> "Section 7
> Multi-Kernel and Multi-Instance OSes.
>
> Multi-kernel OSes like Barrelfish, Helios, Hive, and fos run a small kernel on each core or programmable device in a monolithic server, and they use message passing to communicate across their internal kernels. Similarly, multi-instance OSes like Popcorn and Pisces run multiple Linux kernel instances on different cores in a machine. Different from these OSes, LegoOS runs on and manages a distributed set of hardware devices; it manages distributed hardware resources using a two-level approach and handles device failures (currently only mComponent). In addition, LegoOS differs from these OSes in how it splits OS functionalities, where it executes the split kernels, and how it performs message passing across components. Different from multikernels’ message passing mechanisms which are performed over buses or using shared memory in a server, LegoOS’ message passing is performed using a customized RDMA-based RPC stack over InfiniBand or RoCE network. Like LegoOS, fos separates OS functionalities and run them on different processor cores that share main memory. Helios runs satellite kernels on heterogeneous cores and programmable NICs that are not cache-coherent. We took a step further by disseminating OS functionalities to run on individual, network-attached hardware devices. Moreover, LegoOS is the first OS that separates memory and process management and runs virtual memory system completely at network-attached memory devices."
