Bootloaders

2017-12-20T06:37:47Z

Takitus: /* Installing Syslinux */ Spelling fix.

By default Alpine uses Syslinux as bootloader.
This page shows the basic steps you need to perform, if you for any reason want to switch bootloaders or apply some manual configuration.

= Installing Syslinux =

If you want to switch from another bootloader back to Syslinux, or if you for some reason want to install Syslinux manually, the following steps are required.

Install the <code>syslinux</code> package:

<pre>apk add syslinux</pre>

If you're using GPT partitions, install the GPT MBR onto the drive you want to install the bootloader on (in this case <code>/dev/sda</code>):

<pre>dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/gptmbr.bin of=/dev/sda</pre>

Or if you're using DOS partitions, install the DOS MBR instead:

<pre>dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/mbr.bin of=/dev/sda</pre>



Next install the required Syslinux binaries. Despite being called <code>extlinux</code>, Syslinux supports booting from FAT12/16/32, NTFS, ext2/3/4, Btrfs, XFS, and UFS/FFS filesystems.

<pre>extlinux --install /boot</pre>

The configuration file is located in <code>/boot/extlinux.conf</code>.
Alpine ships with a script called <code>update-extlinux</code> which automatically (re)generates this file, for example on updates to Syslinux.
The settings for this script can be found in <code>/etc/update-extlinux.conf</code>, including the option to disable automatic overwriting of <code>/boot/extlinux.conf</code>.
You can also place additional menu entries in the <code>/etc/update-extlinux.d/</code> directory, e.g. for dual booting.

== EFI ==

{{Todo|Work in progress. This should at least get you started.}}

Assuming <code>/mnt</code> is a FAT32 partition of type EF00 and <code>/boot</code> belongs to the rootfs created after running <code>setup-disk</code>:

<pre>
mkdir -p /mnt/EFI/syslinux
cp /usr/share/syslinux/efi64/* /mnt/EFI/syslinux/
cp /boot/extlinux.conf /mnt/EFI/syslinux/syslinux.cfg
cp /boot/vmlinuz* /mnt/
cp /boot/initramfs* /mnt/
</pre>

You may need to modify <code>/mnt/EFI/syslinux/syslinux.cfg</code> to change the paths to absolute paths (just add a / in front of the vmlinuz/initramfs entries),
or copy the files to <code>/mnt/EFI/syslinux</code> instead (XXX: untested).

= Installing GRUB =

To install GRUB in BIOS mode, (optionally) remove the Syslinux package and install the required GRUB packages:

<pre>apk del syslinux
apk add grub grub-bios</pre>

Next install the MBR and GRUB binaries to disk:

<pre>grub-install /dev/vda</pre>

GRUB ships with an automatic config generator, including some automatic detection of other operating systems installed on the device:

<pre>grub-mkconfig -o /boot/grub/grub.cfg</pre>

This script can be configured via the <code>/etc/default/grub</code> file.
See [https://www.gnu.org/software/grub/manual/html_node/Simple-configuration.html] for a list of available options.

[[Category:Installation]] [[Category:Booting]]

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Bootloaders