xv6-Modified

The goal of this project is to modify the xv6 Operating System by adding new features and functionalities like new keyboard shortcuts for console, new system calls, CPU scheduling, and synchronization.

Phase 1 (Introduction to xv6)

• Add names of contributors to message boot

• Add three new keyboard shortcuts to xv6 shell:

  • CTRL + T: Swap the last two letters before the cursor
  • CTRL + O: Uppercase all letters after the marker
  • CTRL + A: Change the position of the cursor to the beginning of the line

• Design and implementation of a user-level program (factor)

Phase 2 (System calls)

• calculate_sum_of_digits (int num): returns the sum value of all digits in num
• get_file_sectors(int fd): prints the block number on disk for each block of the file
• get_parent_id(void): prints the parent process id of the currently running process
• set_process_parent(int pid): sets the currently running process as the parent of input process (pid)

Phase 3 (CPU Scheduling)

• In this scheduler, processes are placed in different levels according to their priority, which is assumed in this project that there are three levels and subsequently three priorities:
  • Level 1: Round Robin (RR)
  • Level 2: Last Come First Serve (LCFS)
  • Level 3: Modified Highest Response Ratio Next (MHRRN)
• Required system calls:
  • change_queue(int pid, int queue)
  • set_process_MHRRN(int pid, int MHRRN_priority)
  • set_system_MHRRN(int MHRRN_priority)
  • print_info(void)

Phase 4 (Synchronization)

• Implement Counting Semaphore with required system calls:
  • sem_init(int i, int v, int init)
  • sem_acquire(int i)
  • sem_release(int i)
• Simulate Dining Philosophers problem with 5 philosophers by using a monitor

Phase 5 (Memory management)

Implement a POSIX-compliant Unix system call called mmap that maps files or devices into memory. It is a method of memory-mapped file I/O. Required system calls:

• get_free_pages_count()
• mmap(void* addr, size_t length, int prot, int flags, int fd, int offset)

Contributors: Parnian Fazel, Ali Akhgari