GNU MCU Eclipse RISC-V Embedded GCC v7.1.1-1-20170702-* released

Posted on July 2, 2017 by Liviu Ionescu.

Version v7.1.1-1-20170702-0625 is the first GNU MCU Eclipse RISC-V Embedded GCC release. It includes binaries for Windows, macOS and GNU/Linux.

Binary files »

Compliance

This release closely follows the official RISC-V distribution maintained by SiFive.

The current version is based on project riscv/riscv-gnu-toolchain, tag v20170612 (commit f5fae1c) from June 12th, which depends on the following:

• the riscv/riscv-gcc project, commit 16210e6 from from May 15th, 2017
• the riscv/riscv-binutils-gdb project, commit 3f21b5c from May 5th, 2017
• the riscv/riscv-newlib project, commit ccd8a0a from May 2nd, 2017

The supported architectures (-march=) are:

• rv32i[m][a][f[d]][c]
• rv32g[c]
• rv64i[m][a][f[d]][c]
• rv64g[c]

The supported ABIs (-mabi=) are:

• ilp32 (32-bit, soft-float)
• ilp32f (32-bit with single-precision in registers and double in memory, niche use only)
• ilp32d (32-bit, hard-float)
• lp64 (64-bit long and pointers, soft-float)
• lp64f (64-bit long and pointers, with single-precision in registers and double in memory, niche use only)
• lp64d (64-bit long and pointers, hard-float).

The supported libraries are:

march=rv32i/mabi=ilp32
march=rv32im/mabi=ilp32
march=rv32iac/mabi=ilp32
march=rv32imac/mabi=ilp32
march=rv32imafc/mabi=ilp32f
march=rv64imac/mabi=lp64
march=rv64imafdc/mabi=lp64d

Plese note that not all possible combinations of architecture and ABI have libraries.

Changes

Compared to the original RISC-V version, there are no functional changes; the same architecture and API options are supported, and the same combinations of libraries (derived from newlib) are provided.

newlib-nano

The only notable addition is support for newlib-nano, using the --specs=nano.specs option. For better results, this option must be added to both compile and link time (the next release of the GNU MCU Eclipse plug-ins will add support for this).

If no syscalls are needed, --specs=nosys.specs can be used at link time to provide empty implementations for the POSIX system calls.

The nano versions of the libraries are compiled with -Os -mcmodel=medlow, while the regular versions are compiled with -O2 -mcmodel=medany.

Documentation

Another addition compared to the SiFive distribution is the presence of the documentation, including the PDF manuals for all tools.

Binaries

Binaries for Windows, macOS and GNU/Linux are provided. For Windows and macOS, separate installable and plain archives are provided. For Windows and GNU/Linux, both 32/64-bit binaries are provided.

Instructions on how to install them are available in the How to install the RISC-V toolchain? page.

For better control and repetability, the build scripts use Docker containers; all files required during builds are available as a separate gnu-mcu-eclipse/riscv-none-gcc-build project.

Known problems

[2017-09-14 update] Soon after this release was used in real projects, it was discovered that the general configuration of the toolchain was intended more to applications that include a kernel-like environment, and less to bare-metal environments. The main problems are:

• the newlib configuration does not use the underscore syscall function, but the direct names (like write() instead of _write()), calls that are always forwarded to libgloss
• the compiler configuration always links libgloss to the application; libgloss implements all system calls via traps to a unix like kernel.

Both problems were fixed in the v7.1.1-2-20170912 release.

Checksums

The SHA-256 hashes for the files are:

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