main.c

一个简单的操作系统minix的核心代码

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				src/mm/main.c	 	 
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16600	/* This file contains the main program of the memory manager and some related
16601	 * procedures.  When MINIX starts up, the kernel runs for a little while,
16602	 * initializing itself and its tasks, and then it runs MM and FS.  Both MM
16603	 * and FS initialize themselves as far as they can.  FS then makes a call to
16604	 * MM, because MM has to wait for FS to acquire a RAM disk.  MM asks the
16605	 * kernel for all free memory and starts serving requests.
16606	 *
16607	 * The entry points into this file are:
16608	 *   main:      starts MM running
16609	 *   reply:     reply to a process making an MM system call
16610	 */
16611	
16612	#include "mm.h"
16613	#include <minix/callnr.h>
16614	#include <minix/com.h>
16615	#include <signal.h>
16616	#include <fcntl.h>
16617	#include <sys/ioctl.h>
16618	#include "mproc.h"
16619	#include "param.h"
16620	
16621	FORWARD _PROTOTYPE( void get_work, (void)                               );
16622	FORWARD _PROTOTYPE( void mm_init, (void)                                );
16623	
16624	/*===========================================================================*
16625	 *                              main                                         *
16626	 *===========================================================================*/
16627	PUBLIC void main()
16628	{
16629	/* Main routine of the memory manager. */
16630	
16631	  int error;
16632	
16633	  mm_init();                    /* initialize memory manager tables */
16634	
16635	  /* This is MM's main loop-  get work and do it, forever and forever. */
16636	  while (TRUE) {
16637	        /* Wait for message. */
16638	        get_work();             /* wait for an MM system call */
16639	        mp = &mproc[who];
16640	
16641	        /* Set some flags. */
16642	        error = OK;
16643	        dont_reply = FALSE;
16644	        err_code = -999;
16645	
16646	        /* If the call number is valid, perform the call. */
16647	        if (mm_call < 0 || mm_call >= NCALLS)
16648	                error = EBADCALL;
16649	        else
16650	                error = (*call_vec[mm_call])();
16651	
16652	        /* Send the results back to the user to indicate completion. */
16653	        if (dont_reply) continue;       /* no reply for EXIT and WAIT */
16654	        if (mm_call == EXEC && error == OK) continue;
16655	        reply(who, error, result2, res_ptr);
16656	  }
16657	}
	
	
16660	/*===========================================================================*
16661	 *                              get_work                                     *
16662	 *===========================================================================*/
16663	PRIVATE void get_work()
16664	{
16665	/* Wait for the next message and extract useful information from it. */
16666	
16667	  if (receive(ANY, &mm_in) != OK) panic("MM receive error", NO_NUM);
16668	  who = mm_in.m_source;         /* who sent the message */
16669	  mm_call = mm_in.m_type;       /* system call number */
16670	}
	
	
16673	/*===========================================================================*
16674	 *                              reply                                        *
16675	 *===========================================================================*/
16676	PUBLIC void reply(proc_nr, result, res2, respt)
16677	int proc_nr;                    /* process to reply to */
16678	int result;                     /* result of the call (usually OK or error #)*/
16679	int res2;                       /* secondary result */
16680	char *respt;                    /* result if pointer */
16681	{
16682	/* Send a reply to a user process. */
16683	
16684	  register struct mproc *proc_ptr;
16685	
16686	  proc_ptr = &mproc[proc_nr];
16687	  /* 
16688	   * To make MM robust, check to see if destination is still alive.  This
16689	   * validy check must be skipped if the caller is a task.
16690	   */
16691	  if ((who >=0) && ((proc_ptr->mp_flags&IN_USE) == 0 || 
16692	        (proc_ptr->mp_flags&HANGING))) return;
16693	
16694	  reply_type = result;
16695	  reply_i1 = res2;
16696	  reply_p1 = respt;
16697	  if (send(proc_nr, &mm_out) != OK) panic("MM can't reply", NO_NUM);
16698	}
	
	
16701	/*===========================================================================*
16702	 *                              mm_init                                      *
16703	 *===========================================================================*/
16704	PRIVATE void mm_init()
16705	{
16706	/* Initialize the memory manager. */
16707	
16708	  static char core_sigs[] = {
16709	        SIGQUIT, SIGILL, SIGTRAP, SIGABRT,
16710	        SIGEMT, SIGFPE, SIGUSR1, SIGSEGV,
16711	        SIGUSR2, 0 };
16712	  register int proc_nr;
16713	  register struct mproc *rmp;
16714	  register char *sig_ptr;
16715	  phys_clicks ram_clicks, total_clicks, minix_clicks, free_clicks, dummy;
16716	  message mess;
16717	  struct mem_map kernel_map[NR_SEGS];
16718	  int mem;
16719	
16720	  /* Build the set of signals which cause core dumps. Do it the Posix
16721	   * way, so no knowledge of bit positions is needed.
16722	   */
16723	  sigemptyset(&core_sset);
16724	  for (sig_ptr = core_sigs; *sig_ptr != 0; sig_ptr++)
16725	        sigaddset(&core_sset, *sig_ptr);
16726	
16727	  /* Get the memory map of the kernel to see how much memory it uses,
16728	   * including the gap between address 0 and the start of the kernel.
16729	   */
16730	  sys_getmap(SYSTASK, kernel_map);
16731	  minix_clicks = kernel_map[S].mem_phys + kernel_map[S].mem_len;
16732	
16733	  /* Initialize MM's tables. */
16734	  for (proc_nr = 0; proc_nr <= INIT_PROC_NR; proc_nr++) {
16735	        rmp = &mproc[proc_nr];
16736	        rmp->mp_flags |= IN_USE;
16737	        sys_getmap(proc_nr, rmp->mp_seg);
16738	        if (rmp->mp_seg[T].mem_len != 0) rmp->mp_flags |= SEPARATE;
16739	        minix_clicks += (rmp->mp_seg[S].mem_phys + rmp->mp_seg[S].mem_len)
16740	                                - rmp->mp_seg[T].mem_phys;
16741	  }
16742	  mproc[INIT_PROC_NR].mp_pid = INIT_PID;
16743	  sigemptyset(&mproc[INIT_PROC_NR].mp_ignore);
16744	  sigemptyset(&mproc[INIT_PROC_NR].mp_catch);
16745	  procs_in_use = LOW_USER + 1;
16746	
16747	  /* Wait for FS to send a message telling the RAM disk size then go "on-line".
16748	   */
16749	  if (receive(FS_PROC_NR, &mess) != OK)
16750	        panic("MM can't obtain RAM disk size from FS", NO_NUM);
16751	
16752	  ram_clicks = mess.m1_i1;
16753	
16754	  /* Initialize tables to all physical mem. */
16755	  mem_init(&total_clicks, &free_clicks);
16756	
16757	  /* Print memory information. */
16758	  printf("\nMemory size =%5dK   ", click_to_round_k(total_clicks));
16759	  printf("MINIX =%4dK   ", click_to_round_k(minix_clicks));
16760	  printf("RAM disk =%5dK   ", click_to_round_k(ram_clicks));
16761	  printf("Available =%5dK\n\n", click_to_round_k(free_clicks));
16762	
16763	  /* Tell FS to continue. */
16764	  if (send(FS_PROC_NR, &mess) != OK)
16765	        panic("MM can't sync up with FS", NO_NUM);
16766	
16767	  /* Tell the memory task where my process table is for the sake of ps(1). */
16768	  if ((mem = open("/dev/mem", O_RDWR)) != -1) {
16769	        ioctl(mem, MIOCSPSINFO, (void *) mproc);
16770	        close(mem);
16771	  }
16772	}