CS460 LAB Assignment #6
                   DUE: 11-9-2023
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1. fork-exec as in Unix/Linux
      
1.1. Base code: YOUR LAB5, which supports USER mode commands
     [ps chname switch kfork wait exit]
	   
2.2. Modify commands to
     [ps chname switch wait exit fork exec]

     Implement fork(), exec() in kernel as in Chapter 7.7.6-7.7.7,
	     
NOTE 1: Process User mode images are SAME as in YOUR LAB5
NOTE 2: exec [u1 or u2] argv1 argv2 ,... argvn
        execution of new image must show argc, argv[]	     
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2. Dynamic 2-level Paging as in Chapter 7.9.3.
   Each Umode image size = 4MB;
   Each 1MB area has 256 4KB page frames, which are dynamically allocated
	     
   you may need samples/LAB6/load.O
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