= Ext4fs = Ext2, Ext3 and Ext4,respectively, are forward-compatible file systems originally designed for the Linux kernel and now supported by HelenOS. The read-only Ext2 support was implemented in 2011 by Martin Sucha. In 2012, FrantiĊĦek Princ implemented for some, but not all, features of Ext3 and Ext4, including write support.