From 8507c6adf8a3af268b8a7493339be253abb35c71 Mon Sep 17 00:00:00 2001 From: Francis Rowe Date: Mon, 08 Jun 2015 20:52:46 -0400 Subject: docs/gnulinux/grub_cbfs.html: split GRUB config guides to new doc --- (limited to 'docs/gnulinux/grub_config.html') diff --git a/docs/gnulinux/grub_config.html b/docs/gnulinux/grub_config.html new file mode 100644 index 0000000..2891ebc --- /dev/null +++ b/docs/gnulinux/grub_config.html @@ -0,0 +1,160 @@ + + + + + + + + + Writing a GRUB configuration file + + + +
+

Writing a GRUB configuration file

+ +

+ Back to index +

+
+ +
+ +

Table of Contents

+ +
  • + Example modifications for grubtest.cfg + +
    • + +
    + +
    +

    Example modifications for grubtest.cfg

    + +

    + These are some common examples of ways in which the grubtest.cfg file can be modified. +

    + + +
    +

    Trisquel GNU/Linux-libre

    + +

    + As an example, on my test system in /boot/grub/grub.cfg (on the HDD/SSD) I see for the main menu entry: +

    +
      +
    • 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
      • +
    • initrd /boot/initrd.img-3.15.1-gnu.nonpae
      • +
    + +

    + ro, quiet, splash, crashkernel=384M-2G:64M,2G-:128M and + $vt_handoff can be safely ignored. +

    + +

    + I use this to get my partition layout:
    + $ lsblk +

    + +

    + 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. +

    + +

    + 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. + + Note: when using jxself kernel releases, + these are not updated at all and you have to update them manually. + +

    + +

    + For the GRUB payload grubtest.cfg (in the 'Load Operating System' menu entry), we therefore have (in this example):
    + set root='ahci0,msdos1'
    + linux /vmlinuz root=UUID=3a008e14-4871-497b-95e5-fb180f277951
    + initrd /initrd.img +

    + +

    + 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. +

    + +

    + 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).
    + $ sudo -s
    + # cd /boot/
    + # rm -Rf vmlinuz initrd.img
    + # ln -s kernel ksym
    + # ln -s initrd isym
    + # exit +

    + +

    + Replace the underlined kernel and initrd filenames above with the actual filenames, of course. +

    + +

    + Then your grubtest.cfg menu entry (for payload) becomes like that, for example if / was on sda2 and /boot was on sda1:
    + set root='ahci0,msdos1'
    + linux /ksym root=/dev/sda2
    + initrd /isym +

    + +

    + There are lots of possible variations so please try to adapt. +

    + +
    + +
    +

    Parabola GNU/Linux-libre

    + +

    + 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. +

    +
    + +

    + Back to top of page. +

    + +
    + +
    + +

    + Copyright © 2014, 2015 Francis Rowe <info@gluglug.org.uk>
    + 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 ../cc-by-sa-4.txt. +

    + +

    + 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 ../cc-by-sa-4.txt for more information. +

    + +
    + + + -- cgit v0.9.1