I am trying to test my own DAX file system using User Mode Linux (UML). I can add my file system to the Linux source and compile it for UML. For testing purpose, I need to pass a block device (e.g., a disk) from the host to UML, so that I can mount it inside UML. I couldn't find any relative solution from the "User Mode Linux HOWTO" site. I would appreciate if anyone can help.