Difference between revisions of "Create a FLASH partition to store user's HOME"

Revision as of 15:36, 25 February 2015

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

Warning: You may loose the content of your current rootfs partition if going further. So be sure to have backuped your data before.

APF27

APF9328

APF27

APF51

APF28

* 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.0:1M(u-boot)ro,512K(env),512K(env2),512k(firmware),512K(dtb),5M(kernel),200M(rootfs),-(user)
BIOS> setenv addubifsargs 'setenv bootargs ${bootargs} ubi.mtd=rootfs ubi.mtd=user root=ubi0:rootfs rootfstype=ubifs'
BIOS> printenv mtdparts
mtdparts=mtdparts=mxc_nand.0:1M(u-boot)ro,512K(env),512K(env2),512k(firmware),512K(dtb),5M(kernel),200M(rootfs),-(user)

Erase the created partition (which now starts at (rootfs_offset + rootfs_len) = 0x0CE80000: (U-Boot 1.3.4)

U-Boot 1.3.4:

BIOS> nand erase 0x0CE80000

U-Boot 2011.12:

BIOS> nand erase.part user

Save your changes, update the rootfs partition (U-Boot 2011.12) and boot Linux:

* Check your NAND FLASH size:

BIOS> reset
U-Boot 2013.04 (...

NAND:  512 MiB
...

So here we have 512 MBytes. Then check current partitionning:

BIOS> printenv mtdparts
mtdparts=mtdparts=mxc_nand:1M(u-boot)ro,512K(env),512K(env2),1M(firmware),512K(dtb),512K(splash),8M(kernel),-(rootfs)

Here we have the default APF51 partitionning scheme (rootfs of 500 MBytes). Now I will reduce rootfs size to 450 MBytes (0x1c200000 in hexa) and so have the remaining (50 MBytes) for my "user" partition:

BIOS> setenv mtdparts 'mtdparts=mxc_nand:1M(u-boot)ro,512K(env),512K(env2),1M(firmware)
,512K(dtb),512K(splash),8M(kernel),450M(rootfs),-(user)'

BIOS> nand erase.part user

NAND erase.part: device 0 offset 0x1ce00000, size 0x3200000
OK

BIOS> setenv addubifsargs 'setenv bootargs ${bootargs} ubi.mtd=rootfs ubi.mtd=user
root=ubi0:rootfs rootfstype=ubifs'

BIOS> saveenv
BIOS> run update_rootfs
BIOS> boot

Linux

In Linux boot message you should see your newly created partition is detected:

Boards with U-Boot 1.3.4 (offset may vary)

All boards with U-Boot >= 2013.xx (offset may vary)

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"

9 cmdlinepart partitions found on MTD device mxc_nand
Creating 9 MTD partitions on "mxc_nand":
0x000000000000-0x000000100000 : "u-boot"
0x000000100000-0x000000180000 : "env"
0x000000180000-0x000000200000 : "env2"
0x000000200000-0x000000300000 : "firmware"
0x000000300000-0x000000380000 : "dtb"
0x000000380000-0x000000400000 : "splash"
0x000000400000-0x000000c00000 : "kernel"
0x000000c00000-0x00001ce00000 : "rootfs"
0x00001ce00000-0x000020000000 : "user"

you can also see it in /proc/mtd (here for example on an APF28 + U-Boot 2012.02 system):

Example for APF28 with U-Boot 2012.02

Example for APF51 with U-Boot 2013.04

# cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 00300000 00020000 "u-boot"
mtd1: 00080000 00020000 "env"
mtd2: 00080000 00020000 "env2"
mtd3: 00080000 00020000 "dtb"
mtd4: 00080000 00020000 "splash"
mtd5: 00800000 00020000 "kernel"
mtd6: 1c200000 00020000 "rootfs"
mtd7: 03200000 00020000 "user"

# cat /proc/mtd 
dev:    size   erasesize  name
mtd0: 00100000 00020000 "u-boot"
mtd1: 00080000 00020000 "env"
mtd2: 00080000 00020000 "env2"
mtd3: 00100000 00020000 "firmware"
mtd4: 00080000 00020000 "dtb"
mtd5: 00080000 00020000 "splash"
mtd6: 00800000 00020000 "kernel"
mtd7: 1c200000 00020000 "rootfs"
mtd8: 03200000 00020000 "user"

Check a device node was created for your new partition (U-Boot 1.3.4: /dev/mtdblock5 - U-Boot 2011.12: /dev/mtdblock7):

# 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 (U-Boot 1.3.4: /dev/mtdblock5 - U-Boot 2011.12: /dev/mtdblock7). It will be automatically formatted to JFSS2:

# mkdir /tmp/nand
# mount -t jffs2 /dev/mtdblock7 /tmp/nand
# ls /tmp/nand/

For UBIFS: create a temporary mount point, format and mount the partition (U-Boot 1.3.4: replace mtd7 by mtd5 and '-m 7' by '-m 5'):

# mkdir /tmp/nand
# ubiformat /dev/mtd7
# ubiattach /dev/ubi_ctrl -m 7
# ubimkvol /dev/ubi1 -s 40MiB -N user
# mount -t ubifs ubi1:user /mnt/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:

JFFS2:

# vi /etc/fstab
...
sysfs           /sys           sysfs    defaults          0      0        
usbfs           /proc/bus/usb  usbfs    defaults          0      0
/dev/mtdblock7  /root          jffs2    defaults          0      0   <<-----------------

UBIFS:

# vi /etc/fstab
...
sysfs           /sys           sysfs    defaults          0      0        
usbfs           /proc/bus/usb  usbfs    defaults          0      0
ubi1:user       /mnt/nand      ubifs    defaults,noatime,rw    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/mtdblock7           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 !

@@ Line 88: / Line 88: @@
 ==Linux==
 * In Linux boot message you should see your newly created partition is detected:
-{| border="1" cellpadding="10" cellspacing="0" summary="PWM usage depending on kernel version" class="wikitable"
+{| border="1" cellpadding="10" cellspacing="0" summary="MTD boot log" class="wikitable"
 |- style="background:#efefef;" align="center"
 ! Boards with U-Boot 1.3.4 (offset may vary) || All boards with U-Boot >= 2013.xx (offset may vary)
@@ Line 118: / Line 118: @@
 * you can also see it in ''/proc/mtd'' (here for example on an APF28 + U-Boot 2012.02 system):
-<pre class="apf">
+{| border="1" cellpadding="10" cellspacing="0" summary="/proc/mtd" class="wikitable"
+|- style="background:#efefef;" align="center"
+! Example for APF28 with U-Boot 2012.02 || Example for APF51 with U-Boot 2013.04
+|--------
+|<pre class="apf">
 # cat /proc/mtd
 dev:    size   erasesize  name
@@ Line 127: / Line 131: @@
 mtd4: 00080000 00020000 "splash"
 mtd5: 00800000 00020000 "kernel"
-...
+mtd6: 1c200000 00020000 "rootfs"
+mtd7: 03200000 00020000 "user"
 </pre>
+|
+<pre class="apf">
+# cat /proc/mtd
+dev:    size   erasesize  name
+mtd0: 00100000 00020000 "u-boot"
+mtd1: 00080000 00020000 "env"
+mtd2: 00080000 00020000 "env2"
+mtd3: 00100000 00020000 "firmware"
+mtd4: 00080000 00020000 "dtb"
+mtd5: 00080000 00020000 "splash"
+mtd6: 00800000 00020000 "kernel"
+mtd7: 1c200000 00020000 "rootfs"
+mtd8: 03200000 00020000 "user"
+</pre>
+|}
 * Check a device node was created for your new partition '''(U-Boot 1.3.4: ''/dev/mtdblock5'' - U-Boot 2011.12:  ''/dev/mtdblock7'')''':

Difference between revisions of "Create a FLASH partition to store user's HOME"

Revision as of 15:36, 25 February 2015

Declare partition in U-Boot

APF27

Linux

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