openzfs module fails to load

[Eugen]

Freebsd 12.1 STABLE 360074

openzfs-kmod and openzfs ports build just fine.

/boot/loader.conf:
zfs_load="NO"
openzfs_load="YES"

/etc/rc.conf:
zfs_enable="NO" (or "YES", it doesn't matter)

With above settings openzfs.ko module does not load at boot.
zfs.ko module is loaded instead. kldstat:

Id Refs Address                Size Name
 1   40 0xffffffff80200000  1143a00 kernel
 2    1 0xffffffff81345000   37add8 zfs.ko
 3    2 0xffffffff816c0000     a240 opensolaris.ko
 4    1 0xffffffff816cb000     29f0 coretemp.ko
 5    1 0xffffffff816ce000     ec08 aesni.ko
 6    1 0xffffffff81e90000     c6a0 fuse.ko
 7    1 0xffffffff81e9d000    f2890 nvidia-modeset.ko
 8    1 0xffffffff81f90000  11f7ca0 nvidia.ko
 9    1 0xffffffff83188000      e20 cpuctl.ko
10    1 0xffffffff83189000     1440 uhid.ko
11    1 0xffffffff8318b000     2078 ums.ko
12    1 0xffffffff8318e000     7f80 tmpfs.ko
13    1 0xffffffff83196000     1990 fdescfs.ko
14    1 0xffffffff83198000    16078 ext2fs.ko
15    1 0xffffffff831af000     3c74 geom_linux_lvm.ko

After:
kldunload zfs
kldload openzfs

dmesg shows this:

[98] link_elf_obj: symbol sdt_probe_func undefined
[98] linker_load_file: /boot/modules/openzfs.ko - unsupported file type

Any ideas why openzfs module does not load?

Thanks,
Eugen