Creating a file-based SWAP on your Beagleboard

On the Beagleboard you should expect to require a swap file given the limitation of how little RAM is available (between 256 MB and 512 MB). Some system programs like apt-get will only run properly when some swap space is present (due to 256 MB not being enough RAM).

Some images (such as those from Linaro.org) do not come with a swap partition or any swap space allocated.

Under Linux, swap space can be either a dedicated partition or a swap file. Both can be mounted as swap which the OS can access.

Creating a Swapfile

The following commands will create a 512MB file, limit access only to root, format it as swap and then make it available to the OS:

sudo mkdir -p /var/cache/swap/   
sudo dd if=/dev/zero of=/var/cache/swap/swapfile bs=1M count=512
sudo chmod 0600 /var/cache/swap/swapfile 
sudo mkswap /var/cache/swap/swapfile 
sudo swapon /var/cache/swap/swapfile

To tell the OS to load this swapfile on each start up, edit the /etc/fstab file to include the following additional line:

/var/cache/swap/swapfile    none    swap    sw    0   0

To verify that the swapfile is accessilble as swap to the OS, run "top" or "htop" at a console.

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