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+<!DOCTYPE html>
+<html>
+<head>
+ <meta charset="utf-8">
+ <meta name="viewport" content="width=device-width, initial-scale=1">
+
+ <style type="text/css">
+ @import url('../css/main.css');
+ </style>
+
+ <title>Writing a GRUB configuration file</title>
+</head>
+
+<body>
+ <div class="section">
+ <h1 id="pagetop">Writing a GRUB configuration file</h1>
+
+ <p>
+ <a href="index.html">Back to index</a>
+ </p>
+ </div>
+
+ <div class="section">
+
+ <h1>Table of Contents</h1>
+
+ <li>
+ <a href="#example_modifications">Example modifications for <i>grubtest.cfg</i></a>
+ <ul>
+ <li><a href="#example_modifications_trisquel">Trisquel GNU/Linux-libre</a></li>
+ <li><a href="#example_modifications_parabola">Parabola GNU/Linux-libre</a></li>
+ </ul>
+ </li>
+
+ </div>
+
+ <div class="section">
+ <h2 id="example_modifications">Example modifications for <i>grubtest.cfg</i></h2>
+
+ <p>
+ These are some common examples of ways in which the grubtest.cfg file can be modified.
+ </p>
+
+
+ <div class="subsection">
+ <h3 id="example_modifications_trisquel">Trisquel GNU/Linux-libre</h3>
+
+ <p>
+ As an example, on my test system in /boot/grub/grub.cfg (on the HDD/SSD) I see for the main menu entry:
+ </p>
+ <ul>
+ <li><b>linux /boot/vmlinuz-3.15.1-gnu.nonpae root=UUID=3a008e14-4871-497b-95e5-fb180f277951 ro crashkernel=384M-2G:64M,2G-:128M quiet splash $vt_handoff</b></li>
+ <li><b>initrd /boot/initrd.img-3.15.1-gnu.nonpae</b></li>
+ </ul>
+
+ <p>
+ <b>ro</b>, <b>quiet</b>, <b>splash</b>, <b>crashkernel=384M-2G:64M,2G-:128M</b> and
+ <b>$vt_handoff</b> can be safely ignored.
+ </p>
+
+ <p>
+ I use this to get my partition layout:<br/>
+ $ <b>lsblk</b>
+ </p>
+
+ <p>
+ In my case, I have no /boot partition, instead /boot is on the same partition as / on sda1.
+ Yours might be different. In GRUB terms, sda means ahci0. 1 means msdos1, or gpt1, depending
+ on whether I am using MBR or GPT partitioning. Thus, /dev/sda1 is GRUB is (ahci0,msdos1) or
+ (ahci0,gpt1). In my case, I use MBR partitioning so it's (ahci0,msdos1).
+ 'msdos' is a GRUB name simply because this partitioning type is traditionally used by MS-DOS.
+ It doesn't mean that you have a proprietary OS.
+ </p>
+
+ <p>
+ Trisquel doesn't keep the filenames of kernels consistent, instead it keeps old kernels and
+ new kernel updates are provided with the version in the filename. This can make GRUB payload
+ a bit tricky. Fortunately, there are symlinks /vmlinuz and /initrd.img
+ so if your /boot and / are on the same partition, you can set GRUB to boot from that.
+ These are also updated automatically when installing kernel updates from your distributions
+ apt-get repositories.
+ <b>
+ Note: when using <a href="http://jxself.org/linux-libre">jxself kernel releases</a>,
+ these are not updated at all and you have to update them manually.
+ </b>
+ </p>
+
+ <p>
+ For the GRUB payload grubtest.cfg (in the 'Load Operating System' menu entry), we therefore have (in this example):<br/>
+ <b>set root='ahci0,msdos1'</b><br/>
+ <b>linux /vmlinuz root=UUID=3a008e14-4871-497b-95e5-fb180f277951</b><br/>
+ <b>initrd /initrd.img</b>
+ </p>
+
+ <p>
+ Optionally, you can convert the UUID to its real device name, for example /dev/sda1 in this case.
+ sdX naming isn't very reliable, though, which is why UUID is used for most distributions.
+ </p>
+
+ <p>
+ Alternatively, if your /boot is on a separate partition then you cannot rely on the /vmlinuz and /initrd.img symlinks.
+ Instead, go into /boot and create your own symlinks (update them manually when you install a new kernel update).<br/>
+ $ <b>sudo -s</b><br/>
+ # <b>cd /boot/</b><br/>
+ # <b>rm -Rf vmlinuz initrd.img</b><br/>
+ # <b>ln -s <u>kernel</u> ksym</b><br/>
+ # <b>ln -s <u>initrd</u> isym</b><br/>
+ # <b>exit</b>
+ </p>
+
+ <p>
+ Replace the underlined <b>kernel</b> and <b>initrd</b> filenames above with the actual filenames, of course.
+ </p>
+
+ <p>
+ Then your grubtest.cfg menu entry (for payload) becomes like that, for example if / was on sda2 and /boot was on sda1:<br/>
+ <b>set root='ahci0,msdos1'</b><br/>
+ <b>linux /ksym root=/dev/sda2</b><br/>
+ <b>initrd /isym</b>
+ </p>
+
+ <p>
+ There are lots of possible variations so please try to adapt.
+ </p>
+
+ </div>
+
+ <div class="subsection">
+ <h3 id="example_modifications_parabola">Parabola GNU/Linux-libre</h3>
+
+ <p>
+ You can basically adapt the above. Note however that Parabola does not keep old kernels still installed, and the file names
+ are always consistent, so you don't need to boot from symlinks, you can just use the real thing directly.
+ </p>
+ </div>
+
+ <p>
+ <a href="#pagetop">Back to top of page.</a>
+ </p>
+
+ </div>
+
+ <div class="section">
+
+ <p>
+ Copyright &copy; 2014, 2015 Francis Rowe &lt;info@gluglug.org.uk&gt;<br/>
+ This document is released under the Creative Commons Attribution-ShareAlike 4.0 International Public License and all future versions.
+ A copy of the license can be found at <a href="../cc-by-sa-4.txt">../cc-by-sa-4.txt</a>.
+ </p>
+
+ <p>
+ This document is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See <a href="../cc-by-sa-4.txt">../cc-by-sa-4.txt</a> for more information.
+ </p>
+
+ </div>
+
+</body>
+</html>