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

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 (SiFive)

Releases

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

• Binutils 2.35 schedule:
  • Binutils 2.35 (2020-07-24)
  • Binutils 2.35.1 (2020-09-19)
  • Binutils 2.35.2 (2021-01-30)
• Binutils 2.36 schedule:
  • Binutils 2.36 (2021-01-24)

RISC-V status

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

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 (Google)
• Jim Wilson (SiFive)
• 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

Releases

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

• GCC 11 schedule
  • GCC 11 Stage 1 (starts 2020-04-30)
  • GCC 11 Stage 3 (starts 2020-11-16)
  • GCC 11 Stage 4 (starts 2021-01-17)
  • GCC 11.1 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.

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 10.1, released on 2020-10-24. Dates for branching (and hence release) of GDB 11 have yet to be announced.

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 2.32 (2020-08-05)
• glibc 2.33 (2021-02-01)
• glibc 2.34 (2021-08-01)

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 12 schedule
  • LLVM 12.0.0 RC1 (branching) (2021-01-26)
  • LLVM 12.0.0 RC2 (2021-02-23)
  • LLVM 12.0.0 final (2021-03-02)

The upstream release page can be found here.

RISC-V status

• RV32GC = RV32IMAFDC is implemented
• RV64GC = RV64IMAFDC 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 v0.93
    • b, zba, zbb, zbc, zbe, zbf, zbm, zbp, zbr, zbs, zbt, zbproposedc
  • Vector v0.10
    • z, zvamo, zvlsseg
    • Example command for building: clang --target=riscv64-unknown-elf -march=rv64gcv0p10 -menable-experimental-extensions 
  • Floating-point v0.1
    • zfh
• LLVM supports -msave-restore
• 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 3.3.0 (2020-01-22)
• Newlib 4.0.0 (2020-11-17)
• Newlib 4.1.0 (2020-12-18)

RISC-V status

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