the master device port and the privileged host port in subhurd

[zhengda]

Hello,

When I look into the code of servers in Hurd, I find almost every server 
calls get_privileged_ports() to get the master device port and the 
privileged host port.
and get_privileged_ports() seems to invoke a system call of mach.
If servers run in subhurd, do they get the same port as they run in the 
main Hurd?
Normally, it should be.
But if it is, how the servers in subhurd are isolated with the ones in 
the main Hurd?
From the eyes of Mach, there are only servers. Mach doesn't know a 
server belongs to the main Hurd or subhurd, right?
Then how does the progress running in the subhurd find the right server 
(the one in the subhurd)?

Best,
Zheng Da