main.c,v

powerpc内核mpc8241linux系统下init驱动程序

static int __init checksetup(char *line)
{
	int i, ints[11];

#ifdef CONFIG_BLK_DEV_IDE
	/* ide driver needs the basic string, rather than pre-processed values */
	if (!strncmp(line,"ide",3) || (!strncmp(line,"hd",2) && line[2] != '=')) {
		ide_setup(line);
		return 1;
	}
#endif
	for (i=0; raw_params[i].str; i++) {
		int n = strlen(raw_params[i].str);
		if (!strncmp(line,raw_params[i].str,n)) {
			raw_params[i].setup_func(line+n, NULL);
			return 1;
		}
	}
	for (i=0; cooked_params[i].str; i++) {
		int n = strlen(cooked_params[i].str);
		if (!strncmp(line,cooked_params[i].str,n)) {
			cooked_params[i].setup_func(get_options(line+n, ints), ints);
			return 1;
		}
	}
	return 0;
}

/* this should be approx 2 Bo*oMips to start (note initial shift), and will
   still work even if initially too large, it will just take slightly longer */
unsigned long loops_per_sec = (1<<12);

/* This is the number of bits of precision for the loops_per_second.  Each
   bit takes on average 1.5/HZ seconds.  This (like the original) is a little
   better than 1% */
#define LPS_PREC 8

void __init calibrate_delay(void)
{
	unsigned long ticks, 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("%lu.%02lu BogoMIPS\n",
		(loops_per_sec+2500)/500000,
		((loops_per_sec+2500)/5000) % 100);
}

/*
 * 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 __init 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 (!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;
			/* In case LILO is going to boot us with default command line,
			 * it prepends "auto" before the whole cmdline which makes
			 * the shell think it should execute a script with such name.
			 * So we ignore all arguments entered _before_ init=... [MJ]
			 */
			args = 0;
			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 *);

#ifndef __SMP__

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

#define smp_init()	do { } while (0)

#else

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

/* Called by boot processor to activate the rest. */
static void __init smp_init(void)
{
	/* Get other processors into their bootup holding patterns. */
	smp_boot_cpus();
	smp_threads_ready=1;
	smp_commence();
}		

#endif

extern void initialize_secondary(void);

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

#ifdef __SMP__
	static int boot_cpu = 1;
	/* "current" has been set up, we need to load it now */
	if (!boot_cpu)
		initialize_secondary();
	boot_cpu = 0;
#endif

/*
 * Interrupts are still disabled. Do necessary setups, then
 * enable them
 */
	printk(linux_banner);
	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);

	/*
	 * HACK ALERT! This is early. We're enabling the console before
	 * we've done PCI setups etc, and console_init() must be aware of
	 * this. But we do want output early, in case something goes wrong.
	 */
	memory_start = console_init(memory_start,memory_end);
#ifdef CONFIG_MODULES
	init_modules();
#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 = kmem_cache_init(memory_start, memory_end);
	sti(); 
	calibrate_delay(); 
#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_start && !initrd_below_start_ok && 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);
	kmem_cache_sizes_init();
#ifdef CONFIG_PROC_FS
	proc_root_init();
#endif
	uidcache_init();
	filescache_init();
	dcache_init();
	vma_init();
	buffer_init();
	signals_init();
	inode_init();
	file_table_init();
#if defined(CONFIG_SYSVIPC)
	ipc_init();
#endif
#if defined(CONFIG_QUOTA)
	dquot_init_hash();
#endif
	check_bugs();
	printk("POSIX conformance testing by UNIFIX\n");

	/* 
	 *	We count on the initial thread going ok 
	 *	Like idlers init is an unlocked kernel thread, which will
	 *	make syscalls (and thus be locked).
	 */
	smp_init();
	kernel_thread(init, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
	current->need_resched = 1;
 	cpu_idle(NULL);
}

#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/console",O_RDWR,0);
	(void) dup(0);
	(void) dup(0);
	return execve(shell, argv, envp_init);
}

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

struct task_struct *child_reaper = &init_task;

/*
 * Ok, the machine is now initialized. None of the devices
 * have been touched yet, but the CPU subsystem is up and
 * running, and memory and process management works.
 *
 * Now we can finally start doing some real work..
 */
static void __init do_basic_setup(void)
{
#ifdef CONFIG_BLK_DEV_INITRD
	int real_root_mountflags;
#endif

	/*
	 * Tell the world that we're going to be the grim
	 * reaper of innocent orphaned children.
	 *
	 * We don't want people to have to make incorrect
	 * assumptions about where in the task array this
	 * can be found.
	 */
	child_reaper = current;

#if defined(CONFIG_MTRR)	/* Do this after SMP initialization */
/*
 * We should probably create some architecture-dependent "fixup after
 * everything is up" style function where this would belong better
 * than in init/main.c..
 */
	mtrr_init();
#endif

#ifdef CONFIG_SYSCTL
	sysctl_init();
#endif

	/*
	 * Ok, at this point all CPU's should be initialized, so
	 * we can start looking into devices..
	 */
#ifdef CONFIG_PCI
	pci_init();
#endif
#ifdef CONFIG_USB
    usb_init();
#endif
#ifdef CONFIG_SBUS
	sbus_init();
#endif
#if defined(CONFIG_PPC)
	powermac_init();
#endif
#ifdef CONFIG_MCA
	mca_init();
#endif
#ifdef CONFIG_ARCH_ACORN
	ecard_init();
#endif
#ifdef CONFIG_ZORRO
	zorro_init();
#endif
#ifdef CONFIG_DIO
	dio_init();
#endif

	/* Networking initialization needs a process context */ 
	sock_init();

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

#if CONFIG_AP1000
	/* Start the async paging daemon. */
	{
	  extern int asyncd(void *);	 
	  kernel_thread(asyncd, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
	}
#endif
#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

	/* Set up devices .. */
	device_setup();

	/* .. executable formats .. */
	binfmt_setup();

	/* .. filesystems .. */
	filesystem_setup();

	/* Mount the root filesystem.. */
	mount_root();

#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->i_sb->s_root;
			current->fs->pwd  = pseudo_root->i_sb->s_root;
		}
	}
#endif

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

		pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
		if (pid>0)
			while (pid != wait(&i));
		if (MAJOR(real_root_dev) != RAMDISK_MAJOR
		     || MINOR(real_root_dev) != 0) {
			error = change_root(real_root_dev,"/initrd");
			if (error)
				printk(KERN_ERR "Change root to /initrd: "
				    "error %d\n",error);
		}
	}
#endif
}

static int init(void * unused)
{
	lock_kernel();
	do_basic_setup();

	/*
	 * Ok, we have completed the initial bootup, and
	 * we're essentially up and running. Get rid of the
	 * initmem segments and start the user-mode stuff..
	 */
/* 	free_initmem();  */
	unlock_kernel();

	if (open("/dev/console", O_RDWR, 0) < 0)
		printk("Warning: unable to open an initial console.\n");
	(void) dup(0);
	(void) dup(0);
	
	/*
	 * We try each of these until one succeeds.
	 *
	 * The Bourne shell can be used instead of init if we are 
	 * trying to recover a really broken machine.
	 */

	if (execute_command)
		execve(execute_command,argv_init,envp_init);
	execve("/sbin/init",argv_init,envp_init);
	execve("/etc/init",argv_init,envp_init);
	execve("/bin/init",argv_init,envp_init);
	execve("/bin/sh",argv_init,envp_init);
	panic("No init found.  Try passing init= option to kernel.");
}
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