In case anyone else runs into this. I noticed that both XenServer 6.5 and 7.0 crash at the memory scrubbing stage during boot up when run as a VM within VMware Workstation (and possibly other virtualization products too – I didn’t try it with anything else).
Am guessing the crash happens because the memory is not really available (this being a nested VM) and so the process crashes. Anyhoo, the workaround is to disable memory scrubbing. Check this blog post for instructions.
In brief, the instructions are to add the option
bootscrub=false to the boot options. This is via the file
/boot/extlinux.conf in XenServer 6.5; or via
/boot/grub/grub.cfg in XenServer 7.0.