/boot/extlinux.conf

DEFAULT menu.c32
PROMPT 0
MENU TITLE Alpine/Linux Boot Menu
MENU HIDDEN
MENU AUTOBOOT Alpine will be booted automatically in # seconds
TIMEOUT 30
LABEL virt
  MENU LABEL linux virt
  LINUX vmlinuz-virt
  INITRD initramfs-virt
  APPEND root=UUID=59c56381-e5ec-4a8b-8c2e-f9c6a66d524c moudles=sd-mod,usb-storage,ext4 quiet rootfstype=ext4

MENU SEPARATOR