index.php
The first page hit is the Index.php
This file calls Mage::run()
app/mage.php
The Mage::run() function then calls Mage_Core_Model_App->run()
app/code/mage/core/Model/App.php
The run function then calls $this->baseInit($options)
The baseInit function then calls $this->_initModules();
$this->_config->loadModules() is then called
app/code/mage/core/Model/Config.php
Inside the loadModules function the following methods are called
- $this->_loadDeclaredModules();
- $this->loadModulesConfiguration(array('config.xml',$resourceConfig), $this);
The first loads all the modules configuration files from app/etc/modules
The second method mentioned then goes through each moduels and loads the configuration from each modules etc folder.