Releases

• lowRISC with interchangeable Rocket/Ariane CPUs, accelerated block device, and X-windows support
  Release version 0.7, released November 2019
  This release offers a choice of CPUs, a choice of FPGA boards, and most development tools updated to upstream versions

• lowRISC with run/step debugging via JTAG and GDB
  Release version 0.6, released October 2018
  This release updates the Rocket IP to March 2018 and includes compressed instructions and JTAG debugging conforming to the RISCV Debug Specification with custom JTAG DTM (see JTAG internals for details). The root filing system is updated to use the mostly upstreamed Debian repository and the peripheral data path widths are increased to 64-bits for better performance.

• lowRISC with 100MHz Ethernet and Network filing system access
  Release version 0.5, 01-2018
  This preview release provides a complete Ethernet reference design, tools, and NFS root capability. This includes the ability to arp, ping, ssh client and server, mount remote NFS disks, and run a full multi-user system (within the available RAM and FPGA CPU performance limitations) The SD-card interface is promoted to a Rocket peripheral to boost performance. The human interface (keyboard and VGA compatible text display) are integrated as the default Rocket console. We continue to support the Nexys4 DDR FPGA platform, only the Minion is omitted. The tutorial outlines the build procedure and forthcoming releases that we are planning.

• lowRISC with tagged memory and minion core
  Release version 0.4, 06-2017
  This release provides a more complete prototype of tagged memory implementation. This includes the ability to define tag propagation rules and policies that control when encountering unexpected tags should raise exceptions. These features have been incorporated into the Rocket core. An optimised tag cache has also been developed in order to minimise any additional main memory traffic from the use of tags. A simple “minion” core is added to provide an SD-card interface. This system also supports a keyboard and provides a VGA compatible text display. We continue to support the Nexys4 DDR FPGA platform. The tutorial outlines the build procedure and forthcoming releases that we are planning.

• lowRISC with a trace debugger
  Release version 0.3, 07-2016
  In this code release we present a first prototype of the lowRISC debug infrastructure. It extends the untethered lowRISC system with the means to control the system, load programs and trace the software execution. The tutorial outlines the debug system and the future directions we are planning. It demonstrates debugging with the RTL simulation and on the Nexys4 DDR FPGA board.

• Untethered lowRISC
  Release version 0.2, 12-2015
  A code release providing a standalone lowRISC by untethering the Rocket chip. Cores in the original Rocket chip relies on a companion processor to access I/O devices. This release repalce this companion core with actual FPGA peripherals. A tutorial explains how to use this code release and explains the underlying structural changes.

• lowRISC with tagged memory
  Release version 0.1, 04-2015
  A code release builds on the Rocket RISC-V implementation to offer support for tagged memory (see the release blog post). We’ve put together an extensive tutorial on how to use this code release as well as documenting many of the changes made.

Memos

Our first memo describes our plans for tagged memory and minion cores in lowRISC.

Other

Over the summer of 2016 we hosted a group of interns, kindly sponsored by IMC Financial Markets who worked on adding custom acceleraors for video decoding to the lowRISC platform. This work resulted in the creation of several documents:

• A detailed report on what was produced over the summer, what went well and what didn’t, as well as a description of the accelerators.
• A tutorial on adding new stream processors to the video accelerator infrastructure developed over the summer.
• A tutorial on extending lowRISC with new devices.
• A guide describing how to recreate the video decode demo.

Although now over, you may be interested in our project idea list for Google Summer of Code 2015 and for GSoC 2016.