| rax | 7 | wait for process termination | 8 bit |
| rbx | pid | process identification | 32 bit (pid_t) |
| <-1 | wait for any child process whose process group ID is equal to the absolute value of pid. | ||
| -1 | wait for any child process; this is the same behaviour which wait exhibits. | ||
| 0 | wait for any child process whose process group ID is equal to that of the calling process. | ||
| >0 | wait for the child whose process ID is equal to the value of pid. | ||
| rcx | *status | Pointer | 16 bit |
| rdx | options | System options | 32 bit |
| On return | rax | |
| Child PID | on success. | |
| 0 | if WNOHANG was used and no child was available. |
| Errorcode | c++ name | Description |
| 4 | EINTR | if WNOHANG was not set and an unblocked signal or a SIGCHLD was caught. |
| 10 | ECHILD | if the process specified in pid does not exist or is not a child of the calling process. |
| 22 | EINVAL | if the options argument was invalid. |