I boot from a USB boot drive using UEFI. Because of the UEFI boot, it just a matter of copying the files from the alpine ISO to a USB thumbdrive VFAT32 partition. Partition may be set to EFI (but this doesn’t seem to be required).

Since I would like to switch between different alpine versions, I wrote a script to let me have multiple alpine versions and switch between them. The boot partition can be kept ro as the script will automatically remount rw.

In your boot/EFI partition, you need to have these two scripts:

The select.sh script is the main script. fixup.sh is called from select.sh to tweak the boot command line parameters. I use it to add dom0_mem=2048M arguments to the boot command line so that xen reserves memory for guests.

Usage:

Install an ISO image

Download a iso image from the alpine repository and enter:

sh select.sh --install <iso-file>

This will extract the contents of the <iso-file> and use fixup.sh to apply any necessary tweaks. The new ISO file will be placed in a directory named according to the alpine version.

Enabling a version

sh select.sh <directory>

Makes the alpine version in <directory> the current active version for boot.