Interesting. Do you know of any good SoK papers or articles that summarize the current state of the art, or explains this genealogy?
2018 video by Ian Pratt covers Xen, uXen and AX (2005-2015), https://news.ycombinator.com/item?id=44135977#44141164. Citrix acquired XenSource. Pratt left to work at Bromium, acquired by HP (which previously acquired BIOS company from Bromium co-founder). The former CTO of XenSource co-founded Qumranet (KVM), acquired by RedHat.
AWS began with Xen, then migrated to a subset of KVM. Nitro used Arm hardware to virtualize I/O (storage, network) paths, leaving KVM responsible for x86 CPU and memory virtualization, https://www.youtube.com/watch?v=e8DVmwj3OEs & https://news.ycombinator.com/item?id=24515019#24516523. Parallels could be drawn to the Apple T2 enclave (Arm) coprocessor being used for disk encryption on x86 Apple Macbooks.
Under the "Confidential Computing" umbrella, Intel has TDX and a new (closed?) hypervisor on servers, using SGX and new hardware privilege levels.
Apple recently added Secure eXclaves to iOS, and Apple Silicon hardware supports nested virtualization, which is what Google pKVM uses on Pixel (and upcoming ChromeOS?) devices, https://news.ycombinator.com/item?id=43314657
For production code, pKVM deserves attention because it's open (upstreamed to mainline Linux), exists in the real world (Pixel phones), stands in stark contrast to Apple's neutered iPads and has the potential to improve upon TrustZone security, https://news.ycombinator.com/item?id=41523758.
Finally, to bring this thread back to Barrelfish, Google OpenTitan open silicon root of trust (OCP servers, Chromebooks) is partly under Pulp Platform research, alongside Snitch (descended from Barrelfish research) open hardware from ETH Zurich. So progress is being made in both mainstream-compatible systems software and greenfield hardware cores.
(hopefully readers can correct any errors or gaps above)
Barrelfish (multikernel) and your username made me think of manycore systems and the scheduling challenges we will surely face as systems become more heterogeneous. I'm in a period of trying to learn more about that. Any and all recommendations are much appreciated.
> compute.. is handled by 140 of Tenstorrent's Tensix cores, each of which is composed of five "Baby RISC-V" cores, a pair of routers, a compute complex, and some L1 cache.. Tensix cores account for 700 of the 752 so-called baby RISC-V cores on board.. TT-Metalium low-level programming model.. kernels themselves are plain C++ with APIs.. Tenstorrent aims to support running any AI model on its accelerators using commonly used runtimes like PyTorch, ONNX, JAX, TensorFlow, and vLLM.
Legion from the Stanford research team that lead to CUDA, https://legion.stanford.edu/ & https://elliottslaughter.com/2024/02/legion-paper-history
> A novel mapping interface provides explicit programmer controlled placement of data in the memory hierarchy and assignment of tasks to processors in a way that is orthogonal to correctness, thereby enabling easy porting and tuning of Legion applications to new architectures.. Legion is developed as an open source project, with major contributions from LANL, NVIDIA Research, SLAC, and Stanford.
I assume you're also aware of the Oxide and Friends podcast, and the Microarch Club podcast?
Thanks for the pKVM tip, and the connection between OpenTitan and Barrelfish.
Speaking of security and open-source hardware, shameless plug of stuff I work on:
- dev.tillitis.se (FPGA-based OSHW RoT)
- system-transparency.org (related to CC, TDX, SNP)
- sigsum.org
Virtio on Xen is still a work in progress, https://wiki.xenproject.org/wiki/Virtio_On_Xen