The global zone acts as both the default zone for the system and as a zone for system-wide administrative control. There are administrative issues associated with this dual role. Since applications within the zone have access to processes and other system objects in other zones, the effect of administrative actions can be wider than expected. For example, service shutdown scripts often use pkill to signal processes of a given name to exit. When such a script is run from the global zone, all such processes in the system will be signaled, regardless of zone.
The system-wide scope is often needed. For example, to monitor system-wide resource usage, you must view process statistics for the whole system. A view of just global zone activity would miss relevant information from other zones in the system that might be sharing some or all of the system resources. Such a view is particularly important when system resources such as CPU are not strictly partitioned using resource management facilities.
Thus, processes in the global zone can observe processes and other objects in non-global zones. This allows such processes to have system-wide observability. The ability to control or send signals to processes in other zones is restricted by the privilege PRIV_PROC_ZONE. The privilege is similar to PRIV_PROC_OWNER because the privilege allows processes to override the restrictions placed on unprivileged processes. In this case, the restriction is that unprivileged processes in the global zone cannot signal or control processes in other zones. This is true even when the user IDs of the processes match or the acting process has the PRIV_PROC_OWNER privilege. The PRIV_PROC_ZONE privilege can be removed from otherwise privileged processes to restrict actions to the global zone.