Dunning was assigned to the White Sox's alternate camp, Scot Gregor of the Daily Herald reports.
Dunning made a full recovery from Tommy John elbow surgery, but the White Sox have a surfeit of starters currently on the active roster, so the promising right-hander is not needed immediately. Gio Gonzalez figures to be first in line if a fill-in starter is needed while left-hander Ross Detwiler also made the cut as a bulk-inning guy.