xref: /freebsd/sys/i386/i386/bios.c (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 1997 Michael Smith
5  * Copyright (c) 1998 Jonathan Lemon
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 /*
34  * Code for dealing with the BIOS in x86 PC systems.
35  */
36 
37 #include "opt_isa.h"
38 
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/module.h>
44 #include <sys/bus.h>
45 #include <sys/pcpu.h>
46 #include <vm/vm.h>
47 #include <vm/pmap.h>
48 #include <machine/md_var.h>
49 #include <machine/segments.h>
50 #include <machine/stdarg.h>
51 #include <machine/vmparam.h>
52 #include <machine/pc/bios.h>
53 #ifdef DEV_ISA
54 #include <isa/isavar.h>
55 #include <isa/pnpreg.h>
56 #include <isa/pnpvar.h>
57 #endif
58 
59 #define BIOS_START	0xe0000
60 #define BIOS_SIZE	0x20000
61 
62 /* exported lookup results */
63 struct bios32_SDentry		PCIbios;
64 
65 static struct PnPBIOS_table	*PnPBIOStable;
66 
67 static u_int			bios32_SDCI;
68 
69 /* start fairly early */
70 static void			bios32_init(void *junk);
71 SYSINIT(bios32, SI_SUB_CPU, SI_ORDER_ANY, bios32_init, NULL);
72 
73 /*
74  * bios32_init
75  *
76  * Locate various bios32 entities.
77  */
78 static void
79 bios32_init(void *junk)
80 {
81     u_long			sigaddr;
82     struct bios32_SDheader	*sdh;
83     struct PnPBIOS_table	*pt;
84     u_int8_t			ck, *cv;
85     int				i;
86     char			*p;
87 
88     /*
89      * BIOS32 Service Directory, PCI BIOS
90      */
91 
92     /* look for the signature */
93     if ((sigaddr = bios_sigsearch(0, "_32_", 4, 16, 0)) != 0) {
94 	/* get a virtual pointer to the structure */
95 	sdh = (struct bios32_SDheader *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
96 	for (cv = (u_int8_t *)sdh, ck = 0, i = 0; i < (sdh->len * 16); i++) {
97 	    ck += cv[i];
98 	}
99 	/* If checksum is OK, enable use of the entrypoint */
100 	if ((ck == 0) && (BIOS_START <= sdh->entry ) &&
101 	    (sdh->entry < (BIOS_START + BIOS_SIZE))) {
102 	    bios32_SDCI = BIOS_PADDRTOVADDR(sdh->entry);
103 	    if (bootverbose) {
104 		printf("bios32: Found BIOS32 Service Directory header at %p\n", sdh);
105 		printf("bios32: Entry = 0x%x (%x)  Rev = %d  Len = %d\n",
106 		       sdh->entry, bios32_SDCI, sdh->revision, sdh->len);
107 	    }
108 
109 	    /* Allow user override of PCI BIOS search */
110 	    if (((p = kern_getenv("machdep.bios.pci")) == NULL) || strcmp(p, "disable")) {
111 		/* See if there's a PCI BIOS entrypoint here */
112 		PCIbios.ident.id = 0x49435024;	/* PCI systems should have this */
113 		if (!bios32_SDlookup(&PCIbios) && bootverbose)
114 		    printf("pcibios: PCI BIOS entry at 0x%x+0x%x\n", PCIbios.base, PCIbios.entry);
115 	    }
116 	    if (p != NULL)
117 		    freeenv(p);
118 	} else {
119 	    printf("bios32: Bad BIOS32 Service Directory\n");
120 	}
121     }
122 
123     /*
124      * PnP BIOS
125      *
126      * Allow user override of PnP BIOS search
127      */
128     if ((((p = kern_getenv("machdep.bios.pnp")) == NULL) || strcmp(p, "disable")) &&
129 	((sigaddr = bios_sigsearch(0, "$PnP", 4, 16, 0)) != 0)) {
130 	/* get a virtual pointer to the structure */
131 	pt = (struct PnPBIOS_table *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
132 	for (cv = (u_int8_t *)pt, ck = 0, i = 0; i < pt->len; i++) {
133 	    ck += cv[i];
134 	}
135 	/* If checksum is OK, enable use of the entrypoint */
136 	if (ck == 0) {
137 	    PnPBIOStable = pt;
138 	    if (bootverbose) {
139 		printf("pnpbios: Found PnP BIOS data at %p\n", pt);
140 		printf("pnpbios: Entry = %x:%x  Rev = %d.%d\n",
141 		       pt->pmentrybase, pt->pmentryoffset, pt->version >> 4, pt->version & 0xf);
142 		if ((pt->control & 0x3) == 0x01)
143 		    printf("pnpbios: Event flag at %x\n", pt->evflagaddr);
144 		if (pt->oemdevid != 0)
145 		    printf("pnpbios: OEM ID %x\n", pt->oemdevid);
146 
147 	    }
148 	} else {
149 	    printf("pnpbios: Bad PnP BIOS data checksum\n");
150 	}
151     }
152     if (p != NULL)
153 	    freeenv(p);
154     if (bootverbose) {
155 	    /* look for other know signatures */
156 	    printf("Other BIOS signatures found:\n");
157     }
158 }
159 
160 /*
161  * bios32_SDlookup
162  *
163  * Query the BIOS32 Service Directory for the service named in (ent),
164  * returns nonzero if the lookup fails.  The caller must fill in
165  * (ent->ident), the remainder are populated on a successful lookup.
166  */
167 int
168 bios32_SDlookup(struct bios32_SDentry *ent)
169 {
170     struct bios_regs args;
171 
172     if (bios32_SDCI == 0)
173 	return (1);
174 
175     args.eax = ent->ident.id;		/* set up arguments */
176     args.ebx = args.ecx = args.edx = 0;
177     bios32(&args, bios32_SDCI, GSEL(GCODE_SEL, SEL_KPL));
178     if ((args.eax & 0xff) == 0) {	/* success? */
179 	ent->base = args.ebx;
180 	ent->len = args.ecx;
181 	ent->entry = args.edx;
182 	ent->ventry = BIOS_PADDRTOVADDR(ent->base + ent->entry);
183 	return (0);			/* all OK */
184     }
185     return (1);				/* failed */
186 }
187 
188 /*
189  * bios_sigsearch
190  *
191  * Search some or all of the BIOS region for a signature string.
192  *
193  * (start)	Optional offset returned from this function
194  *		(for searching for multiple matches), or NULL
195  *		to start the search from the base of the BIOS.
196  *		Note that this will be a _physical_ address in
197  *		the range 0xe0000 - 0xfffff.
198  * (sig)	is a pointer to the byte(s) of the signature.
199  * (siglen)	number of bytes in the signature.
200  * (paralen)	signature paragraph (alignment) size.
201  * (sigofs)	offset of the signature within the paragraph.
202  *
203  * Returns the _physical_ address of the found signature, 0 if the
204  * signature was not found.
205  */
206 
207 u_int32_t
208 bios_sigsearch(u_int32_t start, u_char *sig, int siglen, int paralen, int sigofs)
209 {
210     u_char	*sp, *end;
211 
212     /* compute the starting address */
213     if ((start >= BIOS_START) && (start <= (BIOS_START + BIOS_SIZE))) {
214 	sp = (char *)BIOS_PADDRTOVADDR(start);
215     } else if (start == 0) {
216 	sp = (char *)BIOS_PADDRTOVADDR(BIOS_START);
217     } else {
218 	return 0;				/* bogus start address */
219     }
220 
221     /* compute the end address */
222     end = (u_char *)BIOS_PADDRTOVADDR(BIOS_START + BIOS_SIZE);
223 
224     /* loop searching */
225     while ((sp + sigofs + siglen) < end) {
226 	/* compare here */
227 	if (!bcmp(sp + sigofs, sig, siglen)) {
228 	    /* convert back to physical address */
229 	    return((u_int32_t)BIOS_VADDRTOPADDR(sp));
230 	}
231 	sp += paralen;
232     }
233     return(0);
234 }
235 
236 /*
237  * do not staticize, used by bioscall.s
238  */
239 union {
240     struct {
241 	u_short	offset;
242 	u_short	segment;
243     } vec16;
244     struct {
245 	u_int	offset;
246 	u_short	segment;
247     } vec32;
248 } bioscall_vector;			/* bios jump vector */
249 
250 void
251 set_bios_selectors(struct bios_segments *seg, int flags)
252 {
253     struct soft_segment_descriptor ssd = {
254 	0,			/* segment base address (overwritten) */
255 	0,			/* length (overwritten) */
256 	SDT_MEMERA,		/* segment type (overwritten) */
257 	0,			/* priority level */
258 	1,			/* descriptor present */
259 	0, 0,
260 	1,			/* descriptor size (overwritten) */
261 	0			/* granularity == byte units */
262     };
263     union descriptor *p_gdt;
264 
265 #ifdef SMP
266     p_gdt = &gdt[PCPU_GET(cpuid) * NGDT];
267 #else
268     p_gdt = gdt;
269 #endif
270 
271     ssd.ssd_base = seg->code32.base;
272     ssd.ssd_limit = seg->code32.limit;
273     ssdtosd(&ssd, &p_gdt[GBIOSCODE32_SEL].sd);
274 
275     ssd.ssd_def32 = 0;
276     if (flags & BIOSCODE_FLAG) {
277 	ssd.ssd_base = seg->code16.base;
278 	ssd.ssd_limit = seg->code16.limit;
279 	ssdtosd(&ssd, &p_gdt[GBIOSCODE16_SEL].sd);
280     }
281 
282     ssd.ssd_type = SDT_MEMRWA;
283     if (flags & BIOSDATA_FLAG) {
284 	ssd.ssd_base = seg->data.base;
285 	ssd.ssd_limit = seg->data.limit;
286 	ssdtosd(&ssd, &p_gdt[GBIOSDATA_SEL].sd);
287     }
288 
289     if (flags & BIOSUTIL_FLAG) {
290 	ssd.ssd_base = seg->util.base;
291 	ssd.ssd_limit = seg->util.limit;
292 	ssdtosd(&ssd, &p_gdt[GBIOSUTIL_SEL].sd);
293     }
294 
295     if (flags & BIOSARGS_FLAG) {
296 	ssd.ssd_base = seg->args.base;
297 	ssd.ssd_limit = seg->args.limit;
298 	ssdtosd(&ssd, &p_gdt[GBIOSARGS_SEL].sd);
299     }
300 }
301 
302 extern int vm86pa;
303 extern u_long vm86phystk;
304 extern void bios16_jmp(void);
305 
306 /*
307  * this routine is really greedy with selectors, and uses 5:
308  *
309  * 32-bit code selector:	to return to kernel
310  * 16-bit code selector:	for running code
311  *        data selector:	for 16-bit data
312  *        util selector:	extra utility selector
313  *        args selector:	to handle pointers
314  *
315  * the util selector is set from the util16 entry in bios16_args, if a
316  * "U" specifier is seen.
317  *
318  * See <machine/pc/bios.h> for description of format specifiers
319  */
320 int
321 bios16(struct bios_args *args, char *fmt, ...)
322 {
323     char	*p, *stack, *stack_top;
324     va_list 	ap;
325     int 	flags = BIOSCODE_FLAG | BIOSDATA_FLAG;
326     u_int 	i, arg_start, arg_end;
327     void	*bios16_pmap_handle;
328     arg_start = 0xffffffff;
329     arg_end = 0;
330 
331     /*
332      * Some BIOS entrypoints attempt to copy the largest-case
333      * argument frame (in order to generalise handling for
334      * different entry types).  If our argument frame is
335      * smaller than this, the BIOS will reach off the top of
336      * our constructed stack segment.  Pad the top of the stack
337      * with some garbage to avoid this.
338      */
339     stack = (caddr_t)PAGE_SIZE - 32;
340 
341     va_start(ap, fmt);
342     for (p = fmt; p && *p; p++) {
343 	switch (*p) {
344 	case 'p':			/* 32-bit pointer */
345 	    i = va_arg(ap, u_int);
346 	    arg_start = min(arg_start, i);
347 	    arg_end = max(arg_end, i);
348 	    flags |= BIOSARGS_FLAG;
349 	    stack -= 4;
350 	    break;
351 
352 	case 'i':			/* 32-bit integer */
353 	    i = va_arg(ap, u_int);
354 	    stack -= 4;
355 	    break;
356 
357 	case 'U':			/* 16-bit selector */
358 	    flags |= BIOSUTIL_FLAG;
359 	    /* FALLTHROUGH */
360 	case 'D':			/* 16-bit selector */
361 	case 'C':			/* 16-bit selector */
362 	    stack -= 2;
363 	    break;
364 
365 	case 's':			/* 16-bit integer passed as an int */
366 	    i = va_arg(ap, int);
367 	    stack -= 2;
368 	    break;
369 
370 	default:
371 	    va_end(ap);
372 	    return (EINVAL);
373 	}
374     }
375     va_end(ap);
376 
377     if (flags & BIOSARGS_FLAG) {
378 	if (arg_end - arg_start > ctob(16))
379 	    return (EACCES);
380 	args->seg.args.base = arg_start;
381 	args->seg.args.limit = 0xffff;
382     }
383 
384     args->seg.code32.base = pmap_pg_frame((u_int)&bios16_jmp);
385     args->seg.code32.limit = 0xffff;
386 
387     bios16_pmap_handle = pmap_bios16_enter();
388 
389     stack_top = stack;
390     va_start(ap, fmt);
391     for (p = fmt; p && *p; p++) {
392 	switch (*p) {
393 	case 'p':			/* 32-bit pointer */
394 	    i = va_arg(ap, u_int);
395 	    *(u_int *)stack = (i - arg_start) |
396 		(GSEL(GBIOSARGS_SEL, SEL_KPL) << 16);
397 	    stack += 4;
398 	    break;
399 
400 	case 'i':			/* 32-bit integer */
401 	    i = va_arg(ap, u_int);
402 	    *(u_int *)stack = i;
403 	    stack += 4;
404 	    break;
405 
406 	case 'U':			/* 16-bit selector */
407 	    *(u_short *)stack = GSEL(GBIOSUTIL_SEL, SEL_KPL);
408 	    stack += 2;
409 	    break;
410 
411 	case 'D':			/* 16-bit selector */
412 	    *(u_short *)stack = GSEL(GBIOSDATA_SEL, SEL_KPL);
413 	    stack += 2;
414 	    break;
415 
416 	case 'C':			/* 16-bit selector */
417 	    *(u_short *)stack = GSEL(GBIOSCODE16_SEL, SEL_KPL);
418 	    stack += 2;
419 	    break;
420 
421 	case 's':			/* 16-bit integer passed as an int */
422 	    i = va_arg(ap, int);
423 	    *(u_short *)stack = i;
424 	    stack += 2;
425 	    break;
426 
427 	default:
428 	    va_end(ap);
429 	    return (EINVAL);
430 	}
431     }
432     va_end(ap);
433 
434     set_bios_selectors(&args->seg, flags);
435     bioscall_vector.vec16.offset = (u_short)args->entry;
436     bioscall_vector.vec16.segment = GSEL(GBIOSCODE16_SEL, SEL_KPL);
437 
438     i = bios16_call(&args->r, stack_top);
439     pmap_bios16_leave(bios16_pmap_handle);
440     return (i);
441 }
442 
443 int
444 bios_oem_strings(struct bios_oem *oem, u_char *buffer, size_t maxlen)
445 {
446 	size_t idx = 0;
447 	struct bios_oem_signature *sig;
448 	u_int from, to;
449 	u_char c, *s, *se, *str, *bios_str;
450 	size_t i, off, len, tot;
451 
452 	if ( !oem || !buffer || maxlen<2 )
453 		return(-1);
454 
455 	sig = oem->signature;
456 	if (!sig)
457 		return(-2);
458 
459 	from = oem->range.from;
460 	to = oem->range.to;
461 	if ( (to<=from) || (from<BIOS_START) || (to>(BIOS_START+BIOS_SIZE)) )
462 		return(-3);
463 
464 	while (sig->anchor != NULL) {
465 		str = sig->anchor;
466 		len = strlen(str);
467 		off = sig->offset;
468 		tot = sig->totlen;
469 		/* make sure offset doesn't go beyond bios area */
470 		if ( (to+off)>(BIOS_START+BIOS_SIZE) ||
471 					((from+off)<BIOS_START) ) {
472 			printf("sys/i386/i386/bios.c: sig '%s' "
473 				"from 0x%0x to 0x%0x offset %d "
474 				"out of BIOS bounds 0x%0x - 0x%0x\n",
475 				str, from, to, off,
476 				BIOS_START, BIOS_START+BIOS_SIZE);
477 			return(-4);
478 		}
479 		/* make sure we don't overrun return buffer */
480 		if (idx + tot > maxlen - 1) {
481 			printf("sys/i386/i386/bios.c: sig '%s' "
482 				"idx %d + tot %d = %d > maxlen-1 %d\n",
483 				str, idx, tot, idx+tot, maxlen-1);
484 			return(-5);
485 		}
486 		bios_str = NULL;
487 		s = (u_char *)BIOS_PADDRTOVADDR(from);
488 		se = (u_char *)BIOS_PADDRTOVADDR(to-len);
489 		for (; s<se; s++) {
490 			if (!bcmp(str, s, len)) {
491 				bios_str = s;
492 				break;
493 			}
494 		}
495 		/*
496 		*  store pretty version of totlen bytes of bios string with
497 		*  given offset; 0x20 - 0x7E are printable; uniquify spaces
498 		*/
499 		if (bios_str) {
500 			for (i=0; i<tot; i++) {
501 				c = bios_str[i+off];
502 				if ( (c < 0x20) || (c > 0x7E) )
503 					c = ' ';
504 				if (idx == 0) {
505 					if (c != ' ')
506 						buffer[idx++] = c;
507 				} else if ( (c != ' ') ||
508 					((c == ' ') && (buffer[idx-1] != ' ')) )
509 						buffer[idx++] = c;
510 			}
511 		}
512 		sig++;
513 	}
514 	/* remove a final trailing space */
515 	if ( (idx > 1) && (buffer[idx-1] == ' ') )
516 		idx--;
517 	buffer[idx] = '\0';
518 	return (idx);
519 }
520 
521 #ifdef DEV_ISA
522 /*
523  * PnP BIOS interface; enumerate devices only known to the system
524  * BIOS and save information about them for later use.
525  */
526 
527 struct pnp_sysdev
528 {
529     u_int16_t	size;
530     u_int8_t	handle;
531     u_int32_t	devid;
532     u_int8_t	type[3];
533     u_int16_t	attrib;
534 #define PNPATTR_NODISABLE	(1<<0)	/* can't be disabled */
535 #define PNPATTR_NOCONFIG	(1<<1)	/* can't be configured */
536 #define PNPATTR_OUTPUT		(1<<2)	/* can be primary output */
537 #define PNPATTR_INPUT		(1<<3)	/* can be primary input */
538 #define PNPATTR_BOOTABLE	(1<<4)	/* can be booted from */
539 #define PNPATTR_DOCK		(1<<5)	/* is a docking station */
540 #define PNPATTR_REMOVEABLE	(1<<6)	/* device is removeable */
541 #define PNPATTR_CONFIG_STATIC	(0)
542 #define PNPATTR_CONFIG_DYNAMIC	(1)
543 #define PNPATTR_CONFIG_DYNONLY	(3)
544 #define PNPATTR_CONFIG(a)	(((a) >> 7) & 0x3)
545     /* device-specific data comes here */
546     u_int8_t	devdata[0];
547 } __packed;
548 
549 /* We have to cluster arguments within a 64k range for the bios16 call */
550 struct pnp_sysdevargs
551 {
552     u_int16_t	next;
553     struct pnp_sysdev node;
554 };
555 
556 /*
557  * This function is called after the bus has assigned resource
558  * locations for a logical device.
559  */
560 static void
561 pnpbios_set_config(void *arg, struct isa_config *config, int enable)
562 {
563 }
564 
565 /*
566  * Quiz the PnP BIOS, build a list of PNP IDs and resource data.
567  */
568 static void
569 pnpbios_identify(driver_t *driver, device_t parent)
570 {
571     struct PnPBIOS_table	*pt = PnPBIOStable;
572     struct bios_args		args;
573     struct pnp_sysdev		*pd;
574     struct pnp_sysdevargs	*pda;
575     u_int16_t			ndevs, bigdev;
576     int				error, currdev;
577     u_int8_t			*devnodebuf, tag;
578     u_int32_t			*devid, *compid;
579     int				idx, left;
580     device_t			dev;
581 
582     /* no PnP BIOS information */
583     if (pt == NULL)
584 	return;
585 
586     /* Check to see if ACPI is already active. */
587     dev = devclass_get_device(devclass_find("acpi"), 0);
588     if (dev != NULL && device_is_attached(dev))
589 	return;
590 
591     /* get count of PnP devices */
592     bzero(&args, sizeof(args));
593     args.seg.code16.base = BIOS_PADDRTOVADDR(pt->pmentrybase);
594     args.seg.code16.limit = 0xffff;		/* XXX ? */
595     args.seg.data.base = BIOS_PADDRTOVADDR(pt->pmdataseg);
596     args.seg.data.limit = 0xffff;
597     args.entry = pt->pmentryoffset;
598 
599     if ((error = bios16(&args, PNP_COUNT_DEVNODES, &ndevs, &bigdev)) || (args.r.eax & 0xff)) {
600 	printf("pnpbios: error %d/%x getting device count/size limit\n", error, args.r.eax);
601 	return;
602     }
603     ndevs &= 0xff;				/* clear high byte garbage */
604     if (bootverbose)
605 	printf("pnpbios: %d devices, largest %d bytes\n", ndevs, bigdev);
606 
607     devnodebuf = malloc(bigdev + (sizeof(struct pnp_sysdevargs) - sizeof(struct pnp_sysdev)),
608 			M_DEVBUF, M_NOWAIT);
609     if (devnodebuf == NULL) {
610 	printf("pnpbios: cannot allocate memory, bailing\n");
611 	return;
612     }
613     pda = (struct pnp_sysdevargs *)devnodebuf;
614     pd = &pda->node;
615 
616     for (currdev = 0, left = ndevs; (currdev != 0xff) && (left > 0); left--) {
617 	bzero(pd, bigdev);
618 	pda->next = currdev;
619 	/* get current configuration */
620 	if ((error = bios16(&args, PNP_GET_DEVNODE, &pda->next, &pda->node, 1))) {
621 	    printf("pnpbios: error %d making BIOS16 call\n", error);
622 	    break;
623 	}
624 	if ((error = (args.r.eax & 0xff))) {
625 	    if (bootverbose)
626 		printf("pnpbios: %s 0x%x fetching node %d\n", error & 0x80 ? "error" : "warning", error, currdev);
627 	    if (error & 0x80)
628 		break;
629 	}
630 	currdev = pda->next;
631 	if (pd->size < sizeof(struct pnp_sysdev)) {
632 	    printf("pnpbios: bogus system node data, aborting scan\n");
633 	    break;
634 	}
635 
636 	/*
637 	 * Ignore PICs so that we don't have to worry about the PICs
638 	 * claiming IRQs to prevent their use.  The PIC drivers
639 	 * already ensure that invalid IRQs are not used.
640 	 */
641 	if (!strcmp(pnp_eisaformat(pd->devid), "PNP0000"))	/* ISA PIC */
642 	    continue;
643 	if (!strcmp(pnp_eisaformat(pd->devid), "PNP0003"))	/* APIC */
644 	    continue;
645 
646 	/* Add the device and parse its resources */
647 	dev = BUS_ADD_CHILD(parent, ISA_ORDER_PNPBIOS, NULL, -1);
648 	isa_set_vendorid(dev, pd->devid);
649 	isa_set_logicalid(dev, pd->devid);
650 	/*
651 	 * It appears that some PnP BIOS doesn't allow us to re-enable
652 	 * the embedded system device once it is disabled.  We shall
653 	 * mark all system device nodes as "cannot be disabled", regardless
654 	 * of actual settings in the device attribute byte.
655 	 * XXX
656 	isa_set_configattr(dev,
657 	    ((pd->attrib & PNPATTR_NODISABLE) ?  0 : ISACFGATTR_CANDISABLE) |
658 	    ((!(pd->attrib & PNPATTR_NOCONFIG) &&
659 		PNPATTR_CONFIG(pd->attrib) != PNPATTR_CONFIG_STATIC)
660 		? ISACFGATTR_DYNAMIC : 0));
661 	 */
662 	isa_set_configattr(dev,
663 	    (!(pd->attrib & PNPATTR_NOCONFIG) &&
664 		PNPATTR_CONFIG(pd->attrib) != PNPATTR_CONFIG_STATIC)
665 		? ISACFGATTR_DYNAMIC : 0);
666 	isa_set_pnpbios_handle(dev, pd->handle);
667 	ISA_SET_CONFIG_CALLBACK(parent, dev, pnpbios_set_config, 0);
668 	pnp_parse_resources(dev, &pd->devdata[0],
669 	    pd->size - sizeof(struct pnp_sysdev), 0);
670 	if (!device_get_desc(dev))
671 	    device_set_desc_copy(dev, pnp_eisaformat(pd->devid));
672 
673 	/* Find device IDs */
674 	devid = &pd->devid;
675 	compid = NULL;
676 
677 	/* look for a compatible device ID too */
678 	left = pd->size - sizeof(struct pnp_sysdev);
679 	idx = 0;
680 	while (idx < left) {
681 	    tag = pd->devdata[idx++];
682 	    if (PNP_RES_TYPE(tag) == 0) {
683 		/* Small resource */
684 		switch (PNP_SRES_NUM(tag)) {
685 		case PNP_TAG_COMPAT_DEVICE:
686 		    compid = (u_int32_t *)(pd->devdata + idx);
687 		    if (bootverbose)
688 			printf("pnpbios: node %d compat ID 0x%08x\n", pd->handle, *compid);
689 		    /* FALLTHROUGH */
690 		case PNP_TAG_END:
691 		    idx = left;
692 		    break;
693 		default:
694 		    idx += PNP_SRES_LEN(tag);
695 		    break;
696 		}
697 	    } else
698 		/* Large resource, skip it */
699 		idx += *(u_int16_t *)(pd->devdata + idx) + 2;
700 	}
701 	if (bootverbose) {
702 	    printf("pnpbios: handle %d device ID %s (%08x)",
703 		   pd->handle, pnp_eisaformat(*devid), *devid);
704 	    if (compid != NULL)
705 		printf(" compat ID %s (%08x)",
706 		       pnp_eisaformat(*compid), *compid);
707 	    printf("\n");
708 	}
709     }
710 }
711 
712 static device_method_t pnpbios_methods[] = {
713 	/* Device interface */
714 	DEVMETHOD(device_identify,	pnpbios_identify),
715 	{ 0, 0 }
716 };
717 
718 static driver_t pnpbios_driver = {
719 	"pnpbios",
720 	pnpbios_methods,
721 	1,			/* no softc */
722 };
723 
724 static devclass_t pnpbios_devclass;
725 
726 DRIVER_MODULE(pnpbios, isa, pnpbios_driver, pnpbios_devclass, 0, 0);
727 #endif /* DEV_ISA */
728