Create UEFI boot USB

This article explains how to create an UEFI boot USB with parted and gummiboot.

In this example we will use /dev/sdX. This will be different depending on your system.

Create GPT boot partition

Install parted

apk add parted

Create a single UEFI boot partitions.

Warning: this will erase all content of your /dev/sdX. Make sure that you use correct device

parted --script /dev/sdX mklabel gpt

parted --script --align=optimal /dev/sdX mkpart ESP fat32 1MiB 512MiB

parted --script /dev/sdX set 1 boot on

Create fat32 filesystem

Create a fat32 system with the name `Alpine`.

mkfs.vfat -n Alpine /dev/sdX1

Copy content of ISO image to filesystem

It is possible to mount the iso image and copy files with cp or rsync and it is also possible to use 7z to extract content from the iso. In this example I will use the uniso utility from alpine-conf package.

mount -t vfat /dev/sdX1 /mnt

cd /mnt && uniso < /path/to/alpine-3.4.0-x86_64.iso

Copy gummiboot efi binary

UEFI will look for a EFI/bootx64.efi as a fallback efi loader. We copy gummibootx64.efi to this location.

mkdir -p /mnt/EFI/Boot

apk add gummiboot

cp /usr/lib/gummiboot/gummibootx64.efi /mnt/EFI/Boot/bootx64.efi

Create configuration files for boot loader

We need create some configuration files for gummiboot.

mkdir -p loader/entries

Contents of loader/loader.conf

default grsec
timeout 4

The options are taken from boot/syslinux/syslinux.cfg

Contents of loader/entries/grsec.conf

title    Alpine Linux
linux    /boot/vmlinuz-grsec
initrd   /boot/initramfs-grsec
options  modloop=/boot/modloop-grsec modules=loop,squashfs,sd-mod,usb-storage quiet

Finally umount the disk

cd ~ && umount /mnt