From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCHv4] MMC: MMC boot partitions support. Date: Fri, 1 Apr 2011 12:38:02 +0200 Message-ID: <201104011238.02551.arnd@arndb.de> References: <1300533491-2378-2-git-send-email-andreiw@motorola.com> <201103311317.22110.arnd@arndb.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.171]:49160 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754231Ab1DAKiH (ORCPT ); Fri, 1 Apr 2011 06:38:07 -0400 In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Andrei Warkentin Cc: linux-mmc@vger.kernel.org On Thursday 31 March 2011, Andrei Warkentin wrote: > On Thu, Mar 31, 2011 at 6:17 AM, Arnd Bergmann wrote: > > > > My feeling is that these should be separate from the boot partition. > > It could probably be done using a new fs/partitions/mmc.c file > > that directly interacts with the mmc layer instead of looking > > at the MS-DOS master boot record. That way, you could define the > > same partitions (mmcblk0p1, ...) using a different method. > > Nope. The device partitions are one time programmable (partition > once), so you definitely don't want to expose them as regular > partitions. The point > behind the GP partitions is that they can be implemented with enhanced > features (such as better reliability), and so like the enhanced area, > are meant as a complement, not a replacement for file system > partitions. > > I don't think there is a need to over complicate this. It's just going > to get more confusing and involve more changes. The device > partitioning support is pretty orthogonal right now. Even if they are write-once, wouldn't we still need to provide an interface to write them once? The question if GP should be used together or instead of MS-DOS partitions depends on the possible use cases. If you don't want to partition a GP any further in software, exposing them directly as mmcblk0pX would be a very nice and simple interface, but it completely prevents you from creating subpartitions. The other alternative is to allow each GP to contain a partition table, but then you need a either a three-level naming (mmcblk0gp1p2) or make each GP a device by itself (mmcblk0, mmcblk1) that can in turn be partitioned. > > Regarding the naming, I would not use a trailing zero, but it's probably > > a subjective thing. The other names I could imagine for the boot partition > > of mmc 0 are mmcboot0, mmcblk0b or mmcblk0boot. > > > > Since we have two boot partitions and 4 GP ones, for mmcblk0 I'd stick > with something like > mmcblk0boot0, mmcblk0boot1, mmcblk0gp0-mmcblk0gp4. I'd want to keep > the first mmcblk0, so that > a user can easily associate the actual card the device partitions are for. I would find it rather confusing if the device can be partitioned in software but the GP devices could not be. Arnd