From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH] mmc: boot partition ro lock support Date: Sat, 22 Oct 2011 12:55:01 -0400 Message-ID: References: <1817564019.180377.1319247876337.JavaMail.root@zimbra-prod-mbox-2.vmware.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from void.printf.net ([89.145.121.20]:36432 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752073Ab1JVQzJ (ORCPT ); Sat, 22 Oct 2011 12:55:09 -0400 In-Reply-To: (Linus Walleij's message of "Sat, 22 Oct 2011 18:33:57 +0200") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Linus Walleij Cc: Andrei Warkentin , Ulf Hansson , Per Forlin , Lee Jones , Johan Rudholm , John Beckett , linux-mmc@vger.kernel.org Hi Linus, On Sat, Oct 22 2011, Linus Walleij wrote: > So what about a cmdline approach? That makes it possible > for people who are willingly recompiling and hacking their kernels > to tinker with this if they absolutely want to go in on that > partition, make it rw and change stuff. > > ...org have I just got all this backwards...? Regarding this patch, we're not so worried that someone will take a read-only boot partition and make it read-write and do something wrong; sysfs is good enough to protect against that happening (at least by mistake). What we're worried about is someone issuing the perm read-only command, and not realizing that it really means that they can never ever write any more changes to their eMMC -- it's a one-time fuse -- and perhaps further not realizing that this may make their expensive cell phone become a brick of some sort, depending on how much the bootloader or OS depends on having r/w access. I don't even know that I'd want to make such an option available via a boot argument, since boot arguments are often misunderstood. As Andrei says, it doesn't sound like something a regular user (as opposed to an OEM) should ever have reason to do. I'd rather leave it to specialized manufacturing equipment. Does that make sense? Thanks, - Chris. -- Chris Ball One Laptop Per Child