SiFive HiFive Unmatched Hands-On, Initial RISC-V Performance Benchmarks
Written by Michael Larabel in Computers on 24 September 2021. Page 1 of 4. 76 Comments

A few weeks ago I finally received the HiFive Unmatched from SiFive as their flagship RISC-V development board. As a reminder this is their mini-ITX development board that is powered by their U740 SoC and features 16GB of DDR4 system memory, one PCI Express x16 slot that can work with AMD Radeon graphics cards on Linux, and other features. It's been a delight playing with this developer platform and enclosed are some early benchmarks as well showing off the U740 performance as well as how the Linux software support/performance has been evolving.

The SiFive HiFive Unmatched is what many developers and enthusiasts have long been waiting for and began shipping this summer after being announced at the end of last year. The mini-ITX board is powered by a 24-pin ATX power supply connection, the PCI Express x16 slot (at PCIe x8 speeds) can power a graphics card if wanting to use this board as a workstation, 16GB of DDR4 is sufficient for most of today's development needs, there is integrated Gigabit Ethernet, both microSD and NVMe M.2 storage support, one M.2 E-key slot for WiFi/Bluetooth, and four USB 3.2 Gen1 ports.

The SiFive FU740 SoC that powers this development board has four SiFive U74 cores with one SiFive S7 core.

The HiFive Unmatched is quite a capable board for those wanting to dabble with early RISC-V development work and other bring-up for this very promising ISA. Pricing on the HiFive Unmatched is at $665 USD, which certainly isn't at Raspberry Pi level pricing, but not too bad either considering the limited production and this board's specs. Hopefully with time SiFive will be able to produce a more value optimized board for those wishing to experiment with RISC-V on a greater budget -- well, SiFive also has their Inventor Kit for getting kids involved with (RISC-V) programming.

For those wondering about the PCI Express 3.0 x16 slot, it's limited to x8 lanes but can drive a graphics card. SiFive's documentation lists the Radeon HD 6000 series (not to be confused with the current RX 6000 series) and RX 500 (Polaris) series as being supported. AMD's open-source Linux graphics driver stack allows for it to be built for RISC-V but various ISA quirks with the driver seems to be what is limiting the range of supported graphics cards by the AMDGPU driver on the HiFive Unmatched. Trying a Radeon RX 5000 series Navi graphics card did yield no working display but going for a Radeon RX 580 and older Radeon HD 6770 graphics card did work without issue. NVIDIA graphics are obviously unsupported until if/when they release a RISC-V Linux driver.

Aside from having to be aware of GPU support caveats if wanting to use a display with the HiFive Unmatched, the experience was quite pleasant and easy to get off to the RISC-V races.


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