Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
312 lines (202 sloc) 9.93 KB

Setting Up an SDCARD for /root and swap for Onion Omega2+

Generally on OpenWrt I like to mount a USB flash drive at /root for file and script storage. This is loosely based on various tutorials on the OpenWRT Wiki.

This was tested on a Onion Omega2+, but will probably work on the Omega2. I do not have access to an Omega1 to test it.

Install Packages

opkg update
opkg install fdisk kmod-fs-ext4 e2fsprogs swap-utils block-mount

Some Onion versions show an error when installing kmod-fs-ext4, you should update the the latest if you run into problems.

Finding the SDCARD

Then insert your sdcard and find it.

fdisk -l

There will be several entries, you are looking for something like this. I'm using an 8GB SD card, it recognizes it as 7.2 GiB.

Disk /dev/mmcblk0: 7.2 GiB, 7746879488 bytes, 15130624 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Take note of the /dev/mmcblk0 or whatever yours shows. If you use the wrong one you can screw up your device.

Unmounting the SDCARD

If your SDCARD is currently mounted, you will need to unmount it to modify the partition table.

umount /dev/mmcblk0

If you are not mounted it'll show this error.

umount: can't unmount /dev/mmcblk0: Invalid argument

Showing Free Memory and Swap

free

Should display something like this, note the swap currently shows 0 for all entries.

                    total       used       free     shared    buffers     cached
Mem:               125764      34096      91668        200       4024      12736
-/+ buffers/cache:  17336     108428
Swap:                   0          0          0

Create two Partitions

You will need to create two partitions on your SDCARD.

If your SDCARD already has a partition, it will show an error, which you can ignore.

fdisk /dev/mmcblk0

This section has several inputs which you'll need to make, I noted them in the code sections with ⟵⟵⟵.

Once in the fdisk program it will prompt you with this. I recommend hitting m to see the commands available.

Command (m for help):

You'll probably want to start with F to determine how much free space you have. I'm using an 8GB SDCARD, it shows:

Command (m for help): F ⟵⟵⟵
    Unpartitioned space /dev/mmcblk0: 7.2 GiB, 7745830912 bytes, 15128576 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Start      End  Sectors  Size
 2048 15130623 15128576  7.2G

Next up, create a 2GB swap partition with the n command. You will need to make several entries.

Command (m for help): n ⟵⟵⟵
Partition number (1,2,4-8, default 1): 1 ⟵⟵⟵


Partition type
p   primary (0 primary, 0 extended, 4 free)
e   extended (container for logical partitions)
Select (default p): p ⟵⟵⟵
Partition number (1-4, default 1): 1 ⟵⟵⟵
First sector (2048-15130623, default 2048): 2048 ⟵⟵⟵
Last sector, +sectors or +size{K,M,G,T,P} (2048-15130623, default 15130623): +2G ⟵⟵⟵

Created a new partition 1 of type 'Linux' and of size 2 GiB.

Now create the partition you'll use for /root, again with the n command, unless you are doing something special, you may just hit enter fore each of the prompts, I marked them anyway.

Command (m for help): n ⟵⟵⟵
Partition type
   p   primary (1 primary, 0 extended, 3 free)
   e   extended (container for logical partitions)
Select (default p): p ⟵⟵⟵
Partition number (2-4, default 2): 2 ⟵⟵⟵
First sector (4196352-15130623, default 4196352): 4196352 ⟵⟵⟵
Last sector, +sectors or +size{K,M,G,T,P} (4196352-15130623, default 15130623): 15130623 ⟵⟵⟵

Created a new partition 2 of type 'Linux' and of size 5.2 GiB.

Set the swap partition type to swap with the t command. Again you will need to make several entries.

Command (m for help): t ⟵⟵⟵
Partition number (1,2, default 2): 1 ⟵⟵⟵
Partition type (type L to list all types): 82 ⟵⟵⟵

Changed type of partition 'Linux' to 'Linux swap / Solaris'.

You may now print the partition table with the p command to verify what you have done. It should show something like this.

Command (m for help): p ⟵⟵⟵
Disk /dev/mmcblk0: 7.2 GiB, 7746879488 bytes, 15130624 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x95cb5374

Device         Boot   Start      End  Sectors  Size Id Type
/dev/mmcblk0p1         2048  4196351  4194304    2G 82 Linux swap / Solaris
/dev/mmcblk0p2      4196352 15130623 10934272  5.2G 83 Linux

If all looks good, write the partition with the w command.

Command (m for help): w ⟵⟵⟵
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

This will drop you back to the shell, run fdisk -l again and you should see your partitions have changed and shows something like this.

Disk /dev/mmcblk0: 7.2 GiB, 7746879488 bytes, 15130624 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x95cb5374

Device         Boot   Start      End  Sectors  Size Id Type
/dev/mmcblk0p1         2048  4196351  4194304    2G 82 Linux swap / Solaris
/dev/mmcblk0p2      4196352 15130623 10934272  5.2G 83 Linux

Take note of your Linux swap and Linux partition Devices.

Format the SDCARD

Format your Linux partition as ext4.

mkfs.ext4 /dev/mmcblk0p2

This will take a minute and output something like the following.

mke2fs 1.43.3 (04-Sep-2016)
Creating filesystem with 1366784 4k blocks and 342048 inodes
Filesystem UUID: 8d86e910-080a-41f2-b4da-bb66c425fe9d
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

Unfortunately I'm not certain how to format fat32 for you Windows guys & gals. Normally you'd use mkdosfs, but I'm not sure what package from opkg contains it. I don't use Windows at all any more, so I don't really have much use for fat32.

Format your Linux swap partition and enable the swap.

mkswap /dev/mmcblk0p1
swapon /dev/mmcblk0p1

View Swap Space

Again use the free command.

free -k

It should now show your updated swap space.

        total       used       free     shared    buffers     cached
Mem:   125764      30172      95592        200       4028       7488
-/+ buffers/cache: 18656     107108
Swap: 2097148          0    2097148

You may also use the swapon command to show your swap space.

swapon -s

This should display something like this.

Filename          Type        Size       Used   Priority
/dev/mmcblk0p1    partition   2097148    0      -1

Mount the /root Partition

If you have anything in your /root currently, move it to /tmp.

mkdir /tmp/root_temp
mv /root/* /tmp/root_temp
ls -lah /root

Mount the drive and try writing to it.

mount /dev/mmcblk0p2 /root
cd /root
echo "test" > test.txt
cat test.txt

This should display test. Now you can move your stuff back from /tmp to /root.

mv /tmp/root_temp/* /root
rmdir /tmp/root_temp/

Mount the SDCARD at Boot

Enable the fstab.

/etc/init.d/fstab enable

Detect the mounts.

block detect > /etc/config/fstab
cat /etc/config/fstab

This should display something similar to this, take note of your uuid, they are always different.

config 'global'
    option  anon_swap   '0'
    option  anon_mount  '0'
    option  auto_swap   '1'
    option  auto_mount  '1'
    option  delay_root  '5'
    option  check_fs    '0'

config 'swap'
    option  device  '/dev/mmcblk0p1'
    option  enabled '0'

config 'mount'
    option  target  '/mnt/mmcblk0p2'
    option  uuid    'YOUR-UUID-HERE'
    option  enabled '0'

You'll want to edit the fstab.

vi /etc/config/fstab

Make it look like this.

config 'global'
    option  anon_swap   '0'
    option  anon_mount  '0'
    option  auto_swap   '1'
    option  auto_mount  '1'
    option  delay_root  '5'
    option  check_fs    '0'

config 'swap'
    option  device  '/dev/mmcblk0p1'
    option  enabled '1'

config 'mount'
    option  target  '/root'
    option  uuid    'YOUR-UUID-HERE'
    option  enabled '1'

Reboot and exit.

reboot && exit

SSH back into the unit and make sure the mount worked

df -h

Should show something like this.

Filesystem                Size      Used Available Use% Mounted on
/dev/root                 5.5M      5.5M         0 100% /rom
tmpfs                    61.4M    184.0K     61.2M   0% /tmp
/dev/mtdblock6           25.1M      3.7M     21.4M  15% /overlay
overlayfs:/overlay       25.1M      3.7M     21.4M  15% /
tmpfs                   512.0K         0    512.0K   0% /dev
/dev/mmcblk0p2            5.1G     20.9M      4.8G   0% /root

Then check the swap.

swapon -s

Should still display something like this.

Filename            Type        Size      Used   Priority
/dev/mmcblk0p1      partition   2097148   0      -1

You may re-check your free space.

free

Should display something like this.

             total       used       free     shared    buffers     cached
Mem:        125764      35868      89896        200       5256      12732
-/+ buffers/cache:      17880     107884
Swap:      2097148          0    2097148

You are done.

...

You can’t perform that action at this time.