He was the son of Óengus mac Nad Froích, the first Christian king of Munster.
However, in the saga Senchas Fagbála Caisil ("The Story of the Finding of Cashel"), he is listed after his brother which would put his reign around 525.
[2] the Laud Synchronisms were written in the interest of the Glendamnach branch and this may explain the exclusion of Feidlimid from it.
[3] He was the ancestor of the Eóganacht Chaisil branch of the family with lands around Cashel in County Tipperary.
However, his mother is called Dearcon who is usually associated with Crimthan, the son of Eochaid mac Óengusa and founder of the Airthir Cliach branch.