Simple UEFI boot loader which executes configured EFI images, where the
default entry is selected by a configured pattern (glob) or an on-screen
menu.

Operates on the EFI System Partition (ESP) only. Configuration file fragments,
kernels, initrds, other EFI images need to reside on the ESP. Linux kernels
need to be built with CONFIG_EFI_STUB to be able to be directly executed as
an EFI image.

Reads simple and entirely generic boot loader configurion files; one
file per boot loader entry to select from.

Pressing the space (or most other) keys during bootup will show
an on-screen menu with all configured loader entries to select from.
Pressing enter on the selected entry loads and starts the EFI image.

If no timeout is configured and no key pressed during bootup, the default
entry is booted right away.

The config files should be named like:
  (ESP)/loader/entries/<vendor>-<release>.conf

  $ cat /boot/loader/entries/fedora-3.5.4-1.fc18.x86_64.conf
  title   Fedora 18 (3.5.4-1.fc17.x86_64)
  linux   /fedora/vmlinuz-3.5.4-1.fc17.x86_64
  initrd  /fedora/initrd-3.5.4-1.fc17.x86_64
  options root=UUID=f8f83f73-df71-445c-87f7-31f70263b83b

  $ cat /boot/loader/entries/custom-kernel.conf
  title   My test Kernel - without initramfs
  options root=PARTUUID=084917b7-8be2-4e86-838d-f771a9902e08
  linux   /bzImage

  $ cat /boot/loader/entries/redhat-grub.conf
  title   GRUB
  efi     /EFI/redhat/grub2-efi/grub.efi

  $ cat /boot/loader/entries/zzz-efi-shell.conf
  title   EFI Shell
  efi     /EFI/shell/Shell.efi

Paths are automatically converted from '/' to '\', and a leading '\' is
added if needed.

Loader options can be stored in:
  (ESP)/loader/loader.conf

  $ cat /boot/loader/loader.conf
  timeout 10
  default fedora-*

The timeout is specified in seconds, the default is 0, which suppresses the
menu. If a timeout is given, in the config file or in the EFI variable
"LoaderConfigTimeout", the on-screen menu with the default entry selected is
shown, and a timer counting downwards.

Pressing the '+' or '-' key in the menu will set or clear a custom timeout
value. The setting is stored persistently in the EFI variable "LoaderConfigTimeout".

The default entry is selected by a pattern match on the configuration file
names. The matched strings are basenames of the config files translated to
lowercase and without the ".conf" suffix. The last matching entry in the
sorted list is selected. If no match pattern is specified, the last entry in
the list is selected.

This will automatically select the latest Fedora kernel entry:
   default fedora-*

This will automatically select the latest Fedora 18 kernel:
   default fedora-*.fc18.*

Pressing the 'd' key in the menu will mark the selected entry as the default
boot entry. The entry is identified by a leading '*'. Pressing the 'd' key again
will clear the setting. The setting is stored persistently in the EFI variable
"LoaderConfigDefault".

Pressing 'o' allows to edit the options for this bootup.

Pressing 'v' shows the loader and EFI version numbers.

Pressing 'F1' will show the available keys.

The EFI variable LoaderEntryOneShot= can be used to specify a loader entry
for the next and only the next reboot. The variable will always be cleared
directly after it is read.

Before executing the selected image, the boot entry indentifier is stored in
the EFI variable "LoaderEntrySelected" and available during runtime at:
  /sys/firmware/efi/vars/LoaderEntrySelected-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f/

The allocated random UUID 4a67b082-0a4c-41cf-b6c7-440b29bb8c4f is meant to be
shared across tools which implement the config file layout, format, and the EFI
variables.