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Explore how RISC-V Linux kernel development is adapting to support the RVA23 profile in this 25-minute conference talk from the Linux Plumbers Conference. Learn about RISC-V International's introduction of hardware profiles to manage the growing number of RISC-V extensions, with RVA23 defining key extensions for performance-focused hardware including 64-bit, Vector, Hypervisor, and CFI capabilities. Understand the current kernel approach of building a single kernel compatible with all RISC-V hardware by compiling C code with minimal extensions (rv64imac) and assembly code with rv64imafdvc, requiring runtime detection and selective enabling of additional extensions. Discover the performance limitations of this approach, including the inability to use performance-enhancing extensions like bitmanip in kernel C code and the overhead of runtime configuration checks that scale exponentially with the number of extensions. Examine how adapting the kernel to assume RVA23 profile support can eliminate these issues by enabling compilation with performance-enhancing instructions, reducing runtime checks for most extensions, and providing confident support for extensions that modify userspace ABI. Gain insights into the proposed patches and implementation strategies for creating an RVA23-compatible kernel that maximizes the benefits of this standardized profile approach.
