From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with archive (Exim 4.43) id 1KbKOF-0007VL-5X for mharc-grub-devel@gnu.org; Thu, 04 Sep 2008 15:21:11 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KbKOC-0007UG-Kz for grub-devel@gnu.org; Thu, 04 Sep 2008 15:21:08 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KbKOB-0007TR-5b for grub-devel@gnu.org; Thu, 04 Sep 2008 15:21:08 -0400 Received: from [199.232.76.173] (port=45192 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KbKOA-0007TN-VA for grub-devel@gnu.org; Thu, 04 Sep 2008 15:21:06 -0400 Received: from aybabtu.com ([69.60.117.155]:53048) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1KbKOA-0001aB-Cm for grub-devel@gnu.org; Thu, 04 Sep 2008 15:21:06 -0400 Received: from [192.168.10.10] (helo=thorin) by aybabtu.com with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.69) (envelope-from ) id 1KbKDl-00087U-Sf for grub-devel@gnu.org; Thu, 04 Sep 2008 21:10:22 +0200 Received: from rmh by thorin with local (Exim 4.63) (envelope-from ) id 1KbKMe-0002Oj-95 for grub-devel@gnu.org; Thu, 04 Sep 2008 21:19:32 +0200 Date: Thu, 4 Sep 2008 21:19:32 +0200 From: Robert Millan To: The development of GRUB 2 Message-ID: <20080904191932.GA9133@thorin> References: <20080830124058.GI16775@thorin> <48BE6ACD.7090607@symantec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48BE6ACD.7090607@symantec.com> Organization: free as in freedom X-Message-Flag: Worried about Outlook viruses? Switch to Thunderbird! www.mozilla.com/thunderbird X-Debbugs-No-Ack: true User-Agent: Mutt/1.5.13 (2006-08-11) X-detected-kernel: by monty-python.gnu.org: Genre and OS details not recognized. Subject: Re: Idea: Move kernel to upper memory X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: The development of GRUB 2 List-Id: The development of GRUB 2 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Sep 2008 19:21:09 -0000 On Wed, Sep 03, 2008 at 04:15:33PM +0530, BVK Chaitanya wrote: > Hi, > > > What is the conclusion of this thread? is this idea still explored? > > > Robert Millan wrote: > > > >The first concern that comes to mind is how would GRUB coexist with the > >payload area which precisely starts at 0x100000. But I expect we'd face > >many unexpected issues. > > > > Does this mean, GRUB needs to fit within 1MB limit when all its modules > are loaded? More clearly, are there any limits on where (and how many) > grub modules can be dynamically loaded currently? > > Since payload(s) needs to be present at their precise positions only > after the boot command, we can always deterministically /schedule/ > memmove operation to be executed as part of boot command. > > Since boot command is the last command executed by GRUB (correct me if > not), we can overwrite any GRUB code/data at that point. This also > needs boot command to exist in low memory. This is already done. See grub_multiboot_{forward,backward}_relocator variables and how they're used in the multiboot loader. -- Robert Millan The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and how) you may access your data; but nobody's threatening your freedom: we still allow you to remove your data and not access it at all."