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Implementing new Minix System Calls

What is required to add a new system call to Minix?

First, there are several system "processes", including the server processes - process manager (pm) and file system process (vfs) as well as the idle, clock, system, and kernel processes.

If you execute the command ps -ef | more, you can see that the last four are listed with negative PID's and pm has pid 0 in Minix.

A user cannot directly make a system call to the kernel or system (except for the message passing function _syscall).

So implementing a new system call available to a user must start with sending a message to a server process.



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