Create a FLASH partition to store user's HOME
From ArmadeusWiki
If you ever did some hacking/devt on your APF board and used /root/ to download or install your experiments, I'm sure you got frustrated when it comes the time where you had to reflash the whole rootfs. Indeed, by default, /root/ is located in the same partition as the rootfs image and so everything you did will be overwritten. Well, you can always backup your data on a SD/microSD or through NFS before doing the rootfs flashing, but I think that, like me, you are little bit lazy ;-).
So in this small tutorial I will explain you how to modify the FLASH setup to store your personnal data on a separated partition and so avoid the backup process when updating your rootfs.
Declare partition in U-Boot
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Warning: You may loose the content of your current rootfs partition if going further. So be sure to have backuped your data before. |
APF27
- Check your NAND FLASH size:
BIOS> nand info Device 0: NAND 256MiB 1,8V 16-bit, sector size 128 KiB
- So here I have 256MBytes. Then check current partitionning:
BIOS> printenv mtdparts mtdparts=mtdparts=mxc_nand.0:640k(U-boot)ro,384k(U-boot_env),512k(firmware),5M(kernel),-(rootfs)
- I have the default APF27 partitionning scheme. Now I will reduce rootfs size to 200 MBytes (0x0C800000 in hexa) and so have the remaining (50 MBytes) for my "user" partition:
U-Boot 1.3.4:
BIOS> setenv mtdparts mtdparts=mxc_nand.0:640k(U-boot)ro,384k(U-boot_env),512k(firmware),5M(kernel),200M(rootfs),-(user) BIOS> printenv mtdparts mtdparts=mtdparts=mxc_nand.0:640k(U-boot)ro,384k(U-boot_env),512k(firmware),5M(kernel),200M(rootfs),-(user) BIOS> setenv rootfs_len 0x0C800000
U-Boot 2011.12:
BIOS> setenv mtdparts mtdparts=mxc_nand.0:640k(U-boot)ro,384k(U-boot_env),512k(firmware),5M(kernel),200M(rootfs),-(user) BIOS> printenv mtdparts mtdparts=mtdparts=mxc_nand.0:640k(U-boot)ro,384k(U-boot_env),512k(firmware),5M(kernel),200M(rootfs),-(user)
- Erase the created partition (which now starts at (rootfs_offset + rootfs_len) = 0x0CE80000:
U-Boot 1.3.4:
BIOS> nand erase 0x0CE80000
U-Boot 2011.12:
BIOS> nand erase.part user* Save your changes and boot Linux:
BIOS> saveenv BIOS> boot
APF9328/APF51/APF28
TODO
Linux
- In Linux boot message you should see you newly created partition detected:
6 cmdlinepart partitions found on MTD device mxc_nand.0 Creating 6 MTD partitions on "mxc_nand.0": 0x000000000000-0x0000000a0000 : "U-boot" 0x0000000a0000-0x000000100000 : "U-boot_env" 0x000000100000-0x000000180000 : "firmware" 0x000000180000-0x000000680000 : "kernel" 0x000000680000-0x00000ce80000 : "rootfs" 0x00000ce80000-0x000010000000 : "user"
- Check a device node was created for your new partition (/dev/mtdblock5):
# ls /dev/mtdblock* /dev/mtdblock0 /dev/mtdblock2 /dev/mtdblock4 /dev/mtdblock1 /dev/mtdblock3 /dev/mtdblock5
- For JFFS2: create a temporary mount point and mount the partition. It will be automatically formatted to JFSS2:
# mkdir /tmp/nand # mount -t jffs2 /dev/mtdblock5 /tmp/nand # ls /tmp/nand/
- For UBIFS: create a temporary mount point, format and mount the partition:
# mkdir /tmp/nand # ubiformat /dev/mtd5 # ubiattach dev/ubi_ctrl -m 5 # mount -t ubifs ubi1 /tmp/nand # ls /tmp/nand/
- Move your user data to the partition:
# cp -r /root/* /tmp/nand/ # cp -r /root/.[ab]* /tmp/nand/
- Makes it automatically mounted at every boot by adding it to /etc/fstab:
# vi /etc/fstab ... sysfs /sys sysfs defaults 0 0 usbfs /proc/bus/usb usbfs defaults 0 0 /dev/mtdblock5 /root jffs2 defaults 0 0 <<-----------------
- Now you're done. Reboot and enjoy ! ;-)
# reboot ... # df -h Filesystem Size Used Available Use% Mounted on rootfs 200.0M 17.8M 182.2M 9% / /dev/root 200.0M 17.8M 182.2M 9% / none 64.0k 0 64.0k 0% /dev tmpfs 61.2M 44.0k 61.1M 0% /tmp >>> /dev/mtdblock5 49.5M 4.0M 45.5M 8% /root <<< # ls /root/
- Of course if you reflash your rootfs, even if you keep your personnal data, you will have to repeat the /etc/fstab modification step above !
