freebuff binary SIGILL on CPUs without AVX2 (pre-2013 Xeons, etc.)

[PePe-Araya]

Summary

The freebuff binary shipped with codebuff/manicode crashes immediately with SIGILL on CPUs that lack AVX2 instructions (typically pre-2013 hardware). The CLI becomes unusable on otherwise-capable older workstations.

Reproduction

1. Install codebuff / manicode on a Linux machine with a pre-AVX2 CPU.
2. Launch the CLI.
3. freebuff exits immediately with SIGILL.

Error message

❌ freebuff exited immediately (signal SIGILL), which are incompatible with nvm.
Run `nvm use --delete-prefix v24.15.0 --silent` to unset it.
Your CPU may not support the required instruction set (AVX2).
This typically affects CPUs from before 2013.
Unfortunately, this binary is not compatible with your system.

System info:
  Platform: linux x64
  Node:     v24.15.0
  Binary:   /home/<user>/.config/manicode/freebuff

Note: the message conflates two unrelated issues — the SIGILL is caused by missing AVX2, not by nvm. The suggested nvm use --delete-prefix workaround does nothing for this case.

System info

• Platform: Linux x86_64 (Ubuntu 24.04, kernel 6.17)
• Node: v24.15.0
• CPU: Intel Xeon E5-2689 @ 2.60 GHz (Sandy Bridge-EP, 2012)
• CPU flags include: avx, sse4_2, aes — but NOT avx2, bmi2, fma
• Binary path: ~/.config/manicode/freebuff

Request

Could you publish a fallback build of freebuff compiled without -mavx2 (or with runtime CPU feature detection / dispatch)? Sandy Bridge / Ivy Bridge Xeons are still widely used in homelab and self-hosted setups and would benefit from a generic-x86_64 build.

A second, smaller ask: please update the error message to drop the misleading nvm guidance when the actual cause is missing AVX2 — it sends users on a wild goose chase.

Thanks!

[Dhanush908090]

I got this same trouble hoping for fix