href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com</a></p>
<p>Originally written: 3/14/2012; last Web page update:
-4/25/2013, referencing rEFInd 0.6.9</p>
+7/6/2014, referencing rEFInd 0.8.3</p>
-<p>I'm a technical writer and consultant specializing in Linux technologies. This Web page is provided free of charge and with no annoying outside ads; however, I did take time to prepare it, and Web hosting does cost money. If you find this Web page useful, please consider making a small donation to help keep this site up and running. Thanks!</p>
+<p>This Web page is provided free of charge and with no annoying outside ads; however, I did take time to prepare it, and Web hosting does cost money. If you find this Web page useful, please consider making a small donation to help keep this site up and running. Thanks!</p>
<table border="1">
<tr>
<li class="tight"><a href="#legacy">Booting Legacy OSes</a></li>
+<li class="tight"><a href="#delays">Reducing Startup Delays</a></li>
+
</ul>
</div>
height="552" alt="rEFInd presents a GUI menu for selecting your boot
OS." border=2 /></center> <br />
-<p>If you don't press any key before the timeout (shown below the icons and description line) expires, the default boot loader will launch. This is normally the first item in the menu, but you can adjust the default by editing the configuration file. (In this example, it's the Ubuntu Linux loader, which is further identified by text above the timeout as <i>vmlinuz-3.5.0-27-generic from UBUNTU BOOT</i>.)</p>
+<p>If you don't press any key before the timeout (shown below the icons and description line) expires, the default boot loader will launch. This is normally the item that you launched the last time rEFInd ran, but you can adjust the default by editing the configuration file. (In this example, it's the Ubuntu Linux loader, which is further identified by text above the timeout as <i>vmlinuz-3.5.0-27-generic from UBUNTU BOOT</i>.)</p>
<p>This display is dominated by the central set of OS <i>tags</i> (icons), which in this example includes tags for an unknown boot loader, OS X, Windows, and Ubuntu. All but the first of these are on hard disks, but the unknown boot loader is on an optical disc, as revealed by the small icons (known as <i>badges</i>) in the lower-right corner of the OS icons.</p>
</tr>
<tr>
<td><i>F10</i></td>
- <td>Saves an image of the current screen in the file <tt>screenshot.bmp</tt> in the ESP's root directory</td>
+ <td>Saves an image of the current screen in the file <tt>screenshot_<tt class="variable">###</tt>.bmp</tt>, where <tt class="variable">###</tt> is a sequence number starting with <tt>001</tt>, in the EFI System Partition's (ESP's) root directory</td>
</tr>
<tr>
<td><i>F12</i> or (on some keyboards) <i>Eject</i></td>
</tr>
</table>
+<p class="sidebar"><b>Note:</b> If you set <tt>timeout = -1</tt> in <tt>refind.conf</tt>, rEFInd will immediately launch the default OS <i>unless</i> you press a key as rEFInd launches. In that case, if the key you pressed is a valid shortcut key, rEFInd will launch the associated entry. If not, rEFInd will show you its main menu.</p>
+
<p>rEFInd assigns shortcut letters to most OS entries based on the first letter of the directory in which the OS's boot loader is stored. For instance, if you have a boot loader called <tt>/EFI/debian/elilo.efi</tt>, rEFInd attempts to assign it a shortcut letter of <i>D</i>. rEFInd overrides this default for Mac OS X, Windows, and for Linux's GRUB, ELILO, and EFI stub boot loaders if the distribution can't be more precisely identified, as noted in the preceding table. This method works well for many installations, but it can produce conflicts. For instance, if you have a Macintosh that holds both Mac OS X and Mandriva, both OSes would normally use the <tt>M</tt> shortcut key. In practice, which works depends on the order in which rEFInd detects the OSes.</p>
<a name="legacy">
<p>For all such cases, rEFInd supports booting legacy OSes; however, the details vary between Macs and UEFI PCs. Also, be aware that some UEFI PCs lack the Compatibility Support Module (CSM) that's required for this feature to work. This is true even of some computers that can boot BIOS-based OSes natively. This can happen because the firmware is basically a BIOS with a UEFI implementation tacked on top of it; such systems rely on the native BIOS to boot, and may not provide a way for EFI applications to access the BIOS features via CSM mechanisms. If you have such a computer and if you enable a legacy boot option in the configuration file, rEFInd notifies you of its inability to present legacy boot options when it starts up. rEFInd's legacy boot support also depends on features that are not available in the GNU-EFI development package, so you may see a similar notice if you run a version of rEFInd compiled with that package. (The primary build available on the <a href="getting.html">Getting rEFInd</a> page is compiled with the TianoCore EDK2 package, which does support the BIOS boot features.)</p>
-<p>The <tt>scanfor</tt> option, described on the <a href="configfile.html">Configuring the Boot Manager</a> page, controls rEFInd's detection of legacy OSes. On Macs, the default is to scan for such OSes, since a common boot scenario on Macs is dual-booting OS X and Windows, and of course BIOS support is required for this. (rEFInd 0.4.5 and earlier did <i>not</i> scan for legacy OSes by default, though, so you may need to change this option if you're upgrading and don't want to scan for legacy OSes.) On UEFI PCs, rEFInd defaults to <i>not</i> scanning for legacy OSes; thus, you must edit the <tt>scanfor</tt> item in the configuration file if you want to boot a legacy OS on a UEFI PC.</p>
+<p>The <tt>scanfor</tt> option, described on the <a href="configfile.html">Configuring the Boot Manager</a> page, controls rEFInd's detection of legacy OSes. On Macs, the default is to scan for such OSes, since a common boot scenario on Macs is dual-booting OS X and Windows, and of course BIOS support is required for this. On UEFI PCs, rEFInd defaults to <i>not</i> scanning for legacy OSes; thus, you must edit the <tt>scanfor</tt> item in the configuration file if you want to boot a legacy OS on a UEFI PC.</p>
<img src="os_legacy.png" align="right" width="128" height="128"
alt="The legacy OS icon is identical for all OSes on UEFI-based PCs."
border=2 background="gray"/>
-<p>On Macs, rEFInd uses a flexible scanning algorithm inherited from rEFIt. This procedure detects most legacy OSes on most disks, although it can sometimes miss an OS. This scanning algorithm can often identify the legacy OS you've installed and present a suitable icon. On UEFI PCs, rEFInd relies on the computer's NVRAM settings to determine which legacy boot loaders to scan; if an OS isn't listed in the NVRAM settings, rEFInd won't present it as an option. On most UEFI PCs, at least one hard disk and your optical drive appear as options. The two computers I've tested have failed to present USB flash drives as boot options when inserted, though. You may be able to get additional options to appear by editing your boot list in your firmware's setup utility, but I can make no promises about this. The UEFI scanning procedure is also incapable of detecting the OS type, so you'll see a generic legacy OS icon, as shown at the right.</p>
+<p>On Macs, rEFInd uses a flexible scanning algorithm inherited from rEFIt. This procedure detects most legacy OSes on most disks, although it can sometimes miss an OS. This scanning algorithm can often identify the legacy OS you've installed and present a suitable icon. On UEFI PCs, rEFInd relies on the computer's NVRAM settings to determine which legacy boot loaders to scan, but rEFInd does tell the firmware to find every BIOS-mode boot option and add it to its NVRAM list. On most UEFI PCs, at least one hard disk and your optical drive appear as options. On one computer I tested (a Lenovo laptop), the internal hard disk appears in the rEFInd menu as a removable disk, and selecting any BIOS-mode option causes the computer to attempt a network boot. Three other computers I've tested behave more sensibly. If you opt to scan for BIOS-mode optical disks (<tt>scanfor cd</tt>) on UEFI-based PCs, an icon will appear whether or not your drive holds a CD. The UEFI scanning procedure is also incapable of detecting the OS type, so you'll see a generic legacy OS icon, as shown at the right.</p>
+
+<p>On both PCs and Macs, if you see non-functional legacy boot options, you can remove them by using the <tt>dont_scan_volumes</tt> token in <tt>refind.conf</tt>: Add any substring from the description that appears when you highlight the non-functional option to the set of options to have rEFInd ignore that entry. (Note that you must provide a complete volume name when excluding EFI volumes from scanning. The legacy-mode exclusion operation is more flexible in this regard.)</p>
+
+<a name="delays">
+<h2>Reducing Startup Delays</h2>
+</a>
+
+<p>You may discover that rEFInd takes a while to appear on the screen compared to other boot managers and boot loaders. Ultimately, the reason is that rEFInd is doing more—it's reading more filesystems, scanning for bootable files, and so on. In most cases, rEFInd takes just a second or two longer than other boot loaders, but I've heard of (and seen) much longer delays on computers that are configured sub-optimally. Some things you can do to reduce these delays include:</p>
+
+<ul>
+
+<li><b>Remove unnecessary drivers</b>—Simply loading a driver takes a certain amount of time, and if a filesystem driver finds a filesystem to read, rEFInd will spend time scanning that filesystem for bootable files. If there are no such files, or if you're not using them, then this is wasted time. Thus, you should check the <tt>drivers</tt>, <tt>drivers_x64</tt>, or other architecture-specific drivers subdirectory to be sure it doesn't hold unnecessary drivers.</li>
+
+<li><b>Use FAT for <tt>/boot</tt></b>—This tip is a corollary of the preceding one. If you use rEFInd to boot the Linux kernel directly, and if you rely on a driver to read the Linux kernel, then you'll have to live with the time to load the driver and to scan at least one extra filesystem. If you mount your ESP at <tt>/boot</tt>, or even if you create a separate FAT <tt>/boot</tt> partition, you'll save a little time. Note, however, that most Linux distributions don't allow you to install to a system with a FAT <tt>/boot</tt> partition, so you may need to set this up after doing your initial installation. If you see symbolic links in <tt>/boot</tt>, be wary; your distribution may rely upon them, and because FAT doesn't support symbolic links, this action may cause problems when upgrading kernels. On Macs, you can use HFS+ for this purpose, since Apple's EFI implementation includes an HFS+ driver.</li>
+
+<li><b>Minimize the number of scanned filesystems</b>—There's overhead associated with every additional filesystem rEFInd scans. Thus, if you have, say, separate ext4fs root (<tt>/</tt>), <tt>/boot</tt>, <tt>/usr</tt>, <tt>/home</tt>, and <tt>/var</tt> filesystems, and if you install rEFInd's ext4fs driver, rEFInd will end up scanning at least six filesystems (counting the FAT ESP), although only one of those has Linux kernels. You can use FAT for <tt>/boot</tt> and remove the ext4fs driver to speed up the boot process, as just described; but if you prefer to avoid the downsides of that action, you can switch <tt>/boot</tt> to some other filesystem, such as ext2fs or ReiserFS. This plan will reduce the number of filesystems to be scanned and improve boot time. Alternatively, if you re-install Linux, you can reduce the number of partitions or use LVM (which rEFInd can't read) for all of your filesystems except for <tt>/boot</tt>.</li>
+
+<li><b>Use a speedier filesystem</b>—In my tests, rEFInd's ReiserFS driver is the fastest and ext2fs is the slowest, with Btrfs and ext4fs falling in-between these two. The difference is trivial on some computers but it's noticeable on others. Filesystem speed differences are more likely to be noticeable in the time it takes to boot the OS; rEFInd's own startup time is less likely to be affected by a filesystem change.</li>
+
+<li><b>Use a speedier driver</b>—rEFInd 0.7.0 introduced a read-ahead cache in its filesystem drivers, which greatly improved their speed on some systems. If you're using an older driver, try using a newer one. Pete Batard's <a href="https://github.com/pbatard/efifs">efifs drivers</a> are an alternative to rEFInd's drivers. The efifs drivers are still very new and rapidly changing. My initial impression is that some of them are quite speedy, but others are very slow.</li>
+
+<li><b>Delete or move files and directories</b>—By default, rEFInd scans the root (<tt>/</tt>) directory, <tt>/boot</tt>, and most subdirectories of <tt>/EFI</tt> on every partition that it scans. If these locations exist but contain no bootable files, they'll just slow rEFInd down. Likewise, if you use <tt>dont_scan_files</tt> to keep unused boot loaders out of the menu, rEFInd will still do much of the work of scanning those files. In all of these cases, deleting or moving the directories or files that are being scanned but that don't contain bootable options you want to see can speed things up.</li>
+
+<li><b>Use the <tt>also_scan_dirs</tt> option sparingly</b>—Using <tt>also_scan_dirs</tt> is useful in some situations, but it does add to rEFInd's task list. Use it only if you must.</li>
+
+<li><b>Reduce the <tt>scanfor</tt> list</b>—Removing items from the <tt>scanfor</tt> list in <tt>refind.conf</tt> can speed things up a bit. This is especially true on Macs, which scan for BIOS-mode boot loaders by default. If you never boot a Mac in BIOS mode, try uncommending <tt>scanfor</tt> and ensure that the <tt>hdbios</tt>, <tt>biosexternal</tt>, and <tt>cd</tt> options are <i>not</i> present. The <tt>external</tt> and <tt>optical</tt> items won't add delays <i>unless</i> the relevant media are inserted, which brings us to....</li>
+
+<li><b>Don't boot with removable media attached (unless you intend to boot from them)</b>—If you insert an optical disc into your drive or plug in a removable device like a USB flash drive, rEFInd will attempt to scan it. This will slow down rEFInd's startup process, so you shouldn't make a habit of booting with such media inserted. In fact, there's another reason not to boot with external media attached: If such a medium is infected with malware, and if your firmware is configured to boot from external media first, you'll end up running the malware, possibly infecting your computer.</li>
+
+</ul>
+
+<p>I hope these tips will help you to overcome any speed problems you're experiencing. As I said, rEFInd is reasonably fast on many computers, so you might not run into problems in the first place. If you do, though, reducing rEFInd's workload can help.</p>
<hr />
-<p>copyright © 2012–2013 by Roderick W. Smith</p>
+<p>copyright © 2012–2014 by Roderick W. Smith</p>
<p>This document is licensed under the terms of the <a href="FDL-1.3.txt">GNU Free Documentation License (FDL), version 1.3.</a></p>