The rEFInd Boot Manager:
The Future of rEFInd
by Roderick W. Smith, rodsmith@rodsbooks.com
Originally written: 3/14/2012; last Web page update:
6/8/2014, referencing rEFInd 0.8.2
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This page is part of the documentation for the rEFInd boot manager. If a Web search has brought you here, you may want to start at the main page.
rEFInd is far from perfect. It's based on rEFIt, which has a list of active bugs on its project page on Sourceforge. I have not studied this bug list in detail for rEFInd's first release, although I've probably fixed a few of those bugs because I encountered them myself. Other bugs I may never fix because I lack the necessary hardware for testing.
This page exists to document some of rEFInd's known bugs and limitations, as well as features I hope to add in the future. Some of the items on this list are things that you may be able to help with, so if you'd like to contribute, feel free to drop me a line!
The following list groups things that need to be done into broad categories. In some cases, there's some ambiguity about how an item might best be classified. Without further ado, then:
- Tasks with which non-programmers can help:
- Testing! rEFIt was complex enough that changes such as the ones
I've made have the potential to disrupt the program's operation in
unexpected ways. Since the initial 0.2.0 release, I've continued to
add features to rEFInd, and every new feature is another way for
bugs to get into the program. I can only test on a handful of
systems with a limited number of configurations. Therefore, if you
try rEFInd and run into bugs, please report them to me!
- rEFIt's original design, and hence rEFInd's design, enables easy
theming by replacing icon files. If you'd like to design a new
theme for rEFInd, feel free to submit it. I might or might not
replace the icons it uses now (most of which come from the Oxygen
Icons package), but I may provide links to themes on this Web site
(or even host them on the project's Sourceforge page). For more
information on designing themes for rEFInd, see the Theming rEFInd page.
- Improvements to existing features:
- The support for booting legacy (BIOS) OSes on UEFI-based PCs
currently has a number of limitations. Most importantly, it works
off of the list of boot devices stored in the computer's NVRAM. I'd
prefer to have it scan disks and partitions, as the Mac's legacy
boot support does. Also, the UEFI legacy boot code presents empty
optical drives and uses generic icons rather than OS-specific
icons.
- Currently, rEFInd can detect whether it's compiled for x86
or x86-64 systems and displays this information in its
"About" screen (AboutrEFInd() in main.c). I'd
like to add detection for Itanium and ARM systems, but I have no
way to test such changes.
- Further to the preceding, rEFInd's GPT-scanning code (used to
extract partition names) includes assumptions about byte order, and
so will work only on little-endian CPUs such as the x86 and
x86-64.
- A way to set the color of the font would be useful for theming
purposes.
- The program's font features could be greatly improved by enabling
use of a standard font format, by enabling use of non-ASCII
characters, and by enabling use of variable-width as well as
monospace fonts.
- The default_selection might be expanded to support some
form of specification of disk types, as in a special entry for any
optical disk or any external disk, no matter what its name is.
- It would be useful to be able to specify paths to boot loaders
and/or initial RAM disks relative to the rEFInd directory (or the
boot loader's directory, in the case of initrds).
- Currently the background for certain subscreens (such as the
information page or submenu listings) is a solid color based on the
upper-left corner of the screen. Having an option to support a
transparent background is desirable to some users.
- Known bugs that need squashing:
- I've been receiving reports of blank screens when using rEFInd on
some recent Mac models. I've investigated this with the help of one
user, and I suspect that Apple has made changes to its firmware
that are likely to affect just about any EFI program. I don't have
a definitive solution, but at least one user has reported that
removing rEFInd's drivers has caused the problem to go into
remission.
- The Gigabyte
Hybrid EFI has a bug that causes the allegedly case-insensitive
StriCmp() function to perform a case-sensitive comparison.
This causes any number of bugs in file matching. For instance:
Changing the case of icon filename extensions (or various other
parts of icon filenames) causes icons to be replaced by ugly
"generic" ones; and rEFInd sometimes appears in its own menu (the
firmware sometimes returns an all-caps version of the filename, but
other times returns the filename with the correct case, causing a
mismatch if the path includes lowercase elements). Some of these
problems can be overcome by converting both strings to be compared
to one case before doing the comparison, but others aren't so easy,
since I think StriCmp() is being called internally to the
EFI. In any event, it'd be nice to fix some of these problems.
OTOH, this is a workaround for a bug on just one EFI
implementation, and a dismal one at that, so I'm inclined to just
let it go.
- The Shutdown option works correctly on Macs, but not on many UEFI-based
PCs. On such systems, Shutdown reboots the computer. This should be
fixed.
- The media-ejection feature (F12) should be extended to work on
UEFI-based PCs and early Macs. At the moment, it relies on an
Apple-specific EFI extension, and I know of no standard EFI way to
do it.
- A couple of Mac users have reported that the brightness-adjustment
features in Windows don't work when Windows is booted via rEFInd,
but that these features do work when Windows is booted via the
Mac's built-in boot manager. Unfortunately, I have no idea what
causes this problem, I have no Windows installation on my one
(elderly) Mac, and I have no way to debug it. Therefore, it's
unlikely that I'll be able to fix this problem myself; but if you
have the equipment and skill to do so, I'd be interested in
receiving a patch.
- The re-scan feature occasionally produces odd results, such as
ignoring new media or keeping old media that have been ejected.
This should be investigated and fixed.
- The "scanning for new boot loaders" message that appears during the
re-scan feature is primitive. Some sort of dynamic icon would be
nice, but perhaps impractical, given the single-tasking nature of
EFI.
- On my Mac Mini, launching a shell, returning, and performing a
re-scan causes the system to be unable to launch the shell again. I
have not observed this behavior on UEFI-based PCs. It seems to be
caused by a truncated DevicePath to the shell, which includes the
shell's pathname but not the device identifier.
- When specifying a volume by name in dont_scan_dirs,
slashes are converted to backslashes in the specification but not
in the actual volume name read from disk. Thus, you can't specify a
volume by name if it includes a slash (as in Fedora
/boot). Workarounds are to rename the volume to omit the slash
and to use a filesystem number rather than a volume label.
- The code is in need of review to search for memory leaks and
similar problems.
- If the user has a Linux software RAID 1 array with Btrfs, HFS+,
or FAT filesystem, rEFInd will detect kernels or boot loaders in
RAID 1 twice. Checks to prevent this with ext2/3/4fs and ReiserFS
already exist; these checks could be expanded to block such
duplication with more filesystems.
- Some Macs experience problems with waking up from suspend states
when rEFInd is installed. Unfortunately, I lack the hardware to
test and experiment with this (my only Intel-based Mac doesn't
exhibit this problem), so I can't fix this myself. Using
pmset to disable the autopoweroff option is
claimed
by some to at least partially fix the problem, though. Using
the --ownhfs installation option may also help in some
cases.
- If you activate BIOS-mode support on UEFI-based PCs, you may find
multiple copies of the BIOS-mode loaders added to your firmware's
boot manager. Only one copy shows up in rEFInd, though.
- New features I'd like to add:
- EFI supports network boots. rEFInd doesn't, but it would be nice if
it would.
- There's currently no way to create a manual boot stanza for a
BIOS-booted OS. This isn't a big priority for me personally, but I
can see how it could be for some people.
- I've received queries about rEFInd's ability to work with Apple's
whole-disk encryption scheme that's new with OS X 10.7.
Unfortunately, I lack the hardware to test this, but my
understanding is that it will work correctly if rEFInd is
installed in the ESP rather than on the Mac OS X root partition.
See this
forum thread for more information.
- I'd like to find a way to enable users to enter customizations for
boot options and then save them to the refind.conf file.
One possible way to implement this would be to have manual boot
stanzas override auto-detected boot loader definitions for the same
boot loader file.
- I have thoughts about creating an EFI configuration tool and
information utility—something to tell you about your hard
disks, enable you to manage MOKs, adjust boot loader priority in
the NVRAM, and so on. This would be useful in system maintenance
and in recovering from boot problems.
- An installation tool for the EFI environment would be useful.
A simple EFI shell script might work, but because this function
requires access to the bcfg command, this would work
only from a version 2 shell or if bcfg were implemented
as a standalone program. Another alternative would be a program
written in C.
- It should be possible to override specific auto-detected boot
loader settings—say, to disable one specific boot loader or
change its icon.
- The ability to rotate the display for users who rotate their
monitors would be helpful.
- A GUI configuration tool would be nice, but it's low on my personal
priority list. If you'd like to contribute, I prefer something
written in a cross-platform GUI toolkit, so that a single code base
can be used on any of the major OSes.
- Improvements to the EFI drivers:
- Drivers for additional filesystems are desirable. Only XFS and JFS
are missing from the major Linux filesystems. UDF would also be a
welcome addition, as might drivers for other OSes (say, for the
BSDs, especially if BSD developers create a boot loader similar to
Linux's EFI stub loader). Also along these lines, adding drivers
for Linux LVM and RAID setups would be useful.
- This may not be possible, or it may require a new driver, but a way
to have the drivers access files (like a Linux loopback mount) is
desirable.
- When built with the GNU-EFI package, an attempt to load more than
one driver on my 32-bit Mac Mini causes the computer to hang. I do
not have this problem with 64-bit drivers on my UEFI-based
computers. I don't know if this is a 32-bit issue or a Mac issue.
This is not relevant if you're using my binary package,
since I build it with the TianoCore EDK2, and the drivers built in
that way don't exhibit this bug.
- Improvements to gptsync, install.sh, or other
support tools:
- The gptsync program can return misleading error codes
under some circumstances, such as when it makes no changes to the
partition table. Fix this.
- When updating a system with Secure Boot via an RPM or Debian
package, the RPM installation script can detect rEFInd's existing
shim or PreLoader program and pass options to install.sh
to try to copy these programs over themselves. This results in a
message that the copy was over the same file and an error message
that there were problems with the installation, although this isn't
really the case.
- A Mac-specific package is highly desirable.
copyright © 2012–2014 by Roderick W. Smith
This document is licensed under the terms of the GNU Free Documentation License (FDL), version 1.3.
If you have problems with or comments about this Web page, please e-mail me at rodsmith@rodsbooks.com. Thanks.
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