xref: /freebsd/sys/kern/init_main.c (revision 6e8394b8baa7d5d9153ab90de6824bcd19b3b4e1)
1 /*
2  * Copyright (c) 1995 Terrence R. Lambert
3  * All rights reserved.
4  *
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	8.9 (Berkeley) 1/21/94
42  * $Id: init_main.c,v 1.121 1999/05/09 20:42:45 peter Exp $
43  */
44 
45 #include "opt_devfs.h"
46 #include "opt_init_path.h"
47 
48 #include <sys/param.h>
49 #include <sys/file.h>
50 #include <sys/filedesc.h>
51 #include <sys/kernel.h>
52 #include <sys/mount.h>
53 #include <sys/sysctl.h>
54 #include <sys/proc.h>
55 #include <sys/resourcevar.h>
56 #include <sys/signalvar.h>
57 #include <sys/systm.h>
58 #include <sys/vnode.h>
59 #include <sys/sysent.h>
60 #include <sys/reboot.h>
61 #include <sys/sysproto.h>
62 #include <sys/vmmeter.h>
63 #include <sys/unistd.h>
64 #include <sys/malloc.h>
65 
66 #include <machine/cpu.h>
67 
68 #include <vm/vm.h>
69 #include <vm/vm_param.h>
70 #include <vm/vm_prot.h>
71 #include <sys/lock.h>
72 #include <vm/pmap.h>
73 #include <vm/vm_map.h>
74 #include <sys/user.h>
75 #include <sys/copyright.h>
76 
77 extern struct linker_set	sysinit_set;	/* XXX */
78 
79 extern void mi_startup __P((void *framep));
80 
81 /* Components of the first process -- never freed. */
82 static struct session session0;
83 static struct pgrp pgrp0;
84 struct	proc proc0;
85 static struct pcred cred0;
86 static struct procsig procsig0;
87 static struct filedesc0 filedesc0;
88 static struct plimit limit0;
89 static struct vmspace vmspace0;
90 struct	proc *initproc;
91 
92 int cmask = CMASK;
93 extern	struct user *proc0paddr;
94 
95 struct	vnode *rootvp;
96 int	boothowto = 0;		/* initialized so that it can be patched */
97 
98 struct	timeval boottime;
99 SYSCTL_STRUCT(_kern, KERN_BOOTTIME, boottime, CTLFLAG_RD,
100     &boottime, timeval, "System boottime");
101 
102 /*
103  * Promiscuous argument pass for start_init()
104  *
105  * This is a kludge because we use a return from mi_startup() rather than a call
106  * to a new routine in locore.s to kick the kernel alive from locore.s.
107  */
108 static void	*init_framep;
109 
110 /*
111  * This ensures that there is at least one entry so that the sysinit_set
112  * symbol is not undefined.  A sybsystem ID of SI_SUB_DUMMY is never
113  * executed.
114  */
115 SYSINIT(placeholder, SI_SUB_DUMMY,SI_ORDER_ANY, NULL, NULL)
116 
117 /*
118  * The sysinit table itself.  Items are checked off as the are run.
119  * If we want to register new sysinit types, add them to newsysinit.
120  */
121 struct sysinit **sysinit = (struct sysinit **)sysinit_set.ls_items;
122 struct sysinit **newsysinit;
123 
124 /*
125  * Merge a new sysinit set into the current set, reallocating it if
126  * necessary.  This can only be called after malloc is running.
127  */
128 void
129 sysinit_add(set)
130 	struct sysinit **set;
131 {
132 	struct sysinit **newset;
133 	struct sysinit **sipp;
134 	struct sysinit **xipp;
135 	int count = 0;
136 
137 	if (newsysinit)
138 		for (sipp = newsysinit; *sipp; sipp++)
139 			count++;
140 	else
141 		for (sipp = sysinit; *sipp; sipp++)
142 			count++;
143 	for (sipp = set; *sipp; sipp++)
144 		count++;
145 	count++;		/* Trailing NULL */
146 	newset = malloc(count * sizeof(*sipp), M_TEMP, M_NOWAIT);
147 	if (newset == NULL)
148 		panic("cannot malloc for sysinit");
149 	xipp = newset;
150 	if (newsysinit)
151 		for (sipp = newsysinit; *sipp; sipp++)
152 			*xipp++ = *sipp;
153 	else
154 		for (sipp = sysinit; *sipp; sipp++)
155 			*xipp++ = *sipp;
156 	for (sipp = set; *sipp; sipp++)
157 		*xipp++ = *sipp;
158 	*xipp = NULL;
159 	if (newsysinit)
160 		free(newsysinit, M_TEMP);
161 	newsysinit = newset;
162 }
163 
164 /*
165  * System startup; initialize the world, create process 0, mount root
166  * filesystem, and fork to create init and pagedaemon.  Most of the
167  * hard work is done in the lower-level initialization routines including
168  * startup(), which does memory initialization and autoconfiguration.
169  *
170  * This allows simple addition of new kernel subsystems that require
171  * boot time initialization.  It also allows substitution of subsystem
172  * (for instance, a scheduler, kernel profiler, or VM system) by object
173  * module.  Finally, it allows for optional "kernel threads".
174  */
175 void
176 mi_startup(framep)
177 	void *framep;
178 {
179 
180 	register struct sysinit **sipp;		/* system initialization*/
181 	register struct sysinit **xipp;		/* interior loop of sort*/
182 	register struct sysinit *save;		/* bubble*/
183 
184 	/*
185 	 * Copy the locore.s frame pointer for proc0, this is forked into
186 	 * all other processes.
187 	 */
188 	init_framep = framep;
189 
190 restart:
191 	/*
192 	 * Perform a bubble sort of the system initialization objects by
193 	 * their subsystem (primary key) and order (secondary key).
194 	 */
195 	for (sipp = sysinit; *sipp; sipp++) {
196 		for (xipp = sipp + 1; *xipp; xipp++) {
197 			if ((*sipp)->subsystem < (*xipp)->subsystem ||
198 			     ((*sipp)->subsystem == (*xipp)->subsystem &&
199 			      (*sipp)->order < (*xipp)->order))
200 				continue;	/* skip*/
201 			save = *sipp;
202 			*sipp = *xipp;
203 			*xipp = save;
204 		}
205 	}
206 
207 	/*
208 	 * Traverse the (now) ordered list of system initialization tasks.
209 	 * Perform each task, and continue on to the next task.
210 	 *
211 	 * The last item on the list is expected to be the scheduler,
212 	 * which will not return.
213 	 */
214 	for (sipp = sysinit; *sipp; sipp++) {
215 
216 		if ((*sipp)->subsystem == SI_SUB_DUMMY)
217 			continue;	/* skip dummy task(s)*/
218 
219 		if ((*sipp)->subsystem == SI_SUB_DONE)
220 			continue;
221 
222 		switch( (*sipp)->type) {
223 		case SI_TYPE_DEFAULT:
224 			/* no special processing*/
225 			(*((*sipp)->func))((*sipp)->udata);
226 			break;
227 
228 		case SI_TYPE_KTHREAD:
229 			/* kernel thread*/
230 			if (fork1(&proc0, RFMEM|RFFDG|RFPROC))
231 				panic("fork kernel thread");
232 			cpu_set_fork_handler(pfind(proc0.p_retval[0]),
233 			    (*sipp)->func, (*sipp)->udata);
234 			break;
235 
236 		case SI_TYPE_KPROCESS:
237 			if (fork1(&proc0, RFFDG|RFPROC))
238 				panic("fork kernel process");
239 			cpu_set_fork_handler(pfind(proc0.p_retval[0]),
240 			    (*sipp)->func, (*sipp)->udata);
241 			break;
242 
243 		default:
244 			panic("init_main: unrecognized init type");
245 		}
246 
247 		/* Check off the one we're just done */
248 		(*sipp)->subsystem = SI_SUB_DONE;
249 
250 		/* Check if we've installed more sysinit items via KLD */
251 		if (newsysinit != NULL) {
252 			if (sysinit != (struct sysinit **)sysinit_set.ls_items)
253 				free(sysinit, M_TEMP);
254 			sysinit = newsysinit;
255 			newsysinit = NULL;
256 			goto restart;
257 		}
258 	}
259 
260 	panic("Shouldn't get here!");
261 	/* NOTREACHED*/
262 }
263 
264 
265 /*
266  * Start a kernel process.  This is called after a fork() call in
267  * mi_startup() in the file kern/init_main.c.
268  *
269  * This function is used to start "internal" daemons.
270  */
271 /* ARGSUSED*/
272 void
273 kproc_start(udata)
274 	const void *udata;
275 {
276 	const struct kproc_desc	*kp = udata;
277 	struct proc		*p = curproc;
278 
279 #ifdef DIAGNOSTIC
280 	printf("Start pid=%d <%s>\n",p->p_pid, kp->arg0);
281 #endif
282 
283 	/* save a global descriptor, if desired*/
284 	if( kp->global_procpp != NULL)
285 		*kp->global_procpp	= p;
286 
287 	/* this is a non-swapped system process*/
288 	p->p_flag |= P_INMEM | P_SYSTEM;
289 
290 	/* set up arg0 for 'ps', et al*/
291 	strcpy( p->p_comm, kp->arg0);
292 
293 	/* call the processes' main()...*/
294 	(*kp->func)();
295 
296 	/* NOTREACHED */
297 	panic("kproc_start: %s", kp->arg0);
298 }
299 
300 
301 /*
302  ***************************************************************************
303  ****
304  **** The following SYSINIT's belong elsewhere, but have not yet
305  **** been moved.
306  ****
307  ***************************************************************************
308  */
309 #ifdef OMIT
310 /*
311  * Handled by vfs_mountroot (bad idea) at this time... should be
312  * done the same as 4.4Lite2.
313  */
314 SYSINIT(swapinit, SI_SUB_SWAP, SI_ORDER_FIRST, swapinit, NULL)
315 #endif	/* OMIT*/
316 
317 static void print_caddr_t __P((void *data));
318 static void
319 print_caddr_t(data)
320 	void *data;
321 {
322 	printf("%s", (char *)data);
323 }
324 SYSINIT(announce, SI_SUB_COPYRIGHT, SI_ORDER_FIRST, print_caddr_t, copyright)
325 
326 
327 /*
328  ***************************************************************************
329  ****
330  **** The two following SYSINT's are proc0 specific glue code.  I am not
331  **** convinced that they can not be safely combined, but their order of
332  **** operation has been maintained as the same as the original init_main.c
333  **** for right now.
334  ****
335  **** These probably belong in init_proc.c or kern_proc.c, since they
336  **** deal with proc0 (the fork template process).
337  ****
338  ***************************************************************************
339  */
340 /* ARGSUSED*/
341 static void proc0_init __P((void *dummy));
342 static void
343 proc0_init(dummy)
344 	void *dummy;
345 {
346 	register struct proc		*p;
347 	register struct filedesc0	*fdp;
348 	register unsigned i;
349 
350 	p = &proc0;
351 
352 	/*
353 	 * Initialize process and pgrp structures.
354 	 */
355 	procinit();
356 
357 	/*
358 	 * Initialize sleep queue hash table
359 	 */
360 	sleepinit();
361 
362 	/*
363 	 * additional VM structures
364 	 */
365 	vm_init2();
366 
367 	/*
368 	 * Create process 0 (the swapper).
369 	 */
370 	LIST_INSERT_HEAD(&allproc, p, p_list);
371 	p->p_pgrp = &pgrp0;
372 	LIST_INSERT_HEAD(PGRPHASH(0), &pgrp0, pg_hash);
373 	LIST_INIT(&pgrp0.pg_members);
374 	LIST_INSERT_HEAD(&pgrp0.pg_members, p, p_pglist);
375 
376 	pgrp0.pg_session = &session0;
377 	session0.s_count = 1;
378 	session0.s_leader = p;
379 
380 	p->p_sysent = &aout_sysvec;
381 
382 	p->p_flag = P_INMEM | P_SYSTEM;
383 	p->p_stat = SRUN;
384 	p->p_nice = NZERO;
385 	p->p_rtprio.type = RTP_PRIO_NORMAL;
386 	p->p_rtprio.prio = 0;
387 
388 /*
389  * Link for kernel based threads
390  */
391 	p->p_peers = 0;
392 	p->p_leader = p;
393 
394 	bcopy("swapper", p->p_comm, sizeof ("swapper"));
395 
396 	/* Create credentials. */
397 	cred0.p_refcnt = 1;
398 	p->p_cred = &cred0;
399 	p->p_ucred = crget();
400 	p->p_ucred->cr_ngroups = 1;	/* group 0 */
401 
402 	/* Don't jail it */
403 	p->p_prison = 0;
404 
405 	/* Create procsig. */
406 	p->p_procsig = &procsig0;
407 	p->p_procsig->ps_refcnt = 1;
408 
409 	/* Create the file descriptor table. */
410 	fdp = &filedesc0;
411 	p->p_fd = &fdp->fd_fd;
412 	fdp->fd_fd.fd_refcnt = 1;
413 	fdp->fd_fd.fd_cmask = cmask;
414 	fdp->fd_fd.fd_ofiles = fdp->fd_dfiles;
415 	fdp->fd_fd.fd_ofileflags = fdp->fd_dfileflags;
416 	fdp->fd_fd.fd_nfiles = NDFILE;
417 
418 	/* Create the limits structures. */
419 	p->p_limit = &limit0;
420 	for (i = 0; i < sizeof(p->p_rlimit)/sizeof(p->p_rlimit[0]); i++)
421 		limit0.pl_rlimit[i].rlim_cur =
422 		    limit0.pl_rlimit[i].rlim_max = RLIM_INFINITY;
423 	limit0.pl_rlimit[RLIMIT_NOFILE].rlim_cur =
424 	    limit0.pl_rlimit[RLIMIT_NOFILE].rlim_max = maxfiles;
425 	limit0.pl_rlimit[RLIMIT_NPROC].rlim_cur =
426 	    limit0.pl_rlimit[RLIMIT_NPROC].rlim_max = maxproc;
427 	i = ptoa(cnt.v_free_count);
428 	limit0.pl_rlimit[RLIMIT_RSS].rlim_max = i;
429 	limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_max = i;
430 	limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = i / 3;
431 	limit0.p_cpulimit = RLIM_INFINITY;
432 	limit0.p_refcnt = 1;
433 
434 
435 	/* Allocate a prototype map so we have something to fork. */
436 	pmap_pinit0(vmspace_pmap(&vmspace0));
437 	p->p_vmspace = &vmspace0;
438 	vmspace0.vm_refcnt = 1;
439 	vm_map_init(&vmspace0.vm_map, round_page(VM_MIN_ADDRESS),
440 	    trunc_page(VM_MAXUSER_ADDRESS));
441 	vmspace0.vm_map.pmap = vmspace_pmap(&vmspace0);
442 	p->p_addr = proc0paddr;				/* XXX */
443 
444 #ifdef cpu_set_init_frame
445 	/*
446 	 * proc0 needs to have a coherent frame base in its stack.
447 	 */
448 	cpu_set_init_frame(p, init_framep);			/* XXX! */
449 #endif
450 
451 	/*
452 	 * We continue to place resource usage info and signal
453 	 * actions in the user struct so they're pageable.
454 	 */
455 	p->p_stats = &p->p_addr->u_stats;
456 	p->p_sigacts = &p->p_addr->u_sigacts;
457 
458 	/*
459 	 * Charge root for one process.
460 	 */
461 	(void)chgproccnt(0, 1);
462 
463 	/*
464 	 * Initialize the current process pointer (curproc) before
465 	 * any possible traps/probes to simplify trap processing.
466 	 */
467 	SET_CURPROC(p);
468 
469 }
470 SYSINIT(p0init, SI_SUB_INTRINSIC, SI_ORDER_FIRST, proc0_init, NULL)
471 
472 /* ARGSUSED*/
473 static void proc0_post __P((void *dummy));
474 static void
475 proc0_post(dummy)
476 	void *dummy;
477 {
478 	struct timespec ts;
479 
480 	/*
481 	 * Now we can look at the time, having had a chance to verify the
482 	 * time from the file system.  Pretend that proc0 started now.
483 	 */
484 	microtime(&proc0.p_stats->p_start);
485 	proc0.p_runtime = 0;
486 	microuptime(&switchtime);
487 	switchticks = ticks;
488 
489 	/*
490 	 * Give the ``random'' number generator a thump.
491 	 * XXX: Does read_random() contain enough bits to be used here ?
492 	 */
493 	nanotime(&ts);
494 	srandom(ts.tv_sec ^ ts.tv_nsec);
495 
496 	/* Initialize signal state for process 0. */
497 	siginit(&proc0);
498 }
499 SYSINIT(p0post, SI_SUB_INTRINSIC_POST, SI_ORDER_FIRST, proc0_post, NULL)
500 
501 
502 
503 
504 /*
505  ***************************************************************************
506  ****
507  **** The following SYSINIT's and glue code should be moved to the
508  **** respective files on a per subsystem basis.
509  ****
510  ***************************************************************************
511  */
512 
513 /* ARGSUSED */
514 static void root_conf __P((void *dummy));
515 static void
516 root_conf(dummy)
517 	void *dummy;
518 {
519 	cpu_rootconf();
520 }
521 SYSINIT(root_conf, SI_SUB_ROOT_CONF, SI_ORDER_FIRST, root_conf, NULL)
522 
523 /* ARGSUSED*/
524 static void xxx_vfs_root_fdtab __P((void *dummy));
525 static void
526 xxx_vfs_root_fdtab(dummy)
527 	void *dummy;
528 {
529 	register struct filedesc0	*fdp = &filedesc0;
530 
531 	/* Get the vnode for '/'.  Set fdp->fd_fd.fd_cdir to reference it. */
532 	if (VFS_ROOT(mountlist.cqh_first, &rootvnode))
533 		panic("cannot find root vnode");
534 	fdp->fd_fd.fd_cdir = rootvnode;
535 	VREF(fdp->fd_fd.fd_cdir);
536 	VOP_UNLOCK(rootvnode, 0, &proc0);
537 	fdp->fd_fd.fd_rdir = rootvnode;
538 }
539 SYSINIT(retrofit, SI_SUB_ROOT_FDTAB, SI_ORDER_FIRST, xxx_vfs_root_fdtab, NULL)
540 
541 
542 /*
543  ***************************************************************************
544  ****
545  **** The following code probably belongs in another file, like
546  **** kern/init_init.c.  It is here for two reasons only:
547  ****
548  ****	1)	This code returns to startup the system; this is
549  ****		abnormal for a kernel thread.
550  ****	2)	This code promiscuously uses init_frame
551  ****
552  ***************************************************************************
553  */
554 
555 static void kthread_init __P((const void *dummy));
556 SYSINIT_KP(init,SI_SUB_KTHREAD_INIT, SI_ORDER_FIRST, kthread_init, NULL)
557 
558 
559 extern void prepare_usermode __P((void));
560 static void start_init __P((struct proc *p));
561 
562 /* ARGSUSED*/
563 static void
564 kthread_init(dummy)
565 	const void *dummy;
566 {
567 	/* Create process 1 (init(8)). */
568 	start_init(curproc);
569 
570 	prepare_usermode();
571 
572 	/*
573 	 * This returns to the fork trampoline, then to user mode.
574 	 */
575 	return;
576 }
577 
578 
579 /*
580  * List of paths to try when searching for "init".
581  */
582 static char init_path[MAXPATHLEN] =
583 #ifdef	INIT_PATH
584     __XSTRING(INIT_PATH);
585 #else
586     "/sbin/init:/sbin/oinit:/sbin/init.bak:/stand/sysinstall";
587 #endif
588 SYSCTL_STRING(_kern, OID_AUTO, init_path, CTLFLAG_RD, init_path, 0, "");
589 
590 /*
591  * Start the initial user process; try exec'ing each pathname in init_path.
592  * The program is invoked with one argument containing the boot flags.
593  */
594 static void
595 start_init(p)
596 	struct proc *p;
597 {
598 	vm_offset_t addr;
599 	struct execve_args args;
600 	int options, error;
601 	char *var, *path, *next, *s;
602 	char *ucp, **uap, *arg0, *arg1;
603 
604 	initproc = p;
605 
606 	/*
607 	 * Need just enough stack to hold the faked-up "execve()" arguments.
608 	 */
609 	addr = trunc_page(USRSTACK - PAGE_SIZE);
610 	if (vm_map_find(&p->p_vmspace->vm_map, NULL, 0, &addr, PAGE_SIZE,
611 			FALSE, VM_PROT_ALL, VM_PROT_ALL, 0) != 0)
612 		panic("init: couldn't allocate argument space");
613 	p->p_vmspace->vm_maxsaddr = (caddr_t)addr;
614 	p->p_vmspace->vm_ssize = 1;
615 
616 	if ((var = getenv("init_path")) != NULL) {
617 		strncpy(init_path, var, sizeof init_path);
618 		init_path[sizeof init_path - 1] = 0;
619 	}
620 
621 	for (path = init_path; *path != '\0'; path = next) {
622 		while (*path == ':')
623 			path++;
624 		if (*path == '\0')
625 			break;
626 		for (next = path; *next != '\0' && *next != ':'; next++)
627 			/* nothing */ ;
628 		if (bootverbose)
629 			printf("start_init: trying %.*s\n", (int)(next - path),
630 			    path);
631 
632 		/*
633 		 * Move out the boot flag argument.
634 		 */
635 		options = 0;
636 		ucp = (char *)USRSTACK;
637 		(void)subyte(--ucp, 0);		/* trailing zero */
638 		if (boothowto & RB_SINGLE) {
639 			(void)subyte(--ucp, 's');
640 			options = 1;
641 		}
642 #ifdef notyet
643                 if (boothowto & RB_FASTBOOT) {
644 			(void)subyte(--ucp, 'f');
645 			options = 1;
646 		}
647 #endif
648 
649 #ifdef BOOTCDROM
650 		(void)subyte(--ucp, 'C');
651 		options = 1;
652 #endif
653 		if (options == 0)
654 			(void)subyte(--ucp, '-');
655 		(void)subyte(--ucp, '-');		/* leading hyphen */
656 		arg1 = ucp;
657 
658 		/*
659 		 * Move out the file name (also arg 0).
660 		 */
661 		(void)subyte(--ucp, 0);
662 		for (s = next - 1; s >= path; s--)
663 			(void)subyte(--ucp, *s);
664 		arg0 = ucp;
665 
666 		/*
667 		 * Move out the arg pointers.
668 		 */
669 		uap = (char **)((intptr_t)ucp & ~(sizeof(intptr_t)-1));
670 		(void)suword((caddr_t)--uap, (long)0);	/* terminator */
671 		(void)suword((caddr_t)--uap, (long)(intptr_t)arg1);
672 		(void)suword((caddr_t)--uap, (long)(intptr_t)arg0);
673 
674 		/*
675 		 * Point at the arguments.
676 		 */
677 		args.fname = arg0;
678 		args.argv = uap;
679 		args.envv = NULL;
680 
681 		/*
682 		 * Now try to exec the program.  If can't for any reason
683 		 * other than it doesn't exist, complain.
684 		 *
685 		 * Otherwise return to mi_startup() which returns to btext
686 		 * which completes the system startup.
687 		 */
688 		if ((error = execve(p, &args)) == 0)
689 			return;
690 		if (error != ENOENT)
691 			printf("exec %.*s: error %d\n", (int)(next - path),
692 			    path, error);
693 	}
694 	printf("init: not found\n");
695 	panic("no init");
696 }
697