From: Andreas Dilger Subject: Re: flashing large eMMC partitions with ext4 Date: Fri, 22 Jul 2011 10:35:20 -0600 Message-ID: <419A2628-5AF6-4B32-85B8-BE1E2B159DFA@gmail.com> References: <20110722154936.30251.qmail@web4208.mail.ogk.yahoo.co.jp> Mime-Version: 1.0 (iPhone Mail 8J2) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: "linux-ext4@vger.kernel.org" To: Round Robinjp Return-path: Received: from mail-pz0-f42.google.com ([209.85.210.42]:61587 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750927Ab1GVQe5 convert rfc822-to-8bit (ORCPT ); Fri, 22 Jul 2011 12:34:57 -0400 Received: by pzk37 with SMTP id 37so3832500pzk.1 for ; Fri, 22 Jul 2011 09:34:56 -0700 (PDT) In-Reply-To: <20110722154936.30251.qmail@web4208.mail.ogk.yahoo.co.jp> Sender: linux-ext4-owner@vger.kernel.org List-ID: If you can wipe the MMC device to be all-zero efficiently, then you can format it quickly with "mke2fs -E lazy_itable_init,lazy_journal_init ..." and restore from a tarball. Alternately, Lukas recently added support for QCOW2 sparse image format, and it should be possible to restore this to the device efficiently, if it is zeroed in advance. I don't know if his code skips all-zero blocks in the image, but that should be possible to add fairly easily. Cheers, Andreas On 2011-07-22, at 9:49 AM, Round Robinjp wrote: > Hi > > I have a question regarding making ext4 image for > large eMMC partition. > > We have a 4G partition in our embedded device > in which we want to use ext4 filesystem. > But for that we have to create a 4G image. > flashing this 4G image to the eMMC takes a long > time. Is there any way to reduce this time? > > For vfat, you can truncate the image leaving only > non zero-filled blocks which makes the image very > short and the time for flashing is reduced. > Is something similar to that possible for ext4? > > Thanks > Robin > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html