G1 revert in 8u ran into the problem. In 8u, G1 calls its adapter CMBitMap, which clashes with our definition in shared/. I suggest we dodge this conflict by renaming shared CMBitMap to MarkBitMap in 10, 9, 8u: http://cr.openjdk.java.net/~shade/shenandoah/rename-markbitmap/webrev.01/ Testing: hotspot_gc_shenandoah Thanks, -Aleksey