RISC-V Is Sloooow

Fedora builds crawl, commenters brawl: blame the chips, not the blueprint

TLDR: Fedora’s RISC‑V builds are painfully slow, with optimizations disabled and even emulation used, and the team says real server‑grade hardware is needed before it’s a primary platform. Commenters split between blaming chips vs design, push cross‑compiling on x86, and suggest build accelerators—because speed will decide RISC‑V’s future

Fedora’s RISC‑V builds are moving at snail speed, with one core package taking 143 minutes on current boards versus around 30 on mainstream PCs. To save memory, link‑time optimization (a speed trick known as LTO) is switched off, and the maintainer admits he’s leaning on QEMU emulation with 80 “fake” cores just to get through big jobs. New boards are on the horizon, but Fedora says they need real, rack‑ready servers before RISC‑V can be a first‑class architecture.

Cue the comments coliseum. Team “Don’t blame the idea” insists the open chip design, RISC‑V, isn’t the villain—“it’s the chips and unoptimized software,” says rbanffy, comparing today’s pain to ARM’s awkward teenage years. Team “Just cross‑compile it” fires back: build everything on normal x86 PCs and ship the results, with lifis dropping the mic and leni536 asking why that isn’t default. Meanwhile, pragmatists like rbalint chant “bring ccache and firebuild,” hoping build accelerators can shave hours.

And the memes? Users rebrand it Snail‑V, joke that LTO stands for “Long Time Optimizing,” and quip devs are in compile jail. Optimists like IshKebab swear RISC‑V is only “a few years” behind ARM, while skeptics want rack‑ready monsters yesterday. Everyone agrees on one thing: the wait times are the real boss fight

Key Points

  • The Fedora Linux RISC‑V port progressed with triage and 86 package pull requests, many merged and built for Fedora 43.
  • RISC‑V build performance is significantly slower than other architectures; Binutils on riscv64 took 143 minutes vs 25–46 minutes on others.
  • Fedora’s RISC‑V builds currently disable LTO to reduce memory use and build times; typical builders have 4–8 cores and 8–32 GB RAM.
  • New hardware (UltraRISC UR‑DP1000 on Milk‑V Titan, SpacemiT K3 systems) is expected to help, but rackable servers that can build heavy packages under an hour are needed.
  • QEMU with 80 emulated cores builds LLVM 15 in ~4 hours versus ~10.5 hours on a Banana Pi BPI‑F3; plans include starting Fedora 44 builds with a unified kernel image and bringing faster builders.

Hottest takes

"Don't blame the ISA - blame the silicon implementations AND the software" — rbanffy
"fix cross compilation and then compile it on a normal x86_64 server" — lifis
"It's a few years behind ARM, but not that many" — IshKebab
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