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School of Computer Science & Engineering
University of New South Wales
 Advanced Operating Systems 
 COMP9242 2002/S2 

OS Structure

• OS server is chief of client processes.
• Client's ``system calls'' are library stubs performing RPC to OS server.
• ``OS'' may consist of many server threads in same or separate tasks.
• OS server may redirect client requests to other servers
  • within OS server task,
  • outside OS server task.
• Clans & chiefs mechanism:
  • prevents direct client access to servers running as separate tasks,
  • supports easy redirection of ``system call'' RPC.