Dualbooting

Warning: This Dualboot manual is intended for experienced users. You will have to figure out your bootloader and manually edit partitions on your disk. A script to make installation of Alpine to a free space on a disk alongside another operating system as simple and straightforward as to a full disk with setup-alpine is yet to be written. If you doubt you can do it, it may be better for you to buy an external drive, use a VM for a second OS or choose another distro.

It's assumed you have a box where you already run another operating system, and would like to be able to dual boot either the installed system or Alpine Linux.

Note: If you are interested in installing Alpine Linux in a virtual machine/containers refer virtualization and Category:Virtualization.

Basic setup

Follow the Installation steps until the Base configuration. i.e set up Alpine without installing to a disk.

Create a Partition

To dual boot, Alpine needs a separate partition where it can be installed to. If you don't already have one free, refer Manual partitioning, to create a new Partition.

Make note of what partition you will use for your Alpine installation. In this example we are going to install Alpine on /dev/sdXY.

Note: If you are using btrfs filesystem, there is no need to create a partition. Refer btrfs tutorial

.

Format the partition

First format your partition. The above Setting_up_disks_manually#Manual_partitioning would have installed the necessary tool. If not, install the necessary tools for doing the formatting.

Warning: Make sure you format the right partition! The /dev/sdXY is only a example. If you choose the wrong partition, your data will be gone. Make a backup first if you are unsure.

# apk add e2fsprogs

# mkfs.ext4 /dev/sdXY

Mount the partition

Mount the newly formatted partition. After mounting, the partition will be available at /mnt.

# mount -t ext4 /dev/sdXY /mnt

Install Alpine

Now it's time to copy the prepared system to the prepared partition(s) that were mounted below /mnt.

# setup-disk -m sys /mnt

See setup-disk for more details.

Tip: If you use extlinux (default) and didn't create a separate boot partition, (/boot resides on the root partition /).

You might need to adjust the paths to the boot files in /boot/extlinux.conf, eg.:

[...]
LABEL hardened
  MENU DEFAULT
  MENU LABEL Linux hardened
  LINUX /boot/vmlinuz-lts
  INITRD /boot/initramfs-lts
[...]

Check that the LINUX and INITRD paths actually point to the files shipped in your Alpine Linux release.

Configure bootloader

There are different ways to get a boot menu that allows selecting the operating system to boot.

It is easiest on (U)EFI based hardware platforms, where one may simply install the rEFInd boot menu, as explained in Bootloaders.

Otherwise, one may adjust the bootloader that has already been installed (by the other operating system). Because bootloaders vary, you'll need to figure out how to make yours boot your Alpine install.

Hopefully you can get some ideas from the following example, adjusting Grub2 to boot Alpine:

Reboot your system (start Ubuntu).

Start a 'terminal' (ALT-F2 + "terminal" + [Run])

Take notes of the UUID of the partition you are planning to use:

# blkid /dev/sdXY

Start editing the grub2 configuration

# gedit /etc/grub.d/40_custom

I edited the file to look something like this:

Contents of /etc/grub.d/40_custom

#!/bin/sh echo "Adding Alpine" >&2 cat << EOF menuentry "Alpine Linux" { set root=(hd0,3) linux /boot/vmlinuz-lts root=UUID=8de6973a-4a8c-40ed-b710-c4e2b42d6b7a modules=sd-mod,usb-storage,ext4 quiet initrd /boot/initramfs-lts } EOF

Note: The root, linux, initrd, and UUID values mentioned above should be replaced with those of your system, e.g. the UUID you got when running the 'blkid' command.

Finally the configuration changes need to be applied to the grub2 bootloader:

update-grub

Now it's time to test. Reboot your box.

Note: You might need to press SHIFT when booting your box in order to see the grub-menu.

Windows

For Windows partitions to be detected with grub, you need `os-prober` and `grub-mount` installed at the time grub-mkconfig runs.

Note: The following needs to be tested

To upgrade the grub installation, the efi directory must be mounted in /boot/efi/. To know in which partition the efi is, we must examine the partition table, so if your main disk is /dev/sda then.

# fdisk -l /dev/sda

Device             Start        End   Sectors   Size Type
/dev/sda1           2048     309247    307200   150M EFI System

# mkdir /boot/efi

# mount /dev/sda1 /boot/efi/

# apk add efibootmgr

(If your system supports UEFI. Most PC's from 2010, support UEFI)

Install grub

# grub-install –root-directory=/mnt

After grub re-installation, unmount efi partition:

# umount /boot/efi/

References

• Dual Boot Windows 11 and Alpine Linux
• Mount EFI
• Dual boot on a btrfs filesystem