Ocaml-5.0.0~alpha1 + utop + #require "domainslib";;

Error: Reference to undefined global `Virtual_atomic’

Same error with a plain toplevel, but more details.

# #require "domainslib";;0~alpha1/lib/lockfree/lockfree.cma: loaded
Error: Reference to undefined global `Virtual_atomic'

There is a long discussion about this issue here: https://discuss.ocaml.org/t/a-tutorial-on-parallel-programming-in-ocaml-5/

1 Like

In the interests of not breaking everyone’s toplevels just before OCaml 5.0 is released, I’ve marked lockfree.0.3.0 as unavailable in the opam repository. If you opam update shortly, it should recompile utop with the older lockfree.0.2.0 and things should work again.