this. What is even more puzzling is that the command line used by the user in that question is bogus, and should be *exactly* identical to "mem=512M", but the bug report indicates that doesn't work on that machine. Thus, there is something more seriously wrong. -hpa