The BootMaintenanceManagerUiLib use ChooseFile() from FileExplorerLib to select files. And the third parameter in ChooseFile() is CHOOSE_HANDLER, per the definition of CHOOSE_HANDLER, it must use EFIAPI as the calling convention. But the calling convention was not specified for following handlers: CreateBootOptionFromFile, CreateDriverOptionFromFile, BootFromFile. Now specifies the calling convention for those functions. Cc: Liming Gao <liming.gao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Dandan Bi <dandan.bi@intel.com> Reviewed-by: Eric Dong <eric.dong@intel.com> Reviewed-by: Gary Lin <glin@suse.com>