When SiFive introduced its HiFive Unmatchd RISC-V desktop motherboard for developers last year, it was clear from the start that sooner or later an enthusiast would attempt to try using its U7 SoC for something it is not meant for: general PC usage with high-performance graphics and video decoding. That time has come as an enthusiast has managed to make AMD's Radeon RX 6700 XT work with a RISC-V SoC under Linux.
Computer scientist René Rebe decided to prove that the SiFive HiFive Unmatched not only can run Linux, but can also use a high-performance graphics processor, reports Hackster.io. To do so, he spent 10 hours patching the Linux kernel to add support for AMD's Radeon RX 6700 XT graphics card as well as the Mesa Gallium 21.1.5 driver.
Rebe not only managed to make AMD's Radeon RX 6700 XT display Linux's GUI, but he even made it render 3D graphics in a hardware-accelerated mode and decode video. He did not try to launch games (there are certain limitations with video decoding) but as this is the world's first attempt to make a high-performance GPU work with RISC-V, the endeavor can be considered a success.
SiFive's HiFive Unmatched board with the Freedom U740 SoC has all the PC I/O interfaces that PC users are used to, including PCIe 3.0 x8/16, M.2 slots, and USB ports. To that end, it is possible to install almost any piece of modern hardware into a PC powered by the HiFive Unmatched board. After all, the board is designed for developers working on client PC and server software for upcoming RISC-V SoCs. There is a limitation though: Linux does not support RISC-V properly since most RISC-V-based chips are microcontrollers that cannot run high-level operating systems. While there are some RISC-V SoCs that can run them (e.g., the Freedom U740), they are not particularly fast.
There are more details about the SiFive Unmatched RISC-V motherboard with AMD's Radeon RX 6700 XT experiment at Bits inside by René Rebe YouTube channel.