Add a new 'initrd' command to the UEFI Shell that allows any file that is accessible to the shell to be registered as the initrd that is returned when Linux's EFI stub loader invokes the LoadFile2 protocol on its special vendor media device path. Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2564 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Laszlo Ersek <lersek@redhat.com>