Use ESXi VM, loading redpill img/vmdk on Sata Controller 0 Port 0 (0:0)
LSI Passthrough on the VM, disk/s attached to the HBA
Regarding on the strange behaviour of the synoboot reservation, even if DiskIdxMap SasIdxMap and SataPortMap are defined correctly, redpill will reserve itself /dev/sdA (it's loaded correcly on /dev/synoboot) so the first disk on the HBA is always shown as /dev/sdB or more based on SataPortMap.
This issue is not present if redpill setup on a SCSI Controller instead of Sata Controller but no /dev/synoboot is created (but DSM install will fail - if DSM already installed it will work).
Replication:
Regarding on the strange behaviour of the synoboot reservation, even if DiskIdxMap SasIdxMap and SataPortMap are defined correctly, redpill will reserve itself /dev/sdA (it's loaded correcly on /dev/synoboot) so the first disk on the HBA is always shown as /dev/sdB or more based on SataPortMap.
This issue is not present if redpill setup on a SCSI Controller instead of Sata Controller but no /dev/synoboot is created (but DSM install will fail - if DSM already installed it will work).