href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com</a></p>
<p>Originally written: 3/14/2012; last Web page update:
-8/12/2012, referencing rEFInd 0.4.5</p>
+10/6/2012, referencing rEFInd 0.4.6</p>
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<p class="sidebar"><b>Note:</b> rEFInd defaults to scanning for EFI, but <i>not</i> for BIOS, boot loaders. If you want to launch BIOS-mode OSes from rEFInd, you must edit the <tt>scanfor</tt> line in <tt>refind.conf</tt>, as described on the <a href="configfile.html">Configuring the Boot Manager</a> page. This type of configuration is most likely to be necessary on Macs that dual-boot with Windows.</p>
-<p>Ordinarily, rEFInd displays tags for OSes it finds on internal hard disks, external hard disks (including USB flash drives, CF disks, and so on), and optical discs. Sometimes, though, the firmware hasn't had time to fully examine these devices by the time rEFInd starts; or you might only insert or plug in the media after rEFInd appears. In these cases, you can press the Esc key to have rEFInd re-read its configuration file and re-scan your media for boot loaders. This action can take a few seconds to complete, so be patient. You can also use this feature to detect OSes if you launch a shell and use it to load a driver or edit the <tt>refind.conf</tt> file.</p>
+<p>Ordinarily, rEFInd displays tags for OSes it finds on internal hard disks, external hard disks (including USB flash drives, CF disks, and so on), and optical discs. Sometimes, though, the firmware hasn't had time to fully examine these devices by the time rEFInd starts; or you might only insert or plug in the media after rEFInd appears. In these cases, you can press the Esc key to have rEFInd re-read its configuration file and re-scan your media for boot loaders. This action can take a few seconds to complete, so be patient. You can also use this feature to detect OSes if you launch a shell and use it to load a driver or edit the <tt>refind.conf</tt> file. If you regularly need to press Esc, you might look into the <tt>scan_delay</tt> configuration file option, described on the <a href="configfile.html">Configuring the Boot Manager</a> page.</p>
<h2>Using Keyboard Shortcuts</h2>
<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">
+<h2>Booting Legacy OSes</h2>
+</a>
+
+<p>Sometimes it's necessary to boot a legacy (BIOS-based) OS on an EFI computer. This is especially true on Macs, since this is the usual method of dual-booting OS X and Windows. In fact, even most Linux distributions install more easily in BIOS mode on Macs, although running Linux in EFI mode has its advantages. (See my <a href="http://www.rodsbooks.com/ubuntu-efi/">EFI-Booting Ubuntu on a Mac</a> page for an in-depth look at this topic.)</p>
+
+<p>On UEFI-based PCs, booting some OSes in EFI mode and others in BIOS mode is less often necessary, since it's usually easy to install all your OSes in BIOS mode. If you have a working EFI-mode OS installation, though, and if you want to install an OS that lacks EFI-mode boot support, you may need to boot in both modes. This may happen if you want to add one of the BSDs (FreeBSD, OpenBSD, NetBSD, and so on) to a working system, for instance. You might also want to boot a BIOS-mode emergency recovery CD, such as <a href="http://partedmagic.com">Parted Magic</a> or <a href="http://www.sysresccd.org">System Rescue CD.</a></p>
+
+<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>
+
+ <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>
+
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<p>copyright © 2012 by Roderick W. Smith</p>