How can I extract the contents of a CRAMFS image file?

Extracting the contents of a CRAMFS image

To mount a CRAMFS image on a Linux workstation, you will need kernel support for the CRAMFS filesystem (CONFIG_CRAMFS; File systems -> Compressed ROM file system support) and loopback block devices (CONFIG_BLK_DEVICE_LOOP; Block devices -> loopback device support). The kernels for ADS embedded systems have CRAMFS support built-in; if you wish to avoid compiling a kernel, you can perform this process on your ADS board instead of a Linux PC.

To mount a CRAMFS image, use the command:

   mount -o loop -t cramfs image_file  /mount/point

Use 'tar' to copy the CRAMFS filesystem to a temporary directory:

   cd /mount/point
   tar -cf  -  . | tar -C /temporary/dir  -xpf  -

You will need to be 'root' to copy the files without losing the proper permissions.

Creating a new CRAMFS image

To create a CRAMFS image, you will need the 'mkcramfs' utility. Under Debian, you can install this program by running:

   apt-get install mkcramfs