how about endianness swapping versions?

I don't suppose we can get variants of CREATE_LIST_{32,64} that say "data structure is the opposite endianness to the kernel's natural one" ? :). QEMU linux-user mode also doesn't emulate set_robust_list because of the problem with the guest's idea of the data structure layout potentially not matching the kernel's, but we also have the case of "big endian guest on little endian host" and vice versa...