Dixi quod… >(This is what I found trying to build openjdk-20, but it’ll be >needed in 21 as well. Even getting to this point took 13½ days >already…) And turns out that this isn’t the cause. In 17, we’ve got src/hotspot/share/memory/allocation.hpp to align all CHeapObj, StackObj, MetaspaceObj, etc. classes; this is gone in 21. So this needs to be brought back instead.