UNIX Programming and Technical

Q. What do you mean by u-area (user area) or u-block?

A. This contains the private data that is manipulated only by the Kernel. This is local to the Process, i.e. each process is allocated a u-area.

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UNIX Other Question

Q. Is the Process before and after the swap are the same? Give reason.

A. Process before swapping is residing in the primary memory in its original form. The regions (text, data and stack) may not be occupied fully by the process, there may be few empty slots in any of the regions and while swapping Kernel do not bother about the empty slots while swapping the process out.
After swapping the process resides in the swap (secondary memory) device. The regions swapped out will be present but only the occupied region slots but not the empty slots that were present before assigning.
While swapping the process once again into the main memory, the Kernel referring to the Process Memory Map, it assigns the main memory accordingly taking care of the empty slots in the regions. Q. What are the entities that are swapped out of the main memory while swapping the process out of the main memory?

A. All memory space occupied by the process, process's u-area, and Kernel stack are swapped out, theoretically. Practically, if the process's u-area contains the Address Translation Tables for the process then Kernel implementations do not swap the u-area.