Index: includes/install.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/install.inc,v
retrieving revision 1.144
diff -u -p -r1.144 install.inc
--- includes/install.inc	13 Nov 2010 23:07:15 -0000	1.144
+++ includes/install.inc	20 Dec 2010 01:49:38 -0000
@@ -242,12 +242,19 @@ function drupal_detect_database_types() 
     }
   }
 
+  drupal_set_message('List of available PDO drivers:');
+  drupal_set_message('<pre>' . print_r(PDO::getAvailableDrivers(),true) . '</pre>');
   foreach ($drivers as $driver => $file) {
     $class = 'DatabaseTasks_' . $driver;
     $installer = new $class();
+    drupal_set_message("Checking if $driver is installable.");
     if ($installer->installable()) {
+      drupal_set_message('yes');
       $databases[$driver] = $installer->name();
     }
+    else {
+      drupal_set_message('no');
+    }
   }
 
   // Usability: unconditionally put the MySQL driver on top.
@@ -328,6 +335,7 @@ abstract class DatabaseTasks {
    * Ensure the PDO driver is supported by the version of PHP in use.
    */
   protected function hasPdoDriver() {
+    drupal_set_message("Checking if {$this->pdoDriver} is one of the available drivers");
     return in_array($this->pdoDriver, PDO::getAvailableDrivers());
   }