In which cases would it be impossible for user level programs to provide these s

Question

In which cases would it be impossible for user level programs to provide these services? Explain

a.Program execution = the system must be able to load a program into memory and to run that program. The program must be able to end its execution, either normally or abnormally.
b.I/O operations = a running program may require I/O, which may involve a file or an I/O device. For efficiency and protection, users usually cannot control I/O devices directly.
c.File-system manipulation = is of particular interest. Programs need to read and write files and directories. They also need to create and delete them by name, search for a file, and list file information. Finally, some programs include permissions management to allow or deny access to files or directories based on file ownership.
d.Communications = may be implemented via shared memory, or by message
passing, in which packets of information are moved between processes by the operating system.
e.Error detection = occurs at both the hardware and software levels. The operating
system should take the appropriate action to ensure correct and consistent computing.

Explanation / Answer

Program execution:

This is not possible to provide program execution through user level programs because handling hardware, allocating CPU time, handling resources and program execution are difficult for a user and cannot be done properly.

I/O operations:

These services cannot be provided by user level programs because I/O operations cannot be done by their own by a user without system intervention. They can only be done to some extent by a user and the system has to perform the device operations.

File-system manipulation:

This service can be provided its best by an operating system rather than the user level programs. File system manipulation involves allocating and deallocating memory on file creation and deletion etc. a user may not perform the memory allocations perfectly.

Communication:

As the communication between processes involves exchange of messages and packets, it needs the network involvement. As a user will not have access to network devices and exchange of network messages, user level programs cannot provide this service.

Error detection:

Only some specified services at lower level can only be provided by user level programs. Some errors like running out of memory, errors due to storage etc cannot be handled by a user. They need OS involvement.

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