trying to repeat on s390x what worked on aarch64 ...

OBS_WORKER_DISK=/dev/mapper/3600a098051764b2d515d436d66416b4f
wipefs -f -a $OBS_WORKER_DISK
modprobe zram num_devices=1
modprobe bcache
echo 8G > /sys/block/zram0/disksize
wipefs -f -a /dev/zram0
make-bcache --wipe-bcache --block 4k --bucket 2M -B $OBS_WORKER_DISK -C
/dev/zram0
# up to here it seemed to work, but:
echo /dev/zram0 > /sys/fs/bcache/register
-bash: echo: write error: Invalid argument

in dmesg:
[1256250.924470] zram: Added device: zram0
[1256258.363017] zram0: detected capacity change from 0 to 8589934592
[1256269.146000] bcache: register_bcache() error opening /dev/dm-2: Not a
bcache superblock
[1256275.462897] bcache: register_bcache() error opening /dev/zram0: Not a
bcache superblock

so the written superblock is not recognized ... endianess issue ?