It's interesting that the v4 code linked reuses pid 0 (the code that assigns pids simply does "p->p_pid = ++mpid;") - I vaguely remember having to fix that in k

It's interesting that the v4 code linked reuses pid 0 (the code that assigns pids simply does "p->p_pid = ++mpid;") - I vaguely remember having to fix that in kernels we were working on in the mid 80s