href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com</a></p>
<p>Originally written: 4/19/2012; last Web page update:
-3/9/2014, referencing rEFInd 0.7.8</p>
+5/15/2014, referencing rEFInd 0.8.1</p>
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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
+ can handle ext2fs and ext3fs, too. Providing both drivers enables
+ easy filesystem separation—for instance, you can use ext2fs on a
+ <tt>/boot</tt> partition and ext4fs on your root (<tt>/</tt>)
+ partition, to have the EFI scan only the former. 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>
+ 2.0 Btrfs driver. 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>
<li><b>ISO-9660</b>—This driver originated with rEFIt's author, but
he never released a final version. Its code was improved by Oracle for