public static function get_default_mode_stores() {
        global $OUTPUT;
        $instance = cache_config::instance();
        $adequatestores = cache_helper::get_stores_suitable_for_mode_default();
        $icon = new pix_icon('i/warning', new lang_string('inadequatestoreformapping', 'cache'));
        $storenames = array();
        foreach ($instance->get_all_stores() as $key => $store) {
            if (!empty($store['default'])) {
                $storenames[$key] = new lang_string('store_'.$key, 'cache');
            }
        }
        $modemappings = array(
            cache_store::MODE_APPLICATION => array(),
            cache_store::MODE_SESSION => array(),
            cache_store::MODE_REQUEST => array(),
        );
        foreach ($instance->get_mode_mappings() as $mapping) {
            $mode = $mapping['mode'];
            if (!array_key_exists($mode, $modemappings)) {
                debugging('Unknown mode in cache store mode mappings', DEBUG_DEVELOPER);
                continue;
            }
            if (array_key_exists($mapping['store'], $storenames)) {
                $modemappings[$mode][$mapping['store']] = $storenames[$mapping['store']];
            } else {
                $modemappings[$mode][$mapping['store']] = $mapping['store'];
            }
            if (!array_key_exists($mapping['store'], $adequatestores)) {
                $modemappings[$mode][$mapping['store']] = $modemappings[$mode][$mapping['store']].' '.$OUTPUT->render($icon);
            }
        }
        return $modemappings;
    }