git bisect start
# good: [a6409cad137621e2b43d9f49c757fbc996539e85] UBUNTU: Ubuntu-4.4.0-28.47
git bisect good a6409cad137621e2b43d9f49c757fbc996539e85
# bad: [2a1e175b928aefed1fd3c90c98e845f764fa8684] UBUNTU: Ubuntu-4.4.0-31.50
git bisect bad 2a1e175b928aefed1fd3c90c98e845f764fa8684