Travis is running containers, so even if you use a i686 rustc, you still benefit from a 64-bits kernel, meaning processes still have the full 4GB of address spa

Travis is running containers, so even if you use a i686 rustc, you still benefit from a 64-bits kernel, meaning processes still have the full 4GB of address space. On an actual i386 linux kernel, this would be limited to 3GB. Maybe it's even less on openbsd (I don't know, but technically, it could be as low as 2GB). That could explain why it works for you and not for them.