I just took a short look at the API and it seems that you have to create a alternative std something like using cfg to add some āadditionalā parts for capabilities wonāt work as some of the syscallās std uses are not available.
The most simple example is open, the variation of open in CoudABI is very similar to the openat system call, except that the mode parameter takes a different struct which does some more then what the mode parameter in linux open/openat does.
But then I think rust, at some point, needs support for alternative stable stdās anyway. At last if rust wants to take over micro-controllers (!= microprocessors).