At the Linley Processor Conference today, SiFive, the semiconductor company building chips around the Open RISC-V instruction set has announced the availability of a quadcore processor that runs Linux. We’ve seen RISC-V implementations before, and SiFive has already released silicon-based on the RISC-V ISA. These implementations are rather small, though, and this is the first implementation designed for more than simple embedded devices.
This announcement introduces the SiFive U54-MC Coreplex, a true System on Chip that includes four 64-bit CPUs running at 1.5 GHz. This SoC is built with TSMC’s 28 nm process, and fits on a die about 30 mm². Availability will be on a development board sometime in early 2018, and if our expectations match the reality of SiFive’s previous offerings, you’ll be able to buy this Open SoC as a BGA package some months after that.
So far, there are few tangible details about the SiFive U54-MC, but what we do know looks great. On the software support front, RISC-V support in GCC is stable and mainlined as of the 7.1 release. LLVM is in the process of being submitted, and Linux support is getting there too. Considering no one outside SiFive has this hardware in hand, this is just fine.
The hardware part of this SoC is where things get interesting. This is a truly modern SoC built with a modern process. Typical performance is 1.5 GHz, with 1.7 DMIPS/MHz and 2.75 CoreMark/MHz. Peripherals included in this SoC include a DDR3/4 controller, Gigabit Ethernet, SD card, SPI, UARTs, and the other usual peripherals found in every other processor. Of special interest is the ChipLink interconnect. This is a direct connection to an FPGA where IP blocks run, giving the SoC peripherals like PCIe, USB, MIPI, or other high-speed interfaces.
Below you can check out a few of the relevant slides from SiFive’s announcement today:
We’ve taken a look at SiFive’s RISC-V offerings in the past, most notably in the form of the HiFive I, an Arduino-shaped board loaded up with the SiFive E31 CPU. This is a microcontroller, and a far cry from a quadcore SoC. However, the E31 is a remarkable microcontroller that’s exceptionally fast, capable, and has a surprising amount of support and tutorials behind it. Right now, if you want a microcontroller that’s exceptionally fast, has fast DMA, and can control a ton of WS2812 RGB LEDs, your best options are a Teensy or a BeagleBoard with the fantastic PRUs. The E31 is a contender, though, and with recent, lower cost offerings like the LoFive we’re expecting RISC-V microcontrollers popping up in some very interesting projects soon.
This announcement is just that — an announcement — and our expectations are tempered by the fact that our desire for instant gratification is not satiated right now. SiFive has been doing a lot of work over the past few years, though, and given the release of the HiFive 1, their work in getting trays of their E31 microcontrollers into the hands of engineers, and their honestly fantastic work on their own support forums, there’s no reason to expect this Open SoC is vaporware.