From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnout Vandecappelle Date: Thu, 21 Mar 2013 18:25:54 +0100 Subject: [Buildroot] Creating JFFS2 rootfs to SPI flash, and mounting it from kernel In-Reply-To: References: Message-ID: <514B42A2.6090808@mind.be> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net On 18/03/13 07:45, Juha Lumme wrote: > 1) My board is described in dtb file, so is it correct to assume that I > should also describe my flash layout there under the SPI section for the > flash ? It's either in the DTB or you can pass it along as boot arguments, something like: mtdparts=dataflash0:128k(u-boot),4m(kernel),12m(rootfs),-(home) > My planned layout is something like this (please ignore the addresses > themselves): > 0x0 - 0x9 u-boot > 0x10 - 0x19 kernel > 0x20 - 0x29 root fs > 0x30 - 0x39 /home > > 2) Currently I am passing the partition info on the memory card to the > kernel from u-boot (noinitrd console=ttyAMA0,115200 root=/dev/mmcblk0p2 > rw rootwait). > Can I now change this to: "noinitrd console=ttyAMA0,115200 > root=/dev/mtdblock2 rootfstype=jffs2 ro rootwait" ? > I'm thinking the block2 is since block 0 is u-boot and 1 would be kernel > ? ro instead of rw since I don't want to write to root fs. > Or does that make any sense ? What would you recommend me to do ? Is > JFFS2 a good idea ? Should I consider RAMFS for root file system ? JFFS2 as a read-only rootfs works perfectly. If you want to explore alternatives, consider UBI/UBIFS, but that's a bit more complex to set up. > 3) Where can I tell my kernel to mount /home as a separate file system ? > I would like that one to be read write, but I only rarely need to save > configuration files there... What would be a good idea with this ? In /etc/fstab. Create a target rootfs overlay with a custom fstab that specifies to mount /dev/mtdblok3 on /home. Note that you'll have to manually create a (supposedly empty) jffs2 filesystem on /dev/mtdblock3. Regards, Arnout -- Arnout Vandecappelle arnout at mind be Senior Embedded Software Architect +32-16-286500 Essensium/Mind http://www.mind.be G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle GPG fingerprint: 7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F