The fifth-year senior started all 13 games last year and was the only returning starter on the line. He had 30 tackles, 2.5 tackles for loss and a forced fumble in 2013 after two years as a reserve.
In a statement Thursday, coach Larry Fedora said Farmer worked hard in preseason and didn't let his uncertain status affect his preparation.
The No. 23 Tar Heels host Liberty in Saturday's opener.