[oshug] OSHUG #42 — Chips Pt. 3, Thursday 18th June.

Andrew Back arback at computer.org
Thu May 28 15:40:26 UTC 2015


Registration is now open for the June meeting, details of which can be
found below.




Event #42 — Chips Pt.3 (BERI, Do we need separate Hardware
Construction languages? OpenTransputer)

18 June 2015, 18:00 - 20:00 at BCS London, 1st Floor, The Davidson
Building, 5 Southampton Street, London, WC2E 7HA.

  Registration: http://oshug.org/event/42

This will be the third OSHUG meeting exploring the topic of silicon
chip design, with talks on the Bluespec Extensible RISC
Implementation, another asking whether we need separate hardware
construction languages, and a third talk on an open source
implementation of the Transputer.

— BERI: An open RISC softcore for research and experimentation

BERI (the Bluespec Extensible RISC Implementation) is a softcore
processor jointly developed by SRI International and The University of
Cambridge. It implements a superset of the MIPS III ISA in Bluespec, a
high-level HDL and supports a fully open source, permissively
licensed, software stack comprising the FreeBSD operating system and
the LLVM compiler suite. This talk will describe the design of the
BERI processor and its use.

BERI was created to facilitate experimentation at the boundaries
between CPU architecture, operating systems, and programming
languages. It runs in Altera and Xilinx FPGAs, including the NetFPGA
10G board. At 100MHz, it is fast enough to use as a real computer
(albeit a fairly slow one).

The talk will discuss the BERI softcore, jointly developed by The
University of Cambridge and SRI International and the associated open
source software stack. BERI, the Bluespec Extensible RISC
Implementation, is a 64-bit MIPS implementation in Bluespec, a
high-level hardware description language. It implements the
instruction set that debuted in the MIPS R4000 core in 1991, and
therefore a set that is free of patents owing to its age. In spite of
this, it is a relatively modern 64-bit architecture and is well
supported by open source systems.

The FreeBSD port to BERI required minimal changes, which were shipped
as part of the FreeBSD 10.0 release, and runs unmodified userland
64-bit MIPS code. BERI can run in simulation at a speed acceptable for
testing but not for general usage or in an FPGA at 100MHz. The BERI
design supports multiple cores on a single FPGA and work is ongoing to
support multicore across boards connected with a low-latency

Jonathan Woodruff received his undergraduate degree from the
University of Texas, and Masters and PhD from the University of
Cambridge. Jonathan is a key developer of the BERI open-source
research processor and its CHERI extension for memory safety. Jonathan
is interested in hardware prototyping in FPGA to support full-system
design exploration and has implemented a variety of flexible hardware
components, including a many-core cache emulator, a multi-threaded ARM
core, and many components of the BERI ecosystem.

— Do we need separate Hardware Construction Languages?

Modern Hardware Construction Languages, including Chisel, HML and the
functional subset of Bluespec, provide powerful circuit description
facilities for netlist printing in the style of the generate
statements found in RTL. The earliest mainstream example was perhaps
Lava. They do not support data-directed control flow, and so differ
greatly from both conventional RTL and C-to-gates or scientific
acceleration HLS (high-level synthesis) tools such as LegUp and Kiwi.

In this talk, Greaves will illustrate the essential differences
between these styles and discuss the motivation for separate
languages, which is a surprising departure when one considers that a
major selling point of Verilog and VHDL was they almost seamlessly
integrated simulation, generative constructs and algorithm expression.
He will also discuss the need for higher-level concurrency primitives
and how they might be provided in hardware construction languages.

David Greaves, PhD, MIET, is a Senior Lecturer at the University of
Cambridge with interests in compiler and hardware design. He has
considerable industrial experience at the CTO/Chief Scientist level
and has led the design of many hardware systems in areas such as
professional audio and broadband access.

His current research area is tooling for high-level simulation and
energy instrumentation for system-on-chip based on transaction-level
modelling (TLM). These enable new hardware architectures to be rapidly
explored under real-world workloads, including accelerators for
scientific workloads.

— OpenTransputer: Reinventing a parallel machine from the past

The OpenTransputer is a re-implementation of the Transputer, a
pioneering microprocessor architecture first released in the 1980s.
The original Transputer was considered revolutionary at its time for
its integrated memory and serial communication links intended for
parallel computing. Including memory and external links on the same
chip made the Transputer essentially a computer on a chip. This
allowed information systems to be designed at a higher level – the
Transputer functioning as a building block for parallel computing

Over the last few years, with the shift to cloud computing there has
been a trend in the world of computing of building large clusters of
powerful computers that serve data to an ever-growing number of client
devices, which themselves only feature tiny and low-power processors.
These include mobile phones and tablets, but will soon also comprise
every other device that connects to the internet, ranging from washing
machines to cars. We think that the Transputer and its unique feature
set make it an excellent processor for the emerging Internet of Things
(IoT), specifically for the connected homes and wearable computing

The OpenTransputer maintains all the ideas of the original device for
concurrency management and interprocess communication. However, the
serial links that were used to connect multiple Transputers are
replaced by a switch that routes messages between cores. Furthermore,
we introduce a new I/O interface that is compatible with the vast
majority of hardware components such as accelerometers and gyroscopes.

Note: Please aim to arrive by 18:15 as the event will start at 18:30 prompt.

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