This page gives an overview of upstream projects. If you miss information or find mistakes, please edit.

ABIs, APIs, and other conventions

The main document for RISC-V ABI/ELF-related information is the RISC-V ELF psABI document, which can be found here: https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md

An overview of other RISC-V ABI/API related documents can be found here: https://github.com/riscv/riscv-elf-psabi-doc/blob/master/README.md

The following RISC-V ABIs are currently defined:

• 32-bit

  • ILP32, ILP32F, ILP32D, ILP32E

• 64-bit

  • LP64, LP64F, LP64D, LP64Q, LP64E

Calling conventions

There are two calling conventions for GP registers in the RISC-V ecosystem:

• Standard ABI (sometime also called UABI): https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#integer-register-convention-

• EABI (targeting embedded systems): https://github.com/riscv/riscv-eabi-spec/blob/master/EABI.adoc

Default library path

The rich set of APIs has the consequence, that glibc's default library path includes a subdirectory for the actual ABI (e.g. "/usr/lib64/lp64d" for LP64D).
These default paths are defined here: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/riscv/configure.ac;

Binutils

The GNU Binutils are a collection of binary tools (GNU linker, GNU assembler, many other excellent tools such as gprof).

• Binutils Homepage

• Source Release Page

RISC-V maintainers

• Andrew Waterman (SiFive)

• Palmer Dabbelt (Google)

• Jim Wilson (SiFive)

• Nelson Chu (RIVOSINC)

Releases

Rule of thumb: Binutils (GNU linker, GNU assembler, tons of other excellent tools) releases twice per year (mid July and mid January).

• Binutils 2.41 (30 Jul 2023)

• Binutils 2.40 (14 Jan 2023)

RISC-V status

• RV32GC = RV32IMAFDC_Zicsr_Zifencei is implemented

• RV64GC = RV64IMAFDC_Zicsr_Zifencei is implemented

• Unratified extension support is kept in staging branches here: https://github.com/riscv/riscv-binutils-gdb

GCC

The GNU Compiler Collection (GCC) includes front ends for C, C++, Objective-C, Fortran, Ada, Go, and D, as well as libraries for these languages (e.g. libstdc).

• GCC Homepage

• Source Release Page

RISC-V maintainers

• Andrew Waterman (SiFive)

• Palmer Dabbelt (RIVOSINC)

• Jim Wilson

• Kito Cheng (SiFive)

GCC RISC-V community meetings

• Schedule: biweekly, Thursday 7 am (PST), starting on Mar 11, 2021

• Organized by Wei Wu (PLCT)

• Public announcement: https://www.mail-archive.com/gcc@gcc.gnu.org/msg94197.html

RISC-V GCC Patchwork Sync meetings

• Schedule: weekly, Tuesday UTC +0 02:30 p.m, starting on 2023-04-18

• Organized by Palmer Dabbelt (RIVOSINC)

• Public announcement: https://docs.google.com/document/d/1bW2jgRmhYdHz7oVw5EUcXVAv4_cfuBaZ5bhVG1pUnIo

Releases

Rule of thumb: GCC closes the merge window for the next release in mid-November (once per year).

• GCC 14 schedule

  • GCC 14 Stage 1 (starts 2024-04-30)

  • GCC 14 Stage 3 (starts 2024-11-16)

  • GCC 14 Stage 4 (starts 2025-01-17)

  • GCC 14.1 release (not defined; possibly May/June)

After stage 3 has started, new functionality may not be introduced.

The upstream release schedule can be found here.

The upstream release timeline can be found here.

RISC-V status

RV32G and RV64G are mostly implemented. However, there is still some optimization potential.

• RV32GC = RV32IMAFDC_Zicsr_Zifencei is implemented

• RV64GC = RV64IMAFDC_Zicsr_Zifencei is implemented

• RV32/64E is supported

• Supported calling conventions: ilp32, ilp32f, ilp32d, lp64, lp64f, lp64d and lp64e

• GCC supports -msave-restore -mno-relax

• Unratified extension support is kept in staging branches here: https://github.com/riscv/riscv-gcc

• RISC-V specific command-line options: https://gcc.gnu.org/onlinedocs/gcc/RISC-V-Options.html

GDB

GDB is the GNU Project debugger.

• GDB Homepage

• Source Release Page

RISC-V maintainers

• Andrew Burgess (Embecosm)

• Palmer Dabbelt (Google)

Releases

GDB major releases are approximately annually. There are typically one or two minor releases each year. This is the typical schedule:

• major release branch/pre-release approximately 1 month before release

• first minor release ("re-spin") approximately 3 months after major release

At the time of writing the most recent release was 14.1, released on 2020-12-03.

RISC-V status

Debugging works on top of PTRACE syscalls. HW-Breakpoint or HW-Watchpoint support is missing.

Glibc

Glibc is the GNU C library.

• Glibc Homepage

• Source Release Page

RISC-V maintainers

• Palmer Dabbelt (Google)

• Andrew Waterman (SiFive)

• DJ Delorie (Red Hat)

• Darius Rad(Bluespec)

Releases

Rule of thumb: Glibc releases twice per year (February and August).

Previous releases:

• glibc 2.38 (2023-07-31)

• glibc 2.37 (2023-02-01)

• glibc 2.36 (2022-07-30)

RISC-V status

• The following ABIs are supported:

  • ILP32, ILP32D, LP64, LP64D

LLVM

The LLVM Project is a collection of modular and reusable compiler and toolchain technologies.

• LLVM Homepage

• Source Release Page

RISC-V maintainer

• Alex Bradbury (lowRISC)

LLVM RISC-V meetings

• Schedule: biweekly, Thursday 8 am (PST), since Sept 2019

• Organized by Alex Bradbury (lowRISC) and Ana Pazos (Qualcomm)

• Public announcement: https://lists.llvm.org/pipermail/llvm-dev/2021-February/148345.html

Releases

• LLVM 17 schedule

  • LLVM 17.0.6  (28 Nov 2023)

The upstream release page can be found here.

RISC-V status

• RV32GC = RV32IMAFDC_Zicsr_Zifencei is implemented

• RV64GC = RV64IMAFDC_Zicsr_Zifencei is implemented

• RV32E is not supported

• Some non-ratified extensions have been merged mainline (they need the flag -menable-experimental-extensions to enable them):

  • Bitmanip v1.0

    • b, zba, zbb, zbc, zbe, zbf, zbm, zbp, zbr, zbs, zbt, zbproposedc

  • Vector v1.0
    
    

    • Example command for building: clang --target=riscv64-unknown-elf -march=rv64gcv -menable-experimental-extensions 

  • Floating-point v0.1

    • zfh

• LLVM supports -msave-restore -mno-relax

• RISC-V specific command-line options: https://clang.llvm.org/docs/ClangCommandLineReference.html#riscv

• LLVM's extension parsing code: https://github.com/llvm/llvm-project/blob/main/clang/lib/Driver/ToolChains/Arch/RISCV.cpp

Newlib

Newlib is a C standard library implementation intended for use on embedded systems.

• Newlib Homepage

• Source Release Page

RISC-V maintainer

• Kito Cheng (SiFive)

Releases

Rule of thumb: Newlib releases once per year.

Last releases:

• Newlib 4.3.0 (20 Jan 2023)

RISC-V status

RV32 and RV64 are supported. Still, there is optimization and completeness potential.