Hi Miles, Thanks for the patch. Could you let me know which architecture and compiler this was broken on? If I had to guess, I'd wager arm32, and you hit this by enabling optimized blake2s? If so, I'm not sure the problem is with weak symbols. Why should CFI break weak symbols? Rather, perhaps the issue is that the function is defined in blake2s-core.S? Are there some CFI macros we need for that definition? Jason