LibreSOC Still Striving To Produce An Open-Source Hybrid CPU/GPU Built On OpenPOWER
LibreSOC remains the very ambitious project of creating a fully open-source hybrid CPU/GPU SoC but with a very uphill battle still in front of them.
LibreSOC has been after designing a hybrid CPU/GPU that is 100% open-source. The project originally stated off as aiming to be a RISC-V Vulkan accelerator back when the project was known as Libre RISC-V. But they ultimately dropped RISC-V for aiming to be an OpenPOWER ISA based design over not needing NDAs and other organizational matters that turned them off to using RISC-V.
The original plans for this open-source accelerator have just focused on being able to deliver 1280 x 720 @ 25 FPS and around 5~6 GFLOPS.... Even back in 2018 when those goals were shared it was rather weak then and with each passing year just looks much weaker especially with their hopes of finding this open-source SoC to be used on consumer devices like Chromebook-type laptops and more.
Luke Kenneth Casson Leighton who continues to lead the LibreSOC effort presented today at FOSDEM 2021 over the recent and ongoing work for this hybrid CPU/VPU/GPU OpenPOWER initiative that would be fully open-source including for the hardware design.
LibreSOC as part of its OpenPOWER usage is still proposing a "Simple-V" vector extension to make the ISA more appropriate for conventional graphics workloads. The LibreSOC is being designed in NMIGEN as a Python-based HDR. Luke shared during this year's FOSDEM presentation that LibreSOC aims to do "the same tricks that IBM POWER10 and Apple M1" can do thanks to OpenPOWER being a RISC architecture.
The eager open-source enthusiast also believes, "Libre-SOC combines the best of historical processor designs, co-opting and innovating on them (pissing in the back yard of every incumbent CPU and GPU company in the process)."
We'll see though if/when LibreSOC manages to reach its goal of a mass-volume, low-power SoC for tablets, smartphones, and other devices and if the performance is sufficient to achieve any level of industry adoption.
In addition to designing their own OpenPOWER SoC that is low-power and suitable for GPU/VPU purposes with their custom extension, for achieving the graphics software support has been hopes of leveraging the likes of Mesa LLVMpipe and Vulkan-CPU/Kazan for providing OpenGL/Vulkan on top of their optimized SoC. The focus at this point is solely on being an embedded SoC and not for providing say a PCIe-based accelerator / graphics card. Those past open-source graphics card efforts like Project VGA have all ended up failing as well.
The FOSDEM 2021 LibreSOC presentation can be viewed here (PDF).