text: /* See COPYRIGHT for copyright information. */
  
  #include <inc/stdio.h>
  #include <inc/string.h>
  #include <inc/assert.h>
  
  #include <kern/monitor.h>
  #include <kern/console.h>
  #include <kern/pmap.h>
  #include <kern/kclock.h>
  #include <kern/env.h>
  #include <kern/trap.h>
  
  
  // Test the stack backtrace function (lab 1 only)
  /*
  void
  test_backtrace(int x)
  {
  	cprintf("entering test_backtrace %d\n", x);
  	if (x > 0)
  		test_backtrace(x-1);
  	else
  		mon_backtrace(0, 0, 0);
  	cprintf("leaving test_backtrace %d\n", x);
  }
  */
  
  void
  i386_init(void)
  {
  	extern char edata[], end[];
  
  	// Before doing anything else, complete the ELF loading process.
  	// Clear the uninitialized global data (BSS) section of our program.
  	// This ensures that all static/global variables start out zero.
  	memset(edata, 0, end - edata);
  
  	// Initialize the console.
  	// Can't call cprintf until after we do this!
  	cons_init();
  
  	cprintf("6828 decimal is %o octal!\n", 6828);
  
  	// Lab 2 memory management initialization functions
  	mem_init();
  
  	// Lab 3 user environment initialization functions
  	env_init();
  	trap_init();
  
  #if defined(TEST)
  	// Don't touch -- used by grading script!
  	ENV_CREATE(TEST, ENV_TYPE_USER);
  #else
  	// Touch all you want.
  	ENV_CREATE(user_hello, ENV_TYPE_USER);
  #endif // TEST*
  
  	// We only have one user environment for now, so just run it.
  	env_run(&envs[0]);
  }
  
  
  /*
   * Variable panicstr contains argument to first call to panic; used as flag
   * to indicate that the kernel has already called panic.
   */
  const char *panicstr;
  
  /*
   * Panic is called on unresolvable fatal errors.
   * It prints "panic: mesg", and then enters the kernel monitor.
   */
  void
  _panic(const char *file, int line, const char *fmt,...)
  {
  	va_list ap;
  
  	if (panicstr)
  		goto dead;
  	panicstr = fmt;
  
  	// Be extra sure that the machine is in as reasonable state
  	asm volatile("cli; cld");
  
  	va_start(ap, fmt);
  	cprintf("kernel panic at %s:%d: ", file, line);
  	vcprintf(fmt, ap);
  	cprintf("\n");
  	va_end(ap);
  
  dead:
  	/* break into the kernel monitor */
  	while (1)
  		monitor(NULL);
  }
  
  /* like panic, but don't */
  void
  _warn(const char *file, int line, const char *fmt,...)
  {
  	va_list ap;
  
  	va_start(ap, fmt);
  	cprintf("kernel warning at %s:%d: ", file, line);
  	vcprintf(fmt, ap);
  	cprintf("\n");
  	va_end(ap);
  }
  