href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com</a></p>
<p>Originally written: 3/14/2012; last Web page update:
-3/1/2015, referencing rEFInd 0.8.7</p>
+9/19/2015, referencing rEFInd 0.9.2</p>
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<li class="tight"><a href="#submenu">Creating Submenu Entries</a></li>
+<li class="tight"><a href="#default">Adjusting the Default Boot Option</a></li>
+
</ul>
</div>
<tr>
<td><tt>scan_all_linux_kernels</tt></td>
<td>none or one of <tt>true</tt>, <tt>on</tt>, <tt>1</tt>, <tt>false</tt>, <tt>off</tt>, or <tt>0</tt></td>
- <td>When uncommented or set to <tt>true</tt>, <tt>on</tt>, or <tt>1</tt>, causes rEFInd to add Linux kernels (files with names that begin with <tt>vmlinuz</tt> or <tt>bzImage</tt>) to the list of EFI boot loaders, even if they lack <tt>.efi</tt> filename extensions. This simplifies use of rEFInd on most Linux distributions, which usually provide kernels with EFI stub loader support but don't give those kernels names that end in <tt>.efi</tt>. Of course, the kernels must still be stored on a filesystem that rEFInd can read, and in a directory that it scans. (<a href="drivers.html">Drivers</a> and the <tt>also_scan_dirs</tt> options can help with those issues.) As of version 0.5.0, this option is enabled in the default configuration file. The program default remains to not scan for such kernels, though, so you can delete or uncomment this option to keep them from appearing in your boot menu. Passing <tt>false</tt>, <tt>off</tt>, or <tt>0</tt> causes these kernels to not be scanned. (This could be useful if you want to override a setting of <tt>scan_all_linux_kernels</tt> in an included secondary configuration file.)</td>
+ <td>When uncommented or set to <tt>true</tt>, <tt>on</tt>, or <tt>1</tt>, causes rEFInd to add Linux kernels (files with names that begin with <tt>vmlinuz</tt> or <tt>bzImage</tt>) to the list of EFI boot loaders, even if they lack <tt>.efi</tt> filename extensions. This simplifies use of rEFInd on most Linux distributions, which usually provide kernels with EFI stub loader support but don't give those kernels names that end in <tt>.efi</tt>. Of course, the kernels must still be stored on a filesystem that rEFInd can read, and in a directory that it scans. (<a href="drivers.html">Drivers</a> and the <tt>also_scan_dirs</tt> options can help with those issues.) As of version 0.8.3, this option is enabled by default; to disable this feature, you must uncomment this token and set it to <tt>false</tt> or one of its synonyms (<tt>off</tt> or <tt>0</tt>).</td>
+</tr>
+<tr>
+ <td><tt>fold_linux_kernels</tt></td>
+ <td>none or one of <tt>true</tt>, <tt>on</tt>, <tt>1</tt>, <tt>false</tt>, <tt>off</tt>, or <tt>0</tt></td>
+ <td>When uncommented or set to <tt>true</tt>, <tt>on</tt>, or <tt>1</tt>, causes rEFInd to "fold" all Linux kernels in a given directory into a single main-menu icon. Selecting that icon launches the most recent kernel. To launch an older kernel, you must press F2 or Insert; older kernels appear on the resulting submenu display. (You can type, as <tt>root</tt>, <tt class="userinput">touch /boot/vmlinuz-{whatever}</tt>, to make <tt>/boot/vmlinuz-{whatever}</tt> your default kernel in a directory.) If you prefer to see all your kernels in the main menu, set this option to <tt>false</tt>, <tt>off</tt>, or <tt>0</tt>. Note that this option is new with version 0.9.0, which changes the default behavior; earlier versions of rEFInd behaved as if <tt>fold_linux_kernels false</tt> was set.</td>
</tr>
<tr>
<td><tt>max_tags</tt></td>
</ul>
+<a name="default">
+<h2>Adjusting the Default Boot Option</h2>
+</a>
+
+<p>Just before launching an OS, rEFInd stores the description in the EFI variable <tt>PreviousBoot</tt> with a GUID of 36d08fa7-cf0b-42f5-8f14-68df73ed3740. The next time it launches, it reads that same variable and sets the default boot loader to that value, if it's still available and if the first item in <tt>default_selection</tt> in the <tt>refind.conf</tt> file is a plus sign (<tt>+</tt>).</p>
+
+<p>Under Linux, the variable that rEFInd uses to store this information is accessible as <tt>/sys/firmware/efi/efivars/PreviousBoot-36d08fa7-cf0b-42f5-8f14-68df73ed3740</tt>. Thus, you can back up this value, modify it, and write it back out to adjust your next-booted OS. Getting this string just right can be a bit tricky, though, and if the kernel doesn't like its format, it will not let you modify the variable. If you try to modify the variable, be aware that it's stored in UTF-16 format. As with the <tt>default_selection</tt> token in <tt>refind.conf</tt>, you can enter any substring that uniquely identifies the entry you want to boot.</p>
+
+<p>In principle, you should be able to use a similar procedure to force rEFInd to boot another OS by default in any other OS that supports writing EFI runtime variables. Unfortunately, I don't know the mechanisms used for this task in Windows, OS X, FreeBSD, or any other OS.</p>
+
+<p>If you want to consistently boot a particular OS by default and ignore the previous boot, you can use <tt>default_selection</tt>, but <i>omit</i> the <tt>+</tt> at the start of the line.</p>
+
+<p></p>
+
+<p></p>
+
+<p></p>
+
<hr />
<p>copyright © 2012–2015 by Roderick W. Smith</p>