How do I downgrade from MySQL 5.5 to MariaDB 5.3/5.2/5.1?
This question is outdated. MariaDB 5.5 is out now, so when moving from MySQL 5.5 you should go directly to MariaDB 5.5 and not to any earlier version of MariaDB.
As of the current writing, MariaDB 5.5 based on MySQL 5.5 is not released yet. You may have an environment where you have upgraded to MySQL 5.5 or are currently using MySQL 5.5 but you want to now run MariaDB 5.3. For this to work, you need to downgrade your installation as MariaDB 5.3/5.2/5.1 is based on MySQL 5.1.
The MySQL Reference Manual talks about downgrading MySQL. Note the change in
mysql.proc.comment. The table is seen to be corrupt and in need of repair. You might want to run
mysql_upgrade in MariaDB or a user left a comment to perform:
ALTER TABLE `mysql`.`proc` MODIFY COLUMN `comment` CHAR(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL DEFAULT '';