Ext4

ext4 is an open source disk filesystem and the most recent version of the ext series.

Kernel
You need to activate the following kernel options:

Software
contains the utilities to work with the filesystem. It's part of the system set and so already installed on your system.

You can change the USE flags:

After setting this you want to update your system so the changes take effect:

Creation
To create an ext4 filesystem on the partition:

Please replace with the actual partition you want to format.

Mount
You can mount the filesystems in several ways:
 * mount - Manual mount.
 * fstab - Automatic mount at boot time.
 * removable media - Automatic mount at demand.
 * AutoFS - Automatic mount on access.

External resources

 * ext4 Wiki