<p>Haiku's Boot Loader can help when you experience hardware related problems or want to choose which Haiku installation to start, if you have more than one (maybe on an installation CD or USB stick). It's also handy if you have installed a software component that acts up and prevents you from booting Haiku, see <ahref="#troubleshooting">Troubleshooting</a> below.</p>
<p>To enter the Boot Loader options, you have to press and keep holding the <spanclass="key">SHIFT</span> key before the beginning of Haiku's boot process. If there's a boot manager installed, you can start holding <spanclass="key">SHIFT</span> before invoking the boot entry for Haiku. If Haiku is the only operating system on the machine, you can begin holding the key while still seeing boot messages from the BIOS.</p>
<tr><td><b>Select safe mode options</b></td><td></td><td>There are several options to try in case of hardware related trouble or if the system becomes unstable or unbootable because of a misbehaving add-on. When moving the selection bar to an option, a short explanation appears at the bottom of the screen.</td></tr>
<tr><td></td><td></td><td>
<p><spanclass="menu">Safe mode</span><br/>
Puts the system into safe mode. This can be enabled independently from the other options.</p>
<p><spanclass="menu">Disable user add-ons</span><br/>
Prevents all user installed add-ons from being loaded. Only the add-ons in the system directory will be used. See <ahref="#troubleshooting">Troubleshooting</a> below.</p>
<p><spanclass="menu">Disable IDE DMA</span><br/>
Disables IDE DMA, increasing IDE compatibility at the expense of performance.</p>
Allows to select system files that shall be ignored. Useful e.g. to disable drivers temporarily. See <ahref="#troubleshooting">Troubleshooting</a> below.</p></td></tr>
<tr><td><b>Select debug options</b></td><td></td><td>Here you'll find several options that help with debugging or getting details for a <ahref="../welcome/en/bugreports.html">bug report</a>. Again, a short explanation for each option is displayed at the bottom.</td></tr>
<tr><td></td><td></td><td>
<p><spanclass="menu">Enable serial debug output</span><br/>
Turns on forwarding the syslog output to the serial interface (default: 115200, 8N1).</p>
<p><spanclass="menu">Enable on screen debug output</span><br/>
Display debug output on screen while the system is booting, instead of the normal boot logo.</p>
<p><spanclass="menu">Disable on screen paging</span><br/>
Disables paging when on screen debug output is enabled.</p>
Allows advanced debugging options to be entered directly.</p></td></tr>
<tr><td></td><td></td><td>If "<i>Enable debug syslog</i>" is activated, a warm reboot after a crash shows these additional options:</td></tr>
<tr><td></td><td></td><td><p><spanclass="menu">Save syslog from previous session during boot</span><br/>
Saves the syslog from the previous Haiku session to /var/log/previous_syslog when booting.</p>
<p><spanclass="menu">Display syslog from previous session</span><br/>
Displays the syslog from the previous Haiku session</p>
<p><spanclass="menu">Save syslog from previous session</span><br/>
Saves the syslog from the previous Haiku session to disk. Currently only FAT32 volumes are supported.</p></td></tr>
<tr><tdclass="onelinetop"><b>Select fail safe video mode</b></td><td></td><td>If you had to activate the option <i>Use fail-safe video mode</i>, you can set resolution and color depth.</td></tr>
<p>If Haiku refuses to boot on your hardware from the get-go, try out setting different options under <spanclass="menu">Select safe mode options</span>. Consider filing a <ahref="../welcome/en/bugreports.html">bug report</a> in any case.</p>
<p>On the other hand, if Haiku only suddenly acts up after you have installed some software, especially hardware drivers, you have several options to get Haiku bootable again so you can uninstall the offending package:</p>
<li><p>Activating <spanclass="menu">Safe mode</span> will prevent most servers, daemons and the UserBootScript from being started.</p></li>
<li><p>Activating <spanclass="menu">Disable user add-ons</span> will prevent using any add-ons (drivers, translators, etc.) you have installed in the user hierarchy under your Home folder.</p></li>
<li><p>If the offending driver, add-on etc. is installed in the system hierarchy, things get a bit more complicated, because that area is read-only. Here, the <spanclass="menu">Blacklist entries</span> comes into play. With it, you can navigate through the whole system hierarchy and disable the component that's messing things up for you by checking an entry with the <spanclass="key">SPACE</span> or <spanclass="key">RETURN</span> key. <spanclass="key">ESC</span> returns you up one level to the parent directory.</p>
<p>Online, there's the article <ahref="http://www.haiku-os.org/blog/barrett/2013-12-15_how_permanently_blacklist_package_file">How to Permanently Blacklist a Package File</a> showing how to make that setting stick.</p></li>
<li><p>Under <spanclass="menu">Select boot volume</span> you can specify what former "version" of Haiku to boot. Every time you un/install a package, the old state is saved and you can boot into it by choosing it from the list presented in the boot loader options.<br/>
So, if you encounter boot problems after installing some package, boot a Haiku version from before that time and uninstall the offending package.</p></li>
