Unformatted text preview: hardware directly? Explain exactly it works? The program would attempt to execute a privileged I/O instruction while the mode bit is set to user mode. This generates an error interrupt on the user program and does not even execute the I/O instruction. 5. For API calls to the OS, describe the two major approaches that can be used to physically support message exchanges between processes. (in terms of memory mapping and message buffers and not the identity of the processes or messages involved) Shared memory – the processes have a message buffer in a shared global data area Message Passing – the OS copies the message from the sending process and passes it to the receiving process. (See page 74 and chapter 3 slides)...
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- Fall '08
- Operating Systems, Central processing unit, Computer multitasking, I/O Instruction, privileged I/O instruction