xref: /original-bsd/sys/tahoe/tahoe/machdep.c (revision 1364b7d2)
1 /*
2  * Copyright (c) 1982,1987,1988 Regents of the University of California.
3  * All rights reserved.  The Berkeley software License Agreement
4  * specifies the terms and conditions for redistribution.
5  *
6  *	@(#)machdep.c	7.3 (Berkeley) 07/05/89
7  */
8 
9 #include "param.h"
10 #include "systm.h"
11 #include "user.h"
12 #include "kernel.h"
13 #include "map.h"
14 #include "vm.h"
15 #include "proc.h"
16 #include "buf.h"
17 #include "reboot.h"
18 #include "conf.h"
19 #include "vnode.h"
20 #include "../ufs/inode.h"
21 #ifdef NFS
22 #include "mount.h"
23 #include "../nfs/nfsnode.h"
24 #endif /* NFS */
25 #include "file.h"
26 #include "text.h"
27 #include "clist.h"
28 #include "callout.h"
29 #include "cmap.h"
30 #include "malloc.h"
31 #include "mbuf.h"
32 #include "msgbuf.h"
33 #include "../ufs/quota.h"
34 
35 #include "cpu.h"
36 #include "reg.h"
37 #include "pte.h"
38 #include "psl.h"
39 #include "mem.h"
40 #include "mtpr.h"
41 #include "cp.h"
42 
43 #include "../tahoevba/vbavar.h"
44 
45 /*
46  * Declare these as initialized data so we can patch them.
47  */
48 int	nswbuf = 0;
49 #ifdef	NBUF
50 int	nbuf = NBUF;
51 #else
52 int	nbuf = 0;
53 #endif
54 #ifdef	BUFPAGES
55 int	bufpages = BUFPAGES;
56 #else
57 int	bufpages = 0;
58 #endif
59 #include "yc.h"
60 #if NCY > 0
61 #include "../tahoevba/cyreg.h"
62 #endif
63 int	msgbufmapped;		/* set when safe to use msgbuf */
64 
65 /*
66  * Machine-dependent startup code
67  */
68 startup(firstaddr)
69 	int firstaddr;
70 {
71 	register int unixsize;
72 	register unsigned i;
73 	register struct pte *pte;
74 	int mapaddr, j;
75 	register caddr_t v;
76 	int maxbufs, base, residual;
77 
78 	/*
79 	 * Initialize error message buffer (at end of core).
80 	 */
81 	maxmem -= btoc(sizeof (struct msgbuf));
82 	pte = msgbufmap;
83 	for (i = 0; i < btoc(sizeof (struct msgbuf)); i++)
84 		*(int *)pte++ = PG_V | PG_KW | (maxmem + i);
85 	mtpr(TBIA, 1);
86 	msgbufmapped = 1;
87 #ifdef KADB
88 	kdb_init();			/* startup kernel debugger */
89 #endif
90 	/*
91 	 * Good {morning,afternoon,evening,night}.
92 	 */
93 	printf(version);
94 	printf("real mem  = %d\n", ctob(physmem));
95 
96 	/*
97 	 * Allocate space for system data structures.
98 	 * The first available real memory address is in "firstaddr".
99 	 * The first available kernel virtual address is in "v".
100 	 * As pages of kernel virtual memory are allocated, "v" is incremented.
101 	 * As pages of memory are allocated and cleared,
102 	 * "firstaddr" is incremented.
103 	 * An index into the kernel page table corresponding to the
104 	 * virtual memory address maintained in "v" is kept in "mapaddr".
105 	 */
106 	v = (caddr_t)(0xc0000000 | (firstaddr * NBPG));
107 #define	valloc(name, type, num) \
108 	    (name) = (type *)v; v = (caddr_t)((name)+(num))
109 #define	valloclim(name, type, num, lim) \
110 	    (name) = (type *)v; v = (caddr_t)((lim) = ((name)+(num)))
111 #if NCY > 0
112 	/*
113 	 * Allocate raw buffers for tapemaster controllers
114 	 * first, as they need buffers in the first megabyte.
115 	 */
116 	valloc(cybuf, char, NCY * CYMAXIO);
117 #endif
118 	valloclim(inode, struct inode, ninode, inodeNINODE);
119 #ifdef NFS
120 	valloclim(nfsnode, struct nfsnode, nnfsnode, nfsnodeNNFSNODE);
121 #endif /* NFS */
122 	valloclim(file, struct file, nfile, fileNFILE);
123 	valloclim(proc, struct proc, nproc, procNPROC);
124 	valloclim(text, struct text, ntext, textNTEXT);
125 	valloc(cfree, struct cblock, nclist);
126 	valloc(callout, struct callout, ncallout);
127 	valloc(swapmap, struct map, nswapmap = nproc * 2);
128 	valloc(argmap, struct map, ARGMAPSIZE);
129 	valloc(kernelmap, struct map, nproc);
130 	valloc(mbmap, struct map, nmbclusters/4);
131 	valloc(namecache, struct namecache, nchsize);
132 	valloc(kmemmap, struct map, ekmempt - kmempt);
133 	valloc(kmemusage, struct kmemusage, ekmempt - kmempt);
134 #ifdef QUOTA
135 	valloclim(quota, struct quota, nquota, quotaNQUOTA);
136 	valloclim(dquot, struct dquot, ndquot, dquotNDQUOT);
137 #endif
138 
139 	/*
140 	 * Determine how many buffers to allocate.
141 	 * Use 10% of memory for the first 2 Meg, 5% of the remaining
142 	 * memory. Insure a minimum of 16 buffers.
143 	 * We allocate 1/2 as many swap buffer headers as file i/o buffers.
144 	 */
145 	if (bufpages == 0)
146 		if (physmem < (2 * 1024 * 1024))
147 			bufpages = physmem / 10 / CLSIZE;
148 		else
149 			bufpages = ((2 * 1024 * 1024 + physmem) / 20) / CLSIZE;
150 	if (nbuf == 0) {
151 		nbuf = bufpages / 2;
152 		if (nbuf < 16)
153 			nbuf = 16;
154 	}
155 	if (nswbuf == 0) {
156 		nswbuf = (nbuf / 2) &~ 1;	/* force even */
157 		if (nswbuf > 256)
158 			nswbuf = 256;		/* sanity */
159 	}
160 	valloc(swbuf, struct buf, nswbuf);
161 
162 	/*
163 	 * Now the amount of virtual memory remaining for buffers
164 	 * can be calculated, estimating needs for the cmap.
165 	 */
166 	ncmap = (maxmem*NBPG - ((int)v &~ 0xc0000000)) /
167 		(CLBYTES + sizeof(struct cmap)) + 2;
168 	maxbufs = ((SYSPTSIZE * NBPG) -
169 	    ((int)(v + ncmap * sizeof(struct cmap)) - 0xc0000000)) /
170 		(MAXBSIZE + sizeof(struct buf));
171 	if (maxbufs < 16)
172 		panic("sys pt too small");
173 	if (nbuf > maxbufs) {
174 		printf("SYSPTSIZE limits number of buffers to %d\n", maxbufs);
175 		nbuf = maxbufs;
176 	}
177 	if (bufpages > nbuf * (MAXBSIZE / CLBYTES))
178 		bufpages = nbuf * (MAXBSIZE / CLBYTES);
179 	valloc(buf, struct buf, nbuf);
180 
181 	/*
182 	 * Allocate space for core map.
183 	 * Allow space for all of phsical memory minus the amount
184 	 * dedicated to the system. The amount of physical memory
185 	 * dedicated to the system is the total virtual memory of
186 	 * the system thus far, plus core map, buffer pages,
187 	 * and buffer headers not yet allocated.
188 	 * Add 2: 1 because the 0th entry is unused, 1 for rounding.
189 	 */
190 	ncmap = (maxmem*NBPG - ((int)(v + bufpages*CLBYTES) &~ 0xc0000000)) /
191 		(CLBYTES + sizeof(struct cmap)) + 2;
192 	valloclim(cmap, struct cmap, ncmap, ecmap);
193 
194 	/*
195 	 * Clear space allocated thus far, and make r/w entries
196 	 * for the space in the kernel map.
197 	 */
198 	unixsize = btoc((int)v &~ 0xc0000000);
199 	while (firstaddr < unixsize) {
200 		*(int *)(&Sysmap[firstaddr]) = PG_V | PG_KW | firstaddr;
201 		clearseg((unsigned)firstaddr);
202 		firstaddr++;
203 	}
204 
205 	/*
206 	 * Now allocate buffers proper.  They are different than the above
207 	 * in that they usually occupy more virtual memory than physical.
208 	 */
209 	v = (caddr_t) ((int)(v + PGOFSET) &~ PGOFSET);
210 	valloc(buffers, char, MAXBSIZE * nbuf);
211 	base = bufpages / nbuf;
212 	residual = bufpages % nbuf;
213 	mapaddr = firstaddr;
214 	for (i = 0; i < residual; i++) {
215 		for (j = 0; j < (base + 1) * CLSIZE; j++) {
216 			*(int *)(&Sysmap[mapaddr+j]) = PG_V | PG_KW | firstaddr;
217 			clearseg((unsigned)firstaddr);
218 			firstaddr++;
219 		}
220 		mapaddr += MAXBSIZE / NBPG;
221 	}
222 	for (i = residual; i < nbuf; i++) {
223 		for (j = 0; j < base * CLSIZE; j++) {
224 			*(int *)(&Sysmap[mapaddr+j]) = PG_V | PG_KW | firstaddr;
225 			clearseg((unsigned)firstaddr);
226 			firstaddr++;
227 		}
228 		mapaddr += MAXBSIZE / NBPG;
229 	}
230 
231 	unixsize = btoc((int)v &~ 0xc0000000);
232 	if (firstaddr >= physmem - 8*UPAGES)
233 		panic("no memory");
234 	mtpr(TBIA, 1);			/* After we just cleared it all! */
235 
236 	/*
237 	 * Initialize callouts
238 	 */
239 	callfree = callout;
240 	for (i = 1; i < ncallout; i++)
241 		callout[i-1].c_next = &callout[i];
242 
243 	/*
244 	 * Initialize memory allocator and swap
245 	 * and user page table maps.
246 	 *
247 	 * THE USER PAGE TABLE MAP IS CALLED ``kernelmap''
248 	 * WHICH IS A VERY UNDESCRIPTIVE AND INCONSISTENT NAME.
249 	 */
250 	meminit(firstaddr, maxmem);
251 	maxmem = freemem;
252 	printf("avail mem = %d\n", ctob(maxmem));
253 	printf("using %d buffers containing %d bytes of memory\n",
254 		nbuf, bufpages * CLBYTES);
255 	rminit(kernelmap, (long)USRPTSIZE, (long)1,
256 	    "usrpt", nproc);
257 	rminit(mbmap, (long)(nmbclusters * CLSIZE), (long)CLSIZE,
258 	    "mbclusters", nmbclusters/4);
259 	kmeminit();		/* now safe to do malloc/free */
260 	intenable = 1;		/* Enable interrupts from now on */
261 
262 	/*
263 	 * Set up CPU-specific registers, cache, etc.
264 	 */
265 	initcpu();
266 
267 	/*
268 	 * Set up buffers, so they can be used to read disk labels.
269 	 */
270 	bhinit();
271 	binit();
272 
273 	/*
274 	 * Configure the system.
275 	 */
276 	configure();
277 }
278 
279 #ifdef PGINPROF
280 /*
281  * Return the difference (in microseconds)
282  * between the  current time and a previous
283  * time as represented  by the arguments.
284  * If there is a pending clock interrupt
285  * which has not been serviced due to high
286  * ipl, return error code.
287  */
288 /*ARGSUSED*/
289 vmtime(otime, olbolt, oicr)
290 	register int otime, olbolt, oicr;
291 {
292 
293 	return (((time.tv_sec-otime)*60 + lbolt-olbolt)*16667);
294 }
295 #endif
296 
297 /*
298  * Send an interrupt to process.
299  *
300  * Stack is set up to allow sigcode stored
301  * in u. to call routine, followed by kcall
302  * to sigreturn routine below.  After sigreturn
303  * resets the signal mask, the stack, and the
304  * frame pointer, it returns to the user
305  * specified pc, psl.
306  */
307 sendsig(p, sig, mask)
308 	int (*p)(), sig, mask;
309 {
310 	register struct sigcontext *scp;
311 	register int *regs;
312 	register struct sigframe {
313 		int	sf_signum;
314 		int	sf_code;
315 		struct	sigcontext *sf_scp;
316 		int	(*sf_handler)();
317 		int	sf_regs[6];		/* r0-r5 */
318 		struct	sigcontext *sf_scpcopy;
319 	} *fp;
320 	int oonstack;
321 
322 	regs = u.u_ar0;
323 	oonstack = u.u_onstack;
324 	/*
325 	 * Allocate and validate space for the signal handler
326 	 * context. Note that if the stack is in P0 space, the
327 	 * call to grow() is a nop, and the useracc() check
328 	 * will fail if the process has not already allocated
329 	 * the space with a `brk'.
330 	 */
331 	if (!u.u_onstack && (u.u_sigonstack & sigmask(sig))) {
332 		scp = (struct sigcontext *)u.u_sigsp - 1;
333 		u.u_onstack = 1;
334 	} else
335 		scp = (struct sigcontext *)regs[SP] - 1;
336 	fp = (struct sigframe *)scp - 1;
337 	if ((int)fp <= USRSTACK - ctob(u.u_ssize))
338 		(void) grow((unsigned)fp);
339 	if (useracc((caddr_t)fp, sizeof (*fp) + sizeof (*scp), B_WRITE) == 0) {
340 		/*
341 		 * Process has trashed its stack; give it an illegal
342 		 * instruction to halt it in its tracks.
343 		 */
344 		u.u_signal[SIGILL] = SIG_DFL;
345 		sig = sigmask(SIGILL);
346 		u.u_procp->p_sigignore &= ~sig;
347 		u.u_procp->p_sigcatch &= ~sig;
348 		u.u_procp->p_sigmask &= ~sig;
349 		psignal(u.u_procp, SIGILL);
350 		return;
351 	}
352 	/*
353 	 * Build the argument list for the signal handler.
354 	 */
355 	fp->sf_signum = sig;
356 	if (sig == SIGILL || sig == SIGFPE) {
357 		fp->sf_code = u.u_code;
358 		u.u_code = 0;
359 	} else
360 		fp->sf_code = 0;
361 	fp->sf_scp = scp;
362 	fp->sf_handler = p;
363 	/*
364 	 * Build the callf argument frame to be used to call sigreturn.
365 	 */
366 	fp->sf_scpcopy = scp;
367 	/*
368 	 * Build the signal context to be used by sigreturn.
369 	 */
370 	scp->sc_onstack = oonstack;
371 	scp->sc_mask = mask;
372 	scp->sc_sp = regs[SP];
373 	scp->sc_fp = regs[FP];
374 	scp->sc_pc = regs[PC];
375 	scp->sc_ps = regs[PS];
376 	regs[SP] = (int)fp;
377 	regs[PC] = (int)u.u_pcb.pcb_sigc;
378 }
379 
380 /*
381  * System call to cleanup state after a signal
382  * has been taken.  Reset signal mask and
383  * stack state from context left by sendsig (above).
384  * Return to previous pc and psl as specified by
385  * context left by sendsig. Check carefully to
386  * make sure that the user has not modified the
387  * psl to gain improper priviledges or to cause
388  * a machine fault.
389  */
390 sigreturn()
391 {
392 	struct a {
393 		struct sigcontext *sigcntxp;
394 	};
395 	register struct sigcontext *scp;
396 	register int *regs = u.u_ar0;
397 
398 	scp = ((struct a *)(u.u_ap))->sigcntxp;
399 	if (useracc((caddr_t)scp, sizeof (*scp), 0) == 0) {
400 		u.u_error = EINVAL;
401 		return;
402 	}
403 	if ((scp->sc_ps & (PSL_MBZ|PSL_IPL|PSL_IS)) != 0 ||
404 	    (scp->sc_ps & (PSL_PRVMOD|PSL_CURMOD)) != (PSL_PRVMOD|PSL_CURMOD)) {
405 		u.u_error = EINVAL;
406 		return;
407 	}
408 	u.u_eosys = JUSTRETURN;
409 	u.u_onstack = scp->sc_onstack & 01;
410 	u.u_procp->p_sigmask = scp->sc_mask &~
411 	    (sigmask(SIGKILL)|sigmask(SIGCONT)|sigmask(SIGSTOP));
412 	regs[FP] = scp->sc_fp;
413 	regs[SP] = scp->sc_sp;
414 	regs[PC] = scp->sc_pc;
415 	regs[PS] = scp->sc_ps;
416 }
417 
418 /* XXX - BEGIN 4.2 COMPATIBILITY */
419 /*
420  * Compatibility with 4.2 kcall $139 used by longjmp()
421  */
422 osigcleanup()
423 {
424 	register struct sigcontext *scp;
425 	register int *regs = u.u_ar0;
426 
427 	scp = (struct sigcontext *)fuword((caddr_t)regs[SP]);
428 	if ((int)scp == -1)
429 		return;
430 	if (useracc((caddr_t)scp, 3 * sizeof (int), 0) == 0)
431 		return;
432 	u.u_onstack = scp->sc_onstack & 01;
433 	u.u_procp->p_sigmask = scp->sc_mask &~
434 	    (sigmask(SIGKILL)|sigmask(SIGCONT)|sigmask(SIGSTOP));
435 	regs[SP] = scp->sc_sp;
436 }
437 /* XXX - END 4.2 COMPATIBILITY */
438 
439 int	waittime = -1;
440 
441 boot(arghowto)
442 	int arghowto;
443 {
444 	register long dummy;		/* r12 is reserved */
445 	register int howto;		/* r11 == how to boot */
446 	register int devtype;		/* r10 == major of root dev */
447 	extern char *panicstr;
448 
449 	howto = arghowto;
450 	if ((howto&RB_NOSYNC) == 0 && waittime < 0 && bfreelist[0].b_forw) {
451 		register struct buf *bp;
452 		int iter, nbusy;
453 
454 		waittime = 0;
455 		(void) splnet();
456 		printf("syncing disks... ");
457 		/*
458 		 * Release inodes held by texts before update.
459 		 */
460 		if (panicstr == 0)
461 			xumount(NULL);
462 		sync();
463 
464 		for (iter = 0; iter < 20; iter++) {
465 			nbusy = 0;
466 			for (bp = &buf[nbuf]; --bp >= buf; )
467 				if ((bp->b_flags & (B_BUSY|B_INVAL)) == B_BUSY)
468 					nbusy++;
469 			if (nbusy == 0)
470 				break;
471 			printf("%d ", nbusy);
472 			DELAY(40000 * iter);
473 		}
474 		if (nbusy)
475 			printf("giving up\n");
476 		else
477 			printf("done\n");
478 		DELAY(10000);			/* wait for printf to finish */
479 	}
480 	mtpr(IPL, 0x1f);			/* extreme priority */
481 	devtype = major(rootdev);
482 	*(int *)CPBFLG = howto;
483 	if (howto&RB_HALT) {
484 		printf("halting (in tight loop); hit ~h\n\n");
485 		mtpr(IPL, 0x1f);
486 		for (;;)
487 			;
488 	} else {
489 		if (howto & RB_DUMP) {
490 			doadump();		/* CPBOOT's itsself */
491 			/*NOTREACHED*/
492 		}
493 		tocons(CPBOOT);
494 	}
495 #ifdef lint
496 	dummy = 0; dummy = dummy;
497 	printf("howto %d, devtype %d\n", arghowto, devtype);
498 #endif
499 	for (;;)
500 		asm("halt");
501 	/*NOTREACHED*/
502 }
503 
504 struct	cpdcb_o cpcontrol;
505 
506 /*
507  * Send the given comand ('c') to the console processor.
508  * Assumed to be one of the last things the OS does before
509  *  halting or rebooting.
510  */
511 tocons(c)
512 {
513 	register timeout;
514 
515 	cpcontrol.cp_hdr.cp_unit = CPUNIT;
516 	cpcontrol.cp_hdr.cp_comm =  (char)c;
517 	if (c != CPBOOT)
518 		cpcontrol.cp_hdr.cp_count = 1;	/* Just for sanity */
519 	else {
520 		cpcontrol.cp_hdr.cp_count = 4;
521 		*(int *)cpcontrol.cp_buf = 0;	/* r11 value for reboot */
522 	}
523 	timeout = 100000;				/* Delay loop */
524 	while (timeout-- && (cnlast->cp_unit&CPDONE) == 0)
525 		uncache(&cnlast->cp_unit);
526 	/* give up, force it to listen */
527 	mtpr(CPMDCB, vtoph((struct proc *)0, (unsigned)&cpcontrol));
528 }
529 
530 #if CLSIZE != 1
531 /*
532  * Invalidate single all pte's in a cluster
533  */
534 tbiscl(v)
535 	unsigned v;
536 {
537 	register caddr_t addr;		/* must be first reg var */
538 	register int i;
539 
540 	addr = ptob(v);
541 	for (i = 0; i < CLSIZE; i++) {
542 		mtpr(TBIS, addr);
543 		addr += NBPG;
544 	}
545 }
546 #endif
547 
548 int	dumpmag = 0x8fca0101;	/* magic number for savecore */
549 int	dumpsize = 0;		/* also for savecore */
550 /*
551  * Doadump comes here after turning off memory management and
552  * getting on the dump stack, either when called above, or by
553  * the auto-restart code.
554  */
555 dumpsys()
556 {
557 
558 	if (dumpdev == NODEV)
559 		return;
560 #ifdef notdef
561 	if ((minor(dumpdev)&07) != 1)
562 		return;
563 #endif
564 	dumpsize = physmem;
565 	printf("\ndumping to dev %x, offset %d\n", dumpdev, dumplo);
566 	printf("dump ");
567 	switch ((*bdevsw[major(dumpdev)].d_dump)(dumpdev)) {
568 
569 	case ENXIO:
570 		printf("device bad\n");
571 		break;
572 
573 	case EFAULT:
574 		printf("device not ready\n");
575 		break;
576 
577 	case EINVAL:
578 		printf("area improper\n");
579 		break;
580 
581 	case EIO:
582 		printf("i/o error\n");
583 		break;
584 
585 	default:
586 		printf("succeeded\n");
587 		break;
588 	}
589 	printf("\n\n");
590 	DELAY(1000);
591 	tocons(CPBOOT);
592 }
593 
594 /*
595  * Bus error 'recovery' code.
596  * Print out the buss frame and then give up.
597  * (More information from special registers can be printed here.)
598  */
599 
600 /*
601  * Frame for bus error
602  */
603 struct buserframe {
604 	int	which_bus;		/* primary or secondary */
605 	int	memerreg;		/* memory error register */
606 	int	trp_pc;			/* trapped pc */
607 	int	trp_psl;		/* trapped psl */
608 };
609 
610 char	*mem_errcd[8] = {
611 	"Unknown error code 0",
612 	"Address parity error",		/* APE */
613 	"Data parity error",		/* DPE */
614 	"Data check error",		/* DCE */
615 	"Versabus timeout",		/* VTO */
616 	"Versabus error",		/* VBE */
617 	"Non-existent memory",		/* NEM */
618 	"Unknown error code 7",
619 };
620 
621 buserror(v)
622 	caddr_t v;
623 {
624 	register struct buserframe *busef = (struct buserframe *)v;
625 	register long reg;
626 
627 	printf("bus error, address %x, psl %x\n",
628 	    busef->trp_pc, busef->trp_psl);
629 	reg =  busef->memerreg;
630 	printf("mear %x %s\n",
631 	    ((reg&MEAR)>>16)&0xffff, mem_errcd[reg & ERRCD]);
632 	if (reg&AXE)
633 		printf("adapter external error\n");
634 	printf("error master: %s\n", reg&ERM ? "versabus" : "tahoe");
635 	if (reg&IVV)
636 		printf("illegal interrupt vector from ipl %d\n", (reg>>2)&7);
637 	reg = busef->which_bus;
638 	printf("mcbr %x versabus type %x\n",
639 	    ((reg&MCBR)>>16)&0xffff, reg & 0xffc3);
640 	if ((busef->memerreg&IVV) == 0)
641 		panic("buserror");
642 }
643 
644 microtime(tvp)
645 	register struct timeval *tvp;
646 {
647 	int s = splhigh();
648 
649 	*tvp = time;
650 	tvp->tv_usec += tick;
651 	while (tvp->tv_usec > 1000000) {
652 		tvp->tv_sec++;
653 		tvp->tv_usec -= 1000000;
654 	}
655 	splx(s);
656 }
657 
658 initcpu()
659 {
660 	register struct proc *p;
661 
662 	p = &proc[0];
663 #define	initkey(which, p, index) \
664     which/**/_cache[index] = 1, which/**/_cnt[index] = 1; \
665     p->p_/**/which = index;
666 	initkey(ckey, p, MAXCKEY);
667 	initkey(dkey, p, MAXDKEY);
668 }
669 
670 /*
671  * Clear registers on exec
672  */
673 setregs(entry)
674 	u_long entry;
675 {
676 
677 #ifdef notdef
678 	/* should pass args to init on the stack */
679 	for (rp = &u.u_ar0[0]; rp < &u.u_ar0[16];)
680 		*rp++ = 0;
681 #endif
682 	u.u_ar0[FP] = 0;	/* bottom of the fp chain */
683 	u.u_ar0[PC] = entry + 2;
684 }
685