RISC-V is an open and free instruction set architecture (ISA). The RISC-V ISA specifications are licensed under a Creative Commons license (CC BY 4.0). Anyone could get the final versions of the user-level ISA specifications and drafts of the compressed and privileged ISA specifications.
Another key feature of the RISC-V architecture that it is scalable and allows multiple implementations. The minimal specification has the commands to store and load, jump and integer arithmetic. It supports the 32-, 64- and 128-bit register sizes: "RV32I, RV64I and RV128I" ("I" stands for integer). This Linux port runs on "RV64IMAFDC" or "RV64GC" ("G" == "IMAFD"):
- I - Integer and basic instructions
- M - Multiply and divide
- A - Atomic operations
- F - Single precision floating point
- D - Double precision floating point
- C - Compressed instructions
At this page one could find the latest information about ALT port status for the new platform - RISC-V (RV64GC). We're building it on the HiFive Unleashed board from SiFive. If you want to test the ALT port (QEMU or HiFive Unleashed) or take part in the development please refer to this page.
- The following Linux kernels have been bare metal tested on SiFive HiFive Unleashed:
- BOOT methods:
- Berkeley bootloader -- DONE
- U-BOOT (link) -- DONE
- Sisyphus port -- IN PROGRESS
- Toolchain -- DONE
- Linux Kernel -- DONE
- X11 -- DONE
- Desktop Environments -- IN PROGRESS
- ALT image (link) -- DONE
- Girar Builder -- DONE
- QEMU image (see below) -- DONE
The RPM/SRPM repository at here.
- Berkeley bootloader utils to merge the linux kernel into the bbl.bin with dummy payload.
- RISC-V specifications
- All Aboard -- cool series of blog posts by Palmer Dabbelt about RISC-V, toolchain, etc.
- OSSDEVCONF-2018 (in Russian)