-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]
          [,spawn=allow|deny][,resourcecontrol=allow|deny]
                Enable seccomp mode 2 system call filter (default 'off').
                use 'obsolete' to allow obsolete system calls that are provided
                    by the kernel, but typically no longer used by modern
                    C library implementations.
                use 'elevateprivileges' to allow or deny QEMU process to elevate
                    its privileges by blacklisting all set*uid|gid system calls.
                    The value 'children' will deny set*uid|gid system calls for
                    main QEMU process but will allow forks and execves to run unprivileged
                use 'spawn' to avoid QEMU to spawn new threads or processes by
                     blacklisting *fork and execve
                use 'resourcecontrol' to disable process affinity and schedular priority