Open Source Summit + Embedded Linux Conference + OSPOCon 2021

Static partitioning is becoming increasingly common in embedded. A static hypervisor, such as Xen dom0less, is employed to split the hardware resources into multiple domains and run a different OS in each domain. For instance, Linux and Zephyr. Only the simplest static partitioning configurations don't involve any data exchanges between the domains. Often, communication and data exchanges between two or more environments are required to complete the data processing pipeline that implements the target application. However, the VM-to-VM communication mechanisms available in static partitioning configurations are typically more limited compared to general-purpose hypervisors. For example, PV drivers are not available to Xen dom0less domains. This presentation will discuss the need for communication in static partitioning setups and it will present the technical challenges involved in getting traditional communication methods to work, including Xen PV drivers and VirtIO. The talk will also provide simpler alternatives based on shared memory and interrupt notifications to set up domain-to-domain data streams: simpler techniques that are easily exploitable both by Linux and by tiny baremetal applications as well.