Some notes on xv6 OS modifications for my class.

• user.h - function prototype
• usys.S - list of system calls (no preprocessor directives)
• syscall.h - mappings for system call name to number (no preprocessor directives)
• syscall.c - system call entry point, function definition in function dispatch table
• sysproc.c - implement sys_function()

• uint getuid(void)
• uint getgid(void)
• uint getppid(void)
• int setuid(uint)
• int setgid(uint)

• user.h - added get/set uid/gid
  • added getprocs()
• usys.S - added system calls
• syscall.h - added mappings for system call name to number
• syscall.c - added system call entry points and function definitions in function dispatch table
• sysproc.c - implemented functions
• param.h - added define for INIT_PPID
• proc.h - added uid, gid, ppid to struct proc / added cpu_ticks_total and cpu_ticks_in variables to struct proc
• proc.c
  • set default values for uid, gid, ppid, and set ppid of new process in fork().
  • update scheduler(), yield() and sleep() to keep track of process ticks.
  • create helper functions to print ctrl-P info
• sh.c - enabled get/set shell commands
• runoff.list - added gid/uid, uproc.h
• ps.c - implemented ps