RISC-V With Linux 5.16 Enabling Open-Source NVIDIA Driver As Part Of Default Kernel

The RISC-V architecture updates were sent out on Friday for targeting the nearly-over Linux 5.16 merge window.

The RISC-V updates for Linux 5.16 include support for RISC-V 32-bit "rv32" randconfig kernel builds for random configurations to stress the build system / different code paths, supporting the time namespace in the VDSO, improving the XIP port, DeviceTree clean-ups, and more.

The default configuration "deconfig" for the RISC-V Linux kernel build has also been updated with the open-source NVIDIA "Nouveau" driver now included as part of the default modules being built. From the Nouveau driver side, there are no changes this cycle benefiting RISC-V but basically the defconfig acknowledgement that the driver should work there when built.

NVIDIA hasn't made any public RISC-V Linux driver available but it turns out the Nouveau driver should now work fine for this open-source processor ISA. With the likes of SiFive's HiFive Unmatched great developer board they recommend the likes of older AMD Radeon graphics cards using its stellar open-source stack with the older generations particularly working out well on RISC-V but it turns out Nouveau for NVIDIA cards should play fine too, assuming the kernel module is being built/included.

Though RISC-V users are still likely best off using Radeon graphics over NVIDIA with Nouveau... Nouveau for the GTX 900 series and newer remains in rough shape, including the lack of re-clocking support that leads to being bound to the rather low boot frequencies of the graphics processor / video memory. That re-clocking limitation has made Nouveau a disappointment for recent generations of NVIDIA GPUs wanting to run on an open-source driver. The best Nouveau driver support right now remains with the old GeForce GTX 600 / 700 "Kepler" graphics cards or GTX 750 "Maxwell1" graphics cards... So if you happen to have those aging graphics cards around, it should work fine with RISC-V otherwise you are likely better off using a recommended Radeon graphics card for your RISC-V encounters.

For those interested in RISC-V for being open-source, the GTX 600 / 700 series with Nouveau is also a sweet spot there for being the last generation before NVIDIA mandated signed firmware blobs. With GTX 600 / 700 series, no firmware binaries are necessary but with newer GPUs is where those blobs are required and what has also obstructed the whole power management / re-clocking situation.

See this pull request for the complete listing of RISC-V changes for Linux 5.16.