Joshua White Ireland >NC

Looking for any info re: Joshua White, father of Luke White, grandfather of John Luke White and Gr Grandpa of Wm Pinkney White. Joshua was supposedly from Ireland. Can't find any records regarding his birth and possible marriage to Luke's mother. I have a strong suspicion that he was born on a ship enroute to North America circa 1750(?). According to William Pinkney's diary Joshua served in Revolutionary War under Geo. Washington. Any info that clears the Joshua mystery up would be greatly appreciated!