Home | History | Annotate | Line # | Download | only in kern
init_main.c revision 1.200
      1 /*	$NetBSD: init_main.c,v 1.200 2002/05/27 13:46:45 itojun Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1995 Christopher G. Demetriou.  All rights reserved.
      5  * Copyright (c) 1982, 1986, 1989, 1991, 1992, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  * (c) UNIX System Laboratories, Inc.
      8  * All or some portions of this file are derived from material licensed
      9  * to the University of California by American Telephone and Telegraph
     10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     11  * the permission of UNIX System Laboratories, Inc.
     12  *
     13  * Redistribution and use in source and binary forms, with or without
     14  * modification, are permitted provided that the following conditions
     15  * are met:
     16  * 1. Redistributions of source code must retain the above copyright
     17  *    notice, this list of conditions and the following disclaimer.
     18  * 2. Redistributions in binary form must reproduce the above copyright
     19  *    notice, this list of conditions and the following disclaimer in the
     20  *    documentation and/or other materials provided with the distribution.
     21  * 3. All advertising materials mentioning features or use of this software
     22  *    must display the following acknowledgement:
     23  *	This product includes software developed by the University of
     24  *	California, Berkeley and its contributors.
     25  * 4. Neither the name of the University nor the names of its contributors
     26  *    may be used to endorse or promote products derived from this software
     27  *    without specific prior written permission.
     28  *
     29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     39  * SUCH DAMAGE.
     40  *
     41  *	@(#)init_main.c	8.16 (Berkeley) 5/14/95
     42  */
     43 
     44 #include <sys/cdefs.h>
     45 __KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.200 2002/05/27 13:46:45 itojun Exp $");
     46 
     47 #include "fs_nfs.h"
     48 #include "opt_nfsserver.h"
     49 #include "opt_sysv.h"
     50 #include "opt_maxuprc.h"
     51 #include "opt_multiprocessor.h"
     52 #include "opt_pipe.h"
     53 #include "opt_syscall_debug.h"
     54 
     55 #include "rnd.h"
     56 
     57 #include <sys/param.h>
     58 #include <sys/acct.h>
     59 #include <sys/filedesc.h>
     60 #include <sys/file.h>
     61 #include <sys/errno.h>
     62 #include <sys/callout.h>
     63 #include <sys/kernel.h>
     64 #include <sys/mount.h>
     65 #include <sys/map.h>
     66 #include <sys/proc.h>
     67 #include <sys/kthread.h>
     68 #include <sys/resourcevar.h>
     69 #include <sys/signalvar.h>
     70 #include <sys/systm.h>
     71 #include <sys/vnode.h>
     72 #include <sys/tty.h>
     73 #include <sys/conf.h>
     74 #include <sys/disklabel.h>
     75 #include <sys/buf.h>
     76 #include <sys/device.h>
     77 #include <sys/disk.h>
     78 #include <sys/exec.h>
     79 #include <sys/socketvar.h>
     80 #include <sys/protosw.h>
     81 #include <sys/reboot.h>
     82 #include <sys/user.h>
     83 #include <sys/sysctl.h>
     84 #ifdef SYSVSHM
     85 #include <sys/shm.h>
     86 #endif
     87 #ifdef SYSVSEM
     88 #include <sys/sem.h>
     89 #endif
     90 #ifdef SYSVMSG
     91 #include <sys/msg.h>
     92 #endif
     93 #include <sys/domain.h>
     94 #include <sys/mbuf.h>
     95 #include <sys/namei.h>
     96 #if NRND > 0
     97 #include <sys/rnd.h>
     98 #endif
     99 #ifndef PIPE_SOCKETPAIR
    100 #include <sys/pipe.h>
    101 #endif
    102 
    103 #include <sys/syscall.h>
    104 #include <sys/syscallargs.h>
    105 
    106 #include <ufs/ufs/quota.h>
    107 
    108 #include <miscfs/genfs/genfs.h>
    109 #include <miscfs/syncfs/syncfs.h>
    110 
    111 #include <machine/cpu.h>
    112 
    113 #include <uvm/uvm.h>
    114 
    115 #include <net/if.h>
    116 #include <net/raw_cb.h>
    117 
    118 const char copyright[] =
    119 "Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002\n"
    120 "    The NetBSD Foundation, Inc.  All rights reserved.\n"
    121 "Copyright (c) 1982, 1986, 1989, 1991, 1993\n"
    122 "    The Regents of the University of California.  All rights reserved.\n"
    123 "\n";
    124 
    125 /* Components of the first process -- never freed. */
    126 struct	session session0;
    127 struct	pgrp pgrp0;
    128 struct	proc proc0;
    129 struct	pcred cred0;
    130 struct	filedesc0 filedesc0;
    131 struct	cwdinfo cwdi0;
    132 struct	plimit limit0;
    133 struct	vmspace vmspace0;
    134 struct	sigacts sigacts0;
    135 #ifndef curproc
    136 struct	proc *curproc = &proc0;
    137 #endif
    138 struct	proc *initproc;
    139 
    140 int	cmask = CMASK;
    141 extern	struct user *proc0paddr;
    142 
    143 struct	vnode *rootvp, *swapdev_vp;
    144 int	boothowto;
    145 int	cold = 1;			/* still working on startup */
    146 struct	timeval boottime;
    147 
    148 __volatile int start_init_exec;		/* semaphore for start_init() */
    149 
    150 static void check_console(struct proc *p);
    151 static void start_init(void *);
    152 void main(void);
    153 
    154 extern const struct emul emul_netbsd;	/* defined in kern_exec.c */
    155 
    156 /*
    157  * System startup; initialize the world, create process 0, mount root
    158  * filesystem, and fork to create init and pagedaemon.  Most of the
    159  * hard work is done in the lower-level initialization routines including
    160  * startup(), which does memory initialization and autoconfiguration.
    161  */
    162 void
    163 main(void)
    164 {
    165 	struct proc *p;
    166 	struct pdevinit *pdev;
    167 	int i, s, error;
    168 	rlim_t lim;
    169 	extern struct pdevinit pdevinit[];
    170 	extern void schedcpu(void *);
    171 #if defined(NFSSERVER) || defined(NFS)
    172 	extern void nfs_init(void);
    173 #endif
    174 #ifdef NVNODE_IMPLICIT
    175 	int usevnodes;
    176 #endif
    177 
    178 	/*
    179 	 * Initialize the current process pointer (curproc) before
    180 	 * any possible traps/probes to simplify trap processing.
    181 	 */
    182 	p = &proc0;
    183 	curproc = p;
    184 	p->p_cpu = curcpu();
    185 	/*
    186 	 * Attempt to find console and initialize
    187 	 * in case of early panic or other messages.
    188 	 */
    189 	consinit();
    190 	printf("%s", copyright);
    191 
    192 	KERNEL_LOCK_INIT();
    193 
    194 	uvm_init();
    195 
    196 	/* Do machine-dependent initialization. */
    197 	cpu_startup();
    198 
    199 	/* Initialize callouts. */
    200 	callout_startup();
    201 
    202 	/*
    203 	 * Initialize mbuf's.  Do this now because we might attempt to
    204 	 * allocate mbufs or mbuf clusters during autoconfiguration.
    205 	 */
    206 	mbinit();
    207 
    208 	/* Initialize sockets. */
    209 	soinit();
    210 
    211 	/*
    212 	 * The following 3 things must be done before autoconfiguration.
    213 	 */
    214 	disk_init();		/* initialize disk list */
    215 	tty_init();		/* initialize tty list */
    216 #if NRND > 0
    217 	rnd_init();		/* initialize RNG */
    218 #endif
    219 
    220 	/* Initialize the sysctl subsystem. */
    221 	sysctl_init();
    222 
    223 	/*
    224 	 * Initialize process and pgrp structures.
    225 	 */
    226 	procinit();
    227 
    228 	/*
    229 	 * Create process 0 (the swapper).
    230 	 */
    231 	s = proclist_lock_write();
    232 	LIST_INSERT_HEAD(&allproc, p, p_list);
    233 	LIST_INSERT_HEAD(PIDHASH(p->p_pid), p, p_hash);
    234 	proclist_unlock_write(s);
    235 
    236 	p->p_pgrp = &pgrp0;
    237 	LIST_INSERT_HEAD(PGRPHASH(0), &pgrp0, pg_hash);
    238 	LIST_INIT(&pgrp0.pg_members);
    239 	LIST_INSERT_HEAD(&pgrp0.pg_members, p, p_pglist);
    240 
    241 	pgrp0.pg_session = &session0;
    242 	session0.s_count = 1;
    243 	session0.s_sid = p->p_pid;
    244 	session0.s_leader = p;
    245 
    246 	/*
    247 	 * Set P_NOCLDWAIT so that kernel threads are reparented to
    248 	 * init(8) when they exit.  init(8) can easily wait them out
    249 	 * for us.
    250 	 */
    251 	p->p_flag = P_INMEM | P_SYSTEM | P_NOCLDWAIT;
    252 	p->p_stat = SONPROC;
    253 	p->p_nice = NZERO;
    254 	p->p_emul = &emul_netbsd;
    255 #ifdef __HAVE_SYSCALL_INTERN
    256 	(*p->p_emul->e_syscall_intern)(p);
    257 #endif
    258 	strncpy(p->p_comm, "swapper", MAXCOMLEN);
    259 
    260 	callout_init(&p->p_realit_ch);
    261 	callout_init(&p->p_tsleep_ch);
    262 
    263 	/* Create credentials. */
    264 	cred0.p_refcnt = 1;
    265 	p->p_cred = &cred0;
    266 	p->p_ucred = crget();
    267 	p->p_ucred->cr_ngroups = 1;	/* group 0 */
    268 
    269 	/* Create the file descriptor table. */
    270 	finit();
    271 	p->p_fd = &filedesc0.fd_fd;
    272 	fdinit1(&filedesc0);
    273 
    274 	/* Create the CWD info. */
    275 	p->p_cwdi = &cwdi0;
    276 	cwdi0.cwdi_cmask = cmask;
    277 	cwdi0.cwdi_refcnt = 1;
    278 
    279 	/* Create the limits structures. */
    280 	p->p_limit = &limit0;
    281 	for (i = 0; i < sizeof(p->p_rlimit)/sizeof(p->p_rlimit[0]); i++)
    282 		limit0.pl_rlimit[i].rlim_cur =
    283 		    limit0.pl_rlimit[i].rlim_max = RLIM_INFINITY;
    284 
    285 	limit0.pl_rlimit[RLIMIT_NOFILE].rlim_max = maxfiles;
    286 	limit0.pl_rlimit[RLIMIT_NOFILE].rlim_cur =
    287 	    maxfiles < NOFILE ? maxfiles : NOFILE;
    288 
    289 	limit0.pl_rlimit[RLIMIT_NPROC].rlim_max = maxproc;
    290 	limit0.pl_rlimit[RLIMIT_NPROC].rlim_cur =
    291 	    maxproc < MAXUPRC ? maxproc : MAXUPRC;
    292 
    293 	lim = ptoa(uvmexp.free);
    294 	limit0.pl_rlimit[RLIMIT_RSS].rlim_max = lim;
    295 	limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_max = lim;
    296 	limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = lim / 3;
    297 	limit0.pl_corename = defcorename;
    298 	limit0.p_refcnt = 1;
    299 
    300 	/*
    301 	 * Initialize proc0's vmspace, which uses the kernel pmap.
    302 	 * All kernel processes (which never have user space mappings)
    303 	 * share proc0's vmspace, and thus, the kernel pmap.
    304 	 */
    305 	uvmspace_init(&vmspace0, pmap_kernel(), round_page(VM_MIN_ADDRESS),
    306 	    trunc_page(VM_MAX_ADDRESS));
    307 	p->p_vmspace = &vmspace0;
    308 
    309 	p->p_addr = proc0paddr;				/* XXX */
    310 
    311 	/*
    312 	 * We continue to place resource usage info in the
    313 	 * user struct so they're pageable.
    314 	 */
    315 	p->p_stats = &p->p_addr->u_stats;
    316 
    317 	/*
    318 	 * Charge root for one process.
    319 	 */
    320 	(void)chgproccnt(0, 1);
    321 
    322 	rqinit();
    323 
    324 	/* Configure virtual memory system, set vm rlimits. */
    325 	uvm_init_limits(p);
    326 
    327 	/* Initialize the file systems. */
    328 #if defined(NFSSERVER) || defined(NFS)
    329 	nfs_init();			/* initialize server/shared data */
    330 #endif
    331 #ifdef NVNODE_IMPLICIT
    332 	/*
    333 	 * If maximum number of vnodes in namei vnode cache is not explicitly
    334 	 * defined in kernel config, adjust the number such as we use roughly
    335 	 * 0.5% of memory for vnode cache (but not less than NVNODE vnodes).
    336 	 */
    337 	usevnodes = (ptoa((unsigned)physmem) / 200) / sizeof(struct vnode);
    338 	if (usevnodes > desiredvnodes)
    339 		desiredvnodes = usevnodes;
    340 #endif
    341 	vfsinit();
    342 
    343 	/* Configure the system hardware.  This will enable interrupts. */
    344 	configure();
    345 
    346 	ubc_init();		/* must be after autoconfig */
    347 
    348 	/* Lock the kernel on behalf of proc0. */
    349 	KERNEL_PROC_LOCK(p);
    350 
    351 #ifdef SYSVSHM
    352 	/* Initialize System V style shared memory. */
    353 	shminit();
    354 #endif
    355 
    356 #ifdef SYSVSEM
    357 	/* Initialize System V style semaphores. */
    358 	seminit();
    359 #endif
    360 
    361 #ifdef SYSVMSG
    362 	/* Initialize System V style message queues. */
    363 	msginit();
    364 #endif
    365 
    366 	/* Attach pseudo-devices. */
    367 	for (pdev = pdevinit; pdev->pdev_attach != NULL; pdev++)
    368 		(*pdev->pdev_attach)(pdev->pdev_count);
    369 
    370 	/*
    371 	 * Initialize protocols.  Block reception of incoming packets
    372 	 * until everything is ready.
    373 	 */
    374 	s = splnet();
    375 	ifinit();
    376 	domaininit();
    377 	if_attachdomain();
    378 	splx(s);
    379 
    380 #ifdef GPROF
    381 	/* Initialize kernel profiling. */
    382 	kmstartup();
    383 #endif
    384 
    385 	/* Initialize system accouting. */
    386 	acct_init();
    387 
    388 	/*
    389 	 * Initialize signal-related data structures, and signal state
    390 	 * for proc0.
    391 	 */
    392 	signal_init();
    393 	p->p_sigacts = &sigacts0;
    394 	siginit(p);
    395 
    396 	/* Kick off timeout driven events by calling first time. */
    397 	schedcpu(NULL);
    398 
    399 	/*
    400 	 * Create process 1 (init(8)).  We do this now, as Unix has
    401 	 * historically had init be process 1, and changing this would
    402 	 * probably upset a lot of people.
    403 	 *
    404 	 * Note that process 1 won't immediately exec init(8), but will
    405 	 * wait for us to inform it that the root file system has been
    406 	 * mounted.
    407 	 */
    408 	if (fork1(p, 0, SIGCHLD, NULL, 0, start_init, NULL, NULL, &initproc))
    409 		panic("fork init");
    410 
    411 	/*
    412 	 * Create any kernel threads who's creation was deferred because
    413 	 * initproc had not yet been created.
    414 	 */
    415 	kthread_run_deferred_queue();
    416 
    417 	/*
    418 	 * Now that device driver threads have been created, wait for
    419 	 * them to finish any deferred autoconfiguration.  Note we don't
    420 	 * need to lock this semaphore, since we haven't booted any
    421 	 * secondary processors, yet.
    422 	 */
    423 	while (config_pending)
    424 		(void) tsleep((void *)&config_pending, PWAIT, "cfpend", 0);
    425 
    426 	/*
    427 	 * Now that autoconfiguration has completed, we can determine
    428 	 * the root and dump devices.
    429 	 */
    430 	cpu_rootconf();
    431 	cpu_dumpconf();
    432 
    433 	/* Mount the root file system. */
    434 	do {
    435 		domountroothook();
    436 		if ((error = vfs_mountroot())) {
    437 			printf("cannot mount root, error = %d\n", error);
    438 			boothowto |= RB_ASKNAME;
    439 			setroot(root_device,
    440 			    (rootdev != NODEV) ? DISKPART(rootdev) : 0);
    441 		}
    442 	} while (error != 0);
    443 	mountroothook_destroy();
    444 
    445 	mountlist.cqh_first->mnt_flag |= MNT_ROOTFS;
    446 	mountlist.cqh_first->mnt_op->vfs_refcount++;
    447 
    448 	/*
    449 	 * Get the vnode for '/'.  Set filedesc0.fd_fd.fd_cdir to
    450 	 * reference it.
    451 	 */
    452 	if (VFS_ROOT(mountlist.cqh_first, &rootvnode))
    453 		panic("cannot find root vnode");
    454 	cwdi0.cwdi_cdir = rootvnode;
    455 	VREF(cwdi0.cwdi_cdir);
    456 	VOP_UNLOCK(rootvnode, 0);
    457 	cwdi0.cwdi_rdir = NULL;
    458 
    459 	/*
    460 	 * Now that root is mounted, we can fixup initproc's CWD
    461 	 * info.  All other processes are kthreads, which merely
    462 	 * share proc0's CWD info.
    463 	 */
    464 	initproc->p_cwdi->cwdi_cdir = rootvnode;
    465 	VREF(initproc->p_cwdi->cwdi_cdir);
    466 	initproc->p_cwdi->cwdi_rdir = NULL;
    467 
    468 	/*
    469 	 * Now can look at time, having had a chance to verify the time
    470 	 * from the file system.  Reset p->p_rtime as it may have been
    471 	 * munched in mi_switch() after the time got set.
    472 	 */
    473 	proclist_lock_read();
    474 	s = splsched();
    475 	for (p = LIST_FIRST(&allproc); p != NULL;
    476 	     p = LIST_NEXT(p, p_list)) {
    477 		p->p_stats->p_start = mono_time = boottime = time;
    478 		if (p->p_cpu != NULL)
    479 			p->p_cpu->ci_schedstate.spc_runtime = time;
    480 		p->p_rtime.tv_sec = p->p_rtime.tv_usec = 0;
    481 	}
    482 	splx(s);
    483 	proclist_unlock_read();
    484 
    485 	/* Create the pageout daemon kernel thread. */
    486 	uvm_swap_init();
    487 	if (kthread_create1(uvm_pageout, NULL, NULL, "pagedaemon"))
    488 		panic("fork pagedaemon");
    489 
    490 	/* Create the process reaper kernel thread. */
    491 	if (kthread_create1(reaper, NULL, NULL, "reaper"))
    492 		panic("fork reaper");
    493 
    494 	/* Create the filesystem syncer kernel thread. */
    495 	if (kthread_create1(sched_sync, NULL, NULL, "ioflush"))
    496 		panic("fork syncer");
    497 
    498 	/* Create the aiodone daemon kernel thread. */
    499 	if (kthread_create1(uvm_aiodone_daemon, NULL, NULL, "aiodoned"))
    500 		panic("fork aiodoned");
    501 
    502 #if defined(MULTIPROCESSOR)
    503 	/* Boot the secondary processors. */
    504 	cpu_boot_secondary_processors();
    505 #endif
    506 
    507 	/* Initialize exec structures */
    508 	exec_init(1);
    509 
    510 #ifndef PIPE_SOCKETPAIR
    511 	/* Initialize pipe structures */
    512 	pipe_init();
    513 #endif
    514 
    515 	/*
    516 	 * Okay, now we can let init(8) exec!  It's off to userland!
    517 	 */
    518 	start_init_exec = 1;
    519 	wakeup((void *)&start_init_exec);
    520 
    521 	/* The scheduler is an infinite loop. */
    522 	uvm_scheduler();
    523 	/* NOTREACHED */
    524 }
    525 
    526 static void
    527 check_console(struct proc *p)
    528 {
    529 	struct nameidata nd;
    530 	int error;
    531 
    532 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, "/dev/console", p);
    533 	error = namei(&nd);
    534 	if (error == 0)
    535 		vrele(nd.ni_vp);
    536 	else if (error == ENOENT)
    537 		printf("warning: no /dev/console\n");
    538 	else
    539 		printf("warning: lookup /dev/console: error %d\n", error);
    540 }
    541 
    542 /*
    543  * List of paths to try when searching for "init".
    544  */
    545 static const char *initpaths[] = {
    546 	"/sbin/init",
    547 	"/sbin/oinit",
    548 	"/sbin/init.bak",
    549 	NULL,
    550 };
    551 
    552 /*
    553  * Start the initial user process; try exec'ing each pathname in "initpaths".
    554  * The program is invoked with one argument containing the boot flags.
    555  */
    556 static void
    557 start_init(void *arg)
    558 {
    559 	struct proc *p = arg;
    560 	vaddr_t addr;
    561 	struct sys_execve_args /* {
    562 		syscallarg(const char *) path;
    563 		syscallarg(char * const *) argp;
    564 		syscallarg(char * const *) envp;
    565 	} */ args;
    566 	int options, i, error;
    567 	register_t retval[2];
    568 	char flags[4], *flagsp;
    569 	const char **pathp, *path, *slash;
    570 	char *ucp, **uap, *arg0, *arg1 = NULL;
    571 
    572 	/*
    573 	 * Now in process 1.
    574 	 */
    575 	strncpy(p->p_comm, "init", MAXCOMLEN);
    576 
    577 	/*
    578 	 * Wait for main() to tell us that it's safe to exec.
    579 	 */
    580 	while (start_init_exec == 0)
    581 		(void) tsleep((void *)&start_init_exec, PWAIT, "initexec", 0);
    582 
    583 	/*
    584 	 * This is not the right way to do this.  We really should
    585 	 * hand-craft a descriptor onto /dev/console to hand to init,
    586 	 * but that's a _lot_ more work, and the benefit from this easy
    587 	 * hack makes up for the "good is the enemy of the best" effect.
    588 	 */
    589 	check_console(p);
    590 
    591 	/*
    592 	 * Need just enough stack to hold the faked-up "execve()" arguments.
    593 	 */
    594 	addr = USRSTACK - PAGE_SIZE;
    595 	if (uvm_map(&p->p_vmspace->vm_map, &addr, PAGE_SIZE,
    596                     NULL, UVM_UNKNOWN_OFFSET, 0,
    597                     UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_COPY,
    598 		    UVM_ADV_NORMAL,
    599                     UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW)) != 0)
    600 		panic("init: couldn't allocate argument space");
    601 	p->p_vmspace->vm_maxsaddr = (caddr_t)addr;
    602 
    603 	for (pathp = &initpaths[0]; (path = *pathp) != NULL; pathp++) {
    604 		ucp = (char *)(addr + PAGE_SIZE);
    605 
    606 		/*
    607 		 * Construct the boot flag argument.
    608 		 */
    609 		flagsp = flags;
    610 		*flagsp++ = '-';
    611 		options = 0;
    612 
    613 		if (boothowto & RB_SINGLE) {
    614 			*flagsp++ = 's';
    615 			options = 1;
    616 		}
    617 #ifdef notyet
    618 		if (boothowto & RB_FASTBOOT) {
    619 			*flagsp++ = 'f';
    620 			options = 1;
    621 		}
    622 #endif
    623 
    624 		/*
    625 		 * Move out the flags (arg 1), if necessary.
    626 		 */
    627 		if (options != 0) {
    628 			*flagsp++ = '\0';
    629 			i = flagsp - flags;
    630 #ifdef DEBUG
    631 			printf("init: copying out flags `%s' %d\n", flags, i);
    632 #endif
    633 			(void)copyout((caddr_t)flags, (caddr_t)(ucp -= i), i);
    634 			arg1 = ucp;
    635 		}
    636 
    637 		/*
    638 		 * Move out the file name (also arg 0).
    639 		 */
    640 		i = strlen(path) + 1;
    641 #ifdef DEBUG
    642 		printf("init: copying out path `%s' %d\n", path, i);
    643 #endif
    644 		(void)copyout((caddr_t)path, (caddr_t)(ucp -= i), i);
    645 		arg0 = ucp;
    646 
    647 		/*
    648 		 * Move out the arg pointers.
    649 		 */
    650 		uap = (char **)((long)ucp & ~ALIGNBYTES);
    651 		(void)suword((caddr_t)--uap, 0);	/* terminator */
    652 		if (options != 0)
    653 			(void)suword((caddr_t)--uap, (long)arg1);
    654 		slash = strrchr(path, '/');
    655 		if (slash)
    656 			(void)suword((caddr_t)--uap,
    657 			    (long)arg0 + (slash + 1 - path));
    658 		else
    659 			(void)suword((caddr_t)--uap, (long)arg0);
    660 
    661 		/*
    662 		 * Point at the arguments.
    663 		 */
    664 		SCARG(&args, path) = arg0;
    665 		SCARG(&args, argp) = uap;
    666 		SCARG(&args, envp) = NULL;
    667 
    668 		/*
    669 		 * Now try to exec the program.  If can't for any reason
    670 		 * other than it doesn't exist, complain.
    671 		 */
    672 		error = sys_execve(p, &args, retval);
    673 		if (error == 0 || error == EJUSTRETURN) {
    674 			KERNEL_PROC_UNLOCK(p);
    675 			return;
    676 		}
    677 		if (error != ENOENT)
    678 			printf("exec %s: error %d\n", path, error);
    679 	}
    680 	printf("init: not found\n");
    681 	panic("no init");
    682 }
    683