Been playing around for days and got it working on Unraid VM Xpenology.
DSM 6.2.2, 3615xs 24922 (latest), 1.03b Jun's loader
Step-by-step guide working for me:
Create VM use CENTOS
First scroll down make sure it's set to br0
Either copy MAC and edit synoboot.img , or edit MAC / SN after generation use OSFmount
set time-out in synoboot.img to 10 secs
Copy edited synoboot.img to wanted location and set permissions to 7777
Host Passtrough (i'm on i3-6100)
Choose initial memory
Set machine as Q35-3.0
Use SeaBIOS
Primary vDisk Location eg /mnt/cache/xpenology/synoboot.img (use USB, manual)
2nd vDisk location either /dev/sd*** or create Manual eg /mnt/cache/xpenology/vdisk.img (use SATA, enough gb-space, qcow2)
deselect start VM after creation and click apply
edit created VM, right top corner to XML view
change br0 model type from VIRTIO to e1000e
change hdd bus sata controller from 0 to 1
update and back out to main VM page Unraid
start VM, right after start go to VNC remote
Since you changed timeout to 10 you will now be able to select the bottom line of the loader from 1st option Baremetal to 3rd option VMware
I know you can change default option in synoboot to VMware as well but it might occur your's will only work on Baremetal, this way you don't have to re-edit your'e synoboot.img again...
done and good luck , let me know if this worked out for you !
Gr, Marc