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Comment by gigatexal | Hacker News Reader

what GPUs are compatible with this?

AMD Radeon GPUs are known to work, provided you get one which has good Linux support. They need to have all open source bits because of course you cannot run x86 blobs on RISC-V, so for example Nvidia with the normal drivers would be impossible.

The getting started guide has a few specific model suggestions: https://starfivetech.com/uploads/hifive-unmatched-getting-st...

I have the Hifive Unmatched board with an AMD GPU and anything graphics related is extremely slow, to the point that launching and using a browser is unusably slow (I mostly use it via SSH). Might be related to the low amount of PCIe bandwidth available (AFAICT everything PCIe so both graphics and NVMe share a single x8 PCIe bus). Also there is a recent patch for the kernel that removes some unaligned memory accesses in copy_to/from_user which should speed things up, but I haven't tried the new kernel yet [1]

Nevertheless it is a useful board for testing software on RISC-V, e.g. I mostly use it to test the OCaml compiler and related programs on it.

[1] https://lore.kernel.org/lkml/mhng-423e8bdb-977e-4b99-a1bb-b8...

Nah, there is NO way PCIe bandwidth is to blame. x8 is a lot! My MACCHIATObin runs an RX 480 over gen2 x4 — with a 4K display Firefox WebRender is totally usable (actually the browser is CPU bound, just scrolling is 60fps consistently), SuperTuxKart gets into the 90fps range.

My question is how would one determine which GPUs are compatible with this?

I guess any GPU that works on x8 PCIe gen 3 and can power itself from that or supply its own external power? (Datasheet says the fully loaded board is 150W btw.) You'd probably have to limit yourself to whatever has open source drivers for Linux.

I am running RX 570 with PCIe + 6-pin connector for the power. These works out-of-the-box due to open source drivers. Older Nvidia cards work too, but you would need to go with older cards as you need Nouveau driver. I believe someone recently used AMD RX 6700XT, which is a bit insane.

The bottleneck here is SoC, not the GPU. With HW decoding on the GPU I can play 4K 60fps trailers on Unmatched just fine.

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