main.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

void calibrate_delay(void)
{
	int ticks;
	int loopbit;
	int lps_precision = LPS_PREC;

	loops_per_sec = (1<<12);

	printk("Calibrating delay loop.. ");
	while (loops_per_sec <<= 1) {
		/* wait for "start of" clock tick */
		ticks = jiffies;
		while (ticks == jiffies)
			/* nothing */;
		/* Go .. */
		ticks = jiffies;
		__delay(loops_per_sec);
		ticks = jiffies - ticks;
		if (ticks)
			break;
		}

/* Do a binary approximation to get loops_per_second set to equal one clock
   (up to lps_precision bits) */
	loops_per_sec >>= 1;
	loopbit = loops_per_sec;
	while ( lps_precision-- && (loopbit >>= 1) ) {
		loops_per_sec |= loopbit;
		ticks = jiffies;
		while (ticks == jiffies);
		ticks = jiffies;
		__delay(loops_per_sec);
		if (jiffies != ticks)	/* longer than 1 tick */
			loops_per_sec &= ~loopbit;
	}

/* finally, adjust loops per second in terms of seconds instead of clocks */	
	loops_per_sec *= HZ;
/* Round the value and print it */	
	printk("ok - %lu.%02lu BogoMIPS\n",
		(loops_per_sec+2500)/500000,
		((loops_per_sec+2500)/5000) % 100);

#if defined(__SMP__) && defined(__i386__)
	smp_loops_per_tick = loops_per_sec / 400;
#endif
}

static void parse_root_dev(char * line)
{
	int base = 0;
	static struct dev_name_struct {
		const char *name;
		const int num;
	} devices[] = {
		{ "nfs",     0x00ff },
		{ "loop",    0x0700 },
		{ "hda",     0x0300 },
		{ "hdb",     0x0340 },
		{ "hdc",     0x1600 },
		{ "hdd",     0x1640 },
		{ "hde",     0x2100 },
		{ "hdf",     0x2140 },
		{ "hdg",     0x2200 },
		{ "hdh",     0x2240 },
		{ "sda",     0x0800 },
		{ "sdb",     0x0810 },
		{ "sdc",     0x0820 },
		{ "sdd",     0x0830 },
		{ "sde",     0x0840 },
		{ "sdf",     0x0850 },
		{ "sdg",     0x0860 },
		{ "sdh",     0x0870 },
		{ "sdi",     0x0880 },
		{ "sdj",     0x0890 },
		{ "sdk",     0x08a0 },
		{ "sdl",     0x08b0 },
		{ "sdm",     0x08c0 },
		{ "sdn",     0x08d0 },
		{ "sdo",     0x08e0 },
		{ "sdp",     0x08f0 },
		{ "fd",      0x0200 },
		{ "xda",     0x0d00 },
		{ "xdb",     0x0d40 },
		{ "ram",     0x0100 },
		{ "scd",     0x0b00 },
		{ "mcd",     0x1700 },
		{ "cdu535",  0x1800 },
		{ "aztcd",   0x1d00 },
		{ "cm206cd", 0x2000 },
		{ "gscd",    0x1000 },
		{ "sbpcd",   0x1900 },
		{ "sonycd",  0x1800 },
#ifdef CONFIG_PARIDE_PD
       		{ "pda",     0x2d00 },
       		{ "pdb",     0x2d10 },
       		{ "pdc",     0x2d20 },
       		{ "pdd",     0x2d30 },
#endif
#ifdef CONFIG_PARIDE_PCD
     	  	{ "pcd",     0x2e00 },
#endif
#ifdef CONFIG_PARIDE_PF
	       	{ "pf",      0x2f00 },
#endif
		{ NULL, 0 }
	};

	if (strncmp(line,"/dev/",5) == 0) {
		struct dev_name_struct *dev = devices;
		line += 5;
		do {
			int len = strlen(dev->name);
			if (strncmp(line,dev->name,len) == 0) {
				line += len;
				base = dev->num;
				break;
			}
			dev++;
		} while (dev->name);
	}
	ROOT_DEV = to_kdev_t(base + simple_strtoul(line,NULL,base?10:16));
}

/*
 * This is a simple kernel command line parsing function: it parses
 * the command line, and fills in the arguments/environment to init
 * as appropriate. Any cmd-line option is taken to be an environment
 * variable if it contains the character '='.
 *
 *
 * This routine also checks for options meant for the kernel.
 * These options are not given to init - they are for internal kernel use only.
 */
static void parse_options(char *line)
{
	char *next;
	int args, envs;

	if (!*line)
		return;
	args = 0;
	envs = 1;	/* TERM is set to 'linux' by default */
	next = line;
	while ((line = next) != NULL) {
		if ((next = strchr(line,' ')) != NULL)
			*next++ = 0;
		/*
		 * check for kernel options first..
		 */
		if (!strncmp(line,"root=",5)) {
			parse_root_dev(line+5);
			continue;
		}
#ifdef CONFIG_ROOT_NFS
		if (!strncmp(line, "nfsroot=", 8)) {
			int n;
			line += 8;
			ROOT_DEV = MKDEV(UNNAMED_MAJOR, 255);
			if (line[0] == '/' || line[0] == ',' || (line[0] >= '0' && line[0] <= '9')) {
				strncpy(nfs_root_name, line, sizeof(nfs_root_name));
				nfs_root_name[sizeof(nfs_root_name)-1] = '\0';
				continue;
			}
			n = strlen(line) + strlen(NFS_ROOT);
			if (n >= sizeof(nfs_root_name))
				line[sizeof(nfs_root_name) - strlen(NFS_ROOT) - 1] = '\0';
			sprintf(nfs_root_name, NFS_ROOT, line);
			continue;
		}
		if (!strncmp(line, "nfsaddrs=", 9)) {
			line += 9;
			strncpy(nfs_root_addrs, line, sizeof(nfs_root_addrs));
			nfs_root_addrs[sizeof(nfs_root_addrs)-1] = '\0';
			continue;
		}
#endif
		if (!strcmp(line,"ro")) {
			root_mountflags |= MS_RDONLY;
			continue;
		}
		if (!strcmp(line,"rw")) {
			root_mountflags &= ~MS_RDONLY;
			continue;
		}
		if (!strcmp(line,"debug")) {
			console_loglevel = 10;
			continue;
		}
		if (!strncmp(line,"init=",5)) {
			line += 5;
			execute_command = line;
			continue;
		}
		if (checksetup(line))
			continue;
		/*
		 * Then check if it's an environment variable or
		 * an option.
		 */
		if (strchr(line,'=')) {
			if (envs >= MAX_INIT_ENVS)
				break;
			envp_init[++envs] = line;
		} else {
			if (args >= MAX_INIT_ARGS)
				break;
			argv_init[++args] = line;
		}
	}
	argv_init[args+1] = NULL;
	envp_init[envs+1] = NULL;
}


extern void setup_arch(char **, unsigned long *, unsigned long *);
extern void arch_syms_export(void);

#ifndef __SMP__

/*
 *	Uniprocessor idle thread
 */
 
int cpu_idle(void *unused)
{
	for(;;)
		idle();
}

#else

/*
 *	Multiprocessor idle thread is in arch/...
 */
 
extern int cpu_idle(void * unused);

/*
 *	Activate a secondary processor.
 */
 
asmlinkage void start_secondary(void)
{
	trap_init();
	init_IRQ();
	smp_callin();
	cpu_idle(NULL);
}



/*
 *	Called by CPU#0 to activate the rest.
 */
 
static void smp_init(void)
{
	int i, j;
	smp_boot_cpus();
	
	/*
	 *	Create the slave init tasks as sharing pid 0.
	 *
	 *	This should only happen if we have virtual CPU numbers
	 *	higher than 0.
	 */

	for (i=1; i<smp_num_cpus; i++)
	{
		struct task_struct *n, *p;

		j = cpu_logical_map[i];
		/*
		 *	We use kernel_thread for the idlers which are
		 *	unlocked tasks running in kernel space.
		 */
		kernel_thread(cpu_idle, NULL, CLONE_PID);
		/*
		 *	Don't assume linear processor numbering
		 */
		current_set[j]=task[i];
		current_set[j]->processor=j;
		cli();
		n = task[i]->next_run;
		p = task[i]->prev_run;
		nr_running--;
		n->prev_run = p;
		p->next_run = n;
		task[i]->next_run = task[i]->prev_run = task[i];
		sti();
	}
}		

/*
 *	The autoprobe routines assume CPU#0 on the i386
 *	so we don't actually set the game in motion until
 *	they are finished.
 */
 
static void smp_begin(void)
{
	smp_threads_ready=1;
	smp_commence();
}
	
#endif

/*
 *	Activate the first processor.
 */
 
asmlinkage void start_kernel(void)
{
	char * command_line;

/*
 *	This little check will move.
 */

#ifdef __SMP__
	static int first_cpu=1;
	
	if(!first_cpu)
		start_secondary();
	first_cpu=0;
	
#endif	
/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
	setup_arch(&command_line, &memory_start, &memory_end);
	memory_start = paging_init(memory_start,memory_end);
	trap_init();
	init_IRQ();
	sched_init();
	time_init();
	parse_options(command_line);
#ifdef CONFIG_MODULES
	init_modules();
#endif
#ifdef CONFIG_PROFILE
	if (!prof_shift)
#ifdef CONFIG_PROFILE_SHIFT
		prof_shift = CONFIG_PROFILE_SHIFT;
#else
		prof_shift = 2;
#endif
#endif
	if (prof_shift) {
		prof_buffer = (unsigned int *) memory_start;
		/* only text is profiled */
		prof_len = (unsigned long) &_etext - (unsigned long) &_stext;
		prof_len >>= prof_shift;
		memory_start += prof_len * sizeof(unsigned int);
		memset(prof_buffer, 0, prof_len * sizeof(unsigned int));
	}
	memory_start = console_init(memory_start,memory_end);
#ifdef CONFIG_PCI
	memory_start = pci_init(memory_start,memory_end);
#endif
	memory_start = kmalloc_init(memory_start,memory_end);
	sti();
	calibrate_delay();
	memory_start = inode_init(memory_start,memory_end);
	memory_start = file_table_init(memory_start,memory_end);
	memory_start = name_cache_init(memory_start,memory_end);
#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_start && initrd_start < memory_start) {
		printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
		    "disabling it.\n",initrd_start,memory_start);
		initrd_start = 0;
	}
#endif
	mem_init(memory_start,memory_end);
	buffer_init();
	sock_init();
#if defined(CONFIG_SYSVIPC) || defined(CONFIG_KERNELD)
	ipc_init();
#endif
	dquot_init();
	arch_syms_export();
	sti();
	check_bugs();

#if defined(CONFIG_MTRR) && defined(__SMP__)
	init_mtrr_config();
#endif


	printk(linux_banner);
#ifdef __SMP__
	smp_init();
#endif
	sysctl_init();
	/* 
	 *	We count on the initial thread going ok 
	 *	Like idlers init is an unlocked kernel thread, which will
	 *	make syscalls (and thus be locked).
	 */
	kernel_thread(init, NULL, 0);
/*
 * task[0] is meant to be used as an "idle" task: it may not sleep, but
 * it might do some general things like count free pages or it could be
 * used to implement a reasonable LRU algorithm for the paging routines:
 * anything that can be useful, but shouldn't take time from the real
 * processes.
 *
 * Right now task[0] just does a infinite idle loop.
 */
 	cpu_idle(NULL);
}

static int printf(const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	write(1,printbuf,i=vsprintf(printbuf, fmt, args));
	va_end(args);
	return i;
}

static int do_rc(void * rc)
{
	close(0);
	if (open(rc,O_RDONLY,0))
		return -1;
	return execve("/bin/sh", argv_rc, envp_rc);
}

static int do_shell(void * shell)
{
	close(0);close(1);close(2);
	setsid();
	(void) open("/dev/tty1",O_RDWR,0);
	(void) dup(0);
	(void) dup(0);
	return execve(shell, argv, envp);
}

#ifdef CONFIG_BLK_DEV_INITRD
static int do_linuxrc(void * shell)
{
	static char *argv[] = { "linuxrc", NULL, };

	close(0);close(1);close(2);
	setsid();
	(void) open("/dev/tty1",O_RDWR,0);
	(void) dup(0);
	(void) dup(0);
	return execve(shell, argv, envp_init);
}

static void no_initrd(char *s,int *ints)
{
	mount_initrd = 0;
}
#endif

static int init(void * unused)
{
	int pid,i;
#ifdef CONFIG_BLK_DEV_INITRD
	int real_root_mountflags;
#endif

	/* Launch bdflush from here, instead of the old syscall way. */
	kernel_thread(bdflush, NULL, 0);
	/* Start the background pageout daemon. */
	kswapd_setup();
	kernel_thread(kswapd, NULL, 0);

#ifdef CONFIG_BLK_DEV_INITRD
	real_root_dev = ROOT_DEV;
	real_root_mountflags = root_mountflags;
	if (initrd_start && mount_initrd) root_mountflags &= ~MS_RDONLY;
	else mount_initrd =0;
#endif
	setup();

#ifdef __SMP__
	/*
	 *	With the devices probed and setup we can
	 *	now enter SMP mode.
	 */
	
	smp_begin();
#endif	

	#ifdef CONFIG_UMSDOS_FS
	{
		/*
			When mounting a umsdos fs as root, we detect
			the pseudo_root (/linux) and initialise it here.
			pseudo_root is defined in fs/umsdos/inode.c
		*/
		extern struct inode *pseudo_root;
		if (pseudo_root != NULL){
			current->fs->root = pseudo_root;
			current->fs->pwd  = pseudo_root;
		}
	}
	#endif

#ifdef CONFIG_BLK_DEV_INITRD
	root_mountflags = real_root_mountflags;
	if (mount_initrd && ROOT_DEV != real_root_dev && ROOT_DEV == MKDEV(RAMDISK_MAJOR,0)) {
		int error;

		pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
		if (pid>0)
			while (pid != wait(&i));
		if (real_root_dev != MKDEV(RAMDISK_MAJOR, 0)) {
			error = change_root(real_root_dev,"/initrd");
			if (error)
				printk(KERN_ERR "Change root to /initrd: "
				    "error %d\n",error);
		}
	}
#endif
	
	/*
	 *	This keeps serial console MUCH cleaner, but does assume
	 *	the console driver checks there really is a video device
	 *	attached (Sparc effectively does).
	 */

	if ((open("/dev/tty1",O_RDWR,0) < 0) &&
	    (open("/dev/ttyS0",O_RDWR,0) < 0))
		printk("Unable to open an initial console.\n");
			
	(void) dup(0);
	(void) dup(0);

	if (!execute_command) {
		execve("/etc/init",argv_init,envp_init);
		execve("/bin/init",argv_init,envp_init);
		execve("/sbin/init",argv_init,envp_init);
		/* if this fails, fall through to original stuff */

		pid = kernel_thread(do_rc, "/etc/rc", SIGCHLD);
		if (pid>0)
			while (pid != wait(&i))
				/* nothing */;
	}

	while (1) {
		pid = kernel_thread(do_shell,
			execute_command ? execute_command : "/bin/sh",
			SIGCHLD);
		if (pid < 0) {
			printf("Fork failed in init\n\r");
			continue;
		}
		while (1)
			if (pid == wait(&i))
				break;
		printf("\n\rchild %d died with code %04x\n\r",pid,i);
		sync();
	}
	return -1;
}