"opam var arch" gives x86_64 after switching to 4.02.3+32bit : how to fix that?

[Naereen]

Hi there.
I'm trying to reproduce use the (old) project https://github.com/dbuenzli/rpi-boot-ocaml/ to install a compiler of OCaml for ARM 32 bits.
I can't proceed, as I described in dbuenzli/rpi-boot-ocaml#12, because when I install then switch to 4.02.3+32bit, the opam var arch outputs x86_64 instead of x86_32 :

$ opam switch 4.02.3+32bit
# Run eval $(opam env) to update the current shell environment
$ eval $(opam env)
$ opam var arch
x86_64

Could someone please help me?

I tried my switch and it works: if I compile with ocamlopt a test OCaml file, it produces a binary for 32 bits (Intel).

Thanks in advance, kind regards 😃, @Naereen.