+<li><b>Ext4fs</b>—Stefan Agner <a
+ href="https://github.com/falstaff84/rEFInd">modified the rEFIt/rEFInd
+ ext2fs driver</a> so that it could handle ext4fs. I'm including this as
+ a separate driver from the ext2fs driver, although the ext4fs version
+ can handle ext2fs and ext3fs, too. (I may eventually retire the
+ original ext2fs driver, but I want to be conservative about this in
+ case there's an undiscovered problem with the new driver.) This driver
+ has some limitations. Most notably, for various reasons it maxes out at
+ 16TiB and won't mount any ext4 filesystem that's larger than this. As
+ of version 0.6.1, this driver supports the <tt>meta_bg</tt> feature,
+ which can also be used on ext2fs and ext3fs. Thus, it can handle some
+ ext2fs and ext3fs partitions that the ext2fs driver can't handle. You
+ can learn about your ext2/3/4 filesystem features by typing <tt
+ class="userinput">dumpe2fs <i>/dev/sda2</i> | grep features</tt>,
+ changing <tt class="userinput"><i>/dev/sda2</i></tt> to your
+ filesystem's device.</li>
+
+<li><b>Btrfs</b>—</b>Samuel Liao contributed this driver, which is
+ based on the rEFIt/rEFInd driver framework and algorithms from the GRUB
+ 2.0 Btrfs driver. As of rEFInd 0.7.0, this driver is new and should be
+ considered experimental. I've tested this driver with a simple
+ one-partition filesystem and with a filesystem that spans two physical
+ devices (although I've made no attempt to ensure that the driver can
+ actually read files written to both devices). Lamuel Liao has used the
+ driver with a compressed Btrfs volume. The driver will handle
+ subvolumes, but you may need to add kernel options if you're booting a
+ Linux kernel directly from a filesystem that uses subvolumes. For
+ instance, on a test installation of Ubuntu 14.04 alpha on such a
+ system, I needed to set <tt>also_scan_dirs + @/boot</tt> in
+ <tt>refind.conf</tt> and add <tt>rootflags=subvol=@</tt> to the kernel
+ options in my <tt>refind_linux.conf</tt> file. Without the first of
+ these options, rEFInd could not locate my kernel; and without the
+ second, the boot failed with a message to the effect that the initial
+ RAM disk could not find <tt>/sbin/init</tt>.</li>
+