From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from wa-out-1112.google.com ([209.85.146.179]) by bombadil.infradead.org with esmtp (Exim 4.68 #1 (Red Hat Linux)) id 1JK6Zl-0000AB-1a for linux-mtd@lists.infradead.org; Wed, 30 Jan 2008 06:37:44 +0000 Received: by wa-out-1112.google.com with SMTP id v33so195947wah.2 for ; Tue, 29 Jan 2008 22:37:30 -0800 (PST) Message-ID: <47A01B22.9040206@gmail.com> Date: Wed, 30 Jan 2008 01:37:22 -0500 From: Max Stirling MIME-Version: 1.0 To: linux-mtd@lists.infradead.org Subject: Re: mtd block readonly low level nand driver cramfs References: <47985D88.1060005@gmail.com> <6a61dac20801270054t19e2af20o1211490d104110a9@mail.gmail.com> <479D86E4.30903@gmail.com> In-Reply-To: <479D86E4.30903@gmail.com> Content-Type: multipart/mixed; boundary="------------020806050905060107050203" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This is a multi-part message in MIME format. --------------020806050905060107050203 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Max Stirling wrote: > Max Stirling wrote: >> I was looking at the chips folder under MTD and the MTD_ROM flag >> settings. >> >> I got this idea of having this low level driver code under chips with >> the MTD_ROM flag set and mounting this for cramfs. >> >> Please comment, especially folks using the RO FS mounted on flash. >> >> MS >> >> On Jan 24, 2008 3:12 PM, Max Stirling wrote: >> >>> Hi, >>> >>> This might sound quite basic question. This is the first time I am >>> looking into the MTD code so have some really basic questions. >>> >>> I am trying to mount a read only fs (cramfs) on the flash. Please >>> let me >>> know if the following steps are right: >>> >>> 1. Enabled the following in the Kconfig files >>> CONFIG_MTD_PARITIONS >>> CONFIG_MTD >>> CONFIG_MTD_BLOCK_RO >>> CONFIG_MTD_NAND >>> CONFIG_MTD_NAND_IDS >>> >>> >>> After booting the compiled kernel I am able to see the mtdblock under >>> /proc/devices using 31 Major number. >>> >>> Now for me to mount the cramfs image that is on the flash I need to >>> provide the low level nand driver code. This I need to write but before >>> starting that can any one point me to a reference nand driver code that >>> is used for read only mount? Which functionality would the MTD require >>> to be implemented for mounting a cramfs image which is on the flash. >>> >>> Would appreciate any pointers to how to get started off with this. >>> >>> thanks in advance for the reply. >>> >>> M.S >>> >>> >>> > When using the cramfs as the fs for the flash and mtdblock_ro enabled. > Which one should I be calling the user module, the cramfs or the > mtdblock_ro? > > I have enabled the mtdblock_ro module and written a low lever chip driver code. Since I am mounting this as read-only I have set the type in mtd_info to MTD_ROM. When I do a mount using command # mount -t cramfs /dev/mtdblock mnt_cramfs . mtdblock_ro.c mtdblock_readsect mtdblock_ro.c mtdblock_readsect mtdblock_ro.c mtdblock_readsect mtdblock_ro.c mtdblock_readsect . mount: Mounting /dev/mtdblock on cramfs failed: Invalid argument. I created a cramfs image using cramfs utility and written that to flash. I tested the cramfs image by mounting on my local machine. Is there anything that is missing here? --------------020806050905060107050203 Content-Type: text/x-vcard; charset=utf-8; name="vicky_irobot.vcf" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="vicky_irobot.vcf" begin:vcard fn:M S n:S;M version:2.1 end:vcard --------------020806050905060107050203--