summaryrefslogtreecommitdiffstats
path: root/drivers/acpi/acpica/tbutils.c
blob: 0f2d395feabadb20e8ce47d88f53ff8d786e2427 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
/******************************************************************************
 *
 * Module Name: tbutils   - table utilities
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2011, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <acpi/acpi.h>
#include "accommon.h"
#include "actables.h"

#define _COMPONENT          ACPI_TABLES
ACPI_MODULE_NAME("tbutils")

/* Local prototypes */
static void acpi_tb_fix_string(char *string, acpi_size length);

static void
acpi_tb_cleanup_table_header(struct acpi_table_header *out_header,
			     struct acpi_table_header *header);

static acpi_physical_address
acpi_tb_get_root_table_entry(u8 *table_entry, u32 table_entry_size);

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_check_xsdt
 *
 * PARAMETERS:  address                    - Pointer to the XSDT
 *
 * RETURN:      status
 *		AE_OK - XSDT is okay
 *		AE_NO_MEMORY - can't map XSDT
 *		AE_INVALID_TABLE_LENGTH - invalid table length
 *		AE_NULL_ENTRY - XSDT has NULL entry
 *
 * DESCRIPTION: validate XSDT
******************************************************************************/

static acpi_status
acpi_tb_check_xsdt(acpi_physical_address address)
{
	struct acpi_table_header *table;
	u32 length;
	u64 xsdt_entry_address;
	u8 *table_entry;
	u32 table_count;
	int i;

	table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
	if (!table)
		return AE_NO_MEMORY;

	length = table->length;
	acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
	if (length < sizeof(struct acpi_table_header))
		return AE_INVALID_TABLE_LENGTH;

	table = acpi_os_map_memory(address, length);
	if (!table)
		return AE_NO_MEMORY;

	/* Calculate the number of tables described in XSDT */
	table_count =
		(u32) ((table->length -
		sizeof(struct acpi_table_header)) / sizeof(u64));
	table_entry =
		ACPI_CAST_PTR(u8, table) + sizeof(struct acpi_table_header);
	for (i = 0; i < table_count; i++) {
		ACPI_MOVE_64_TO_64(&xsdt_entry_address, table_entry);
		if (!xsdt_entry_address) {
			/* XSDT has NULL entry */
			break;
		}
		table_entry += sizeof(u64);
	}
	acpi_os_unmap_memory(table, length);

	if (i < table_count)
		return AE_NULL_ENTRY;
	else
		return AE_OK;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_initialize_facs
 *
 * PARAMETERS:  None
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Create a permanent mapping for the FADT and save it in a global
 *              for accessing the Global Lock and Firmware Waking Vector
 *
 ******************************************************************************/

acpi_status acpi_tb_initialize_facs(void)
{
	acpi_status status;

	status = acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
					 ACPI_CAST_INDIRECT_PTR(struct
								acpi_table_header,
								&acpi_gbl_FACS));
	return status;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_tables_loaded
 *
 * PARAMETERS:  None
 *
 * RETURN:      TRUE if required ACPI tables are loaded
 *
 * DESCRIPTION: Determine if the minimum required ACPI tables are present
 *              (FADT, FACS, DSDT)
 *
 ******************************************************************************/

u8 acpi_tb_tables_loaded(void)
{

	if (acpi_gbl_root_table_list.current_table_count >= 3) {
		return (TRUE);
	}

	return (FALSE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_fix_string
 *
 * PARAMETERS:  String              - String to be repaired
 *              Length              - Maximum length
 *
 * RETURN:      None
 *
 * DESCRIPTION: Replace every non-printable or non-ascii byte in the string
 *              with a question mark '?'.
 *
 ******************************************************************************/

static void acpi_tb_fix_string(char *string, acpi_size length)
{

	while (length && *string) {
		if (!ACPI_IS_PRINT(*string)) {
			*string = '?';
		}
		string++;
		length--;
	}
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_cleanup_table_header
 *
 * PARAMETERS:  out_header          - Where the cleaned header is returned
 *              Header              - Input ACPI table header
 *
 * RETURN:      Returns the cleaned header in out_header
 *
 * DESCRIPTION: Copy the table header and ensure that all "string" fields in
 *              the header consist of printable characters.
 *
 ******************************************************************************/

static void
acpi_tb_cleanup_table_header(struct acpi_table_header *out_header,
			     struct acpi_table_header *header)
{

	ACPI_MEMCPY(out_header, header, sizeof(struct acpi_table_header));

	acpi_tb_fix_string(out_header->signature, ACPI_NAME_SIZE);
	acpi_tb_fix_string(out_header->oem_id, ACPI_OEM_ID_SIZE);
	acpi_tb_fix_string(out_header->oem_table_id, ACPI_OEM_TABLE_ID_SIZE);
	acpi_tb_fix_string(out_header->asl_compiler_id, ACPI_NAME_SIZE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_print_table_header
 *
 * PARAMETERS:  Address             - Table physical address
 *              Header              - Table header
 *
 * RETURN:      None
 *
 * DESCRIPTION: Print an ACPI table header. Special cases for FACS and RSDP.
 *
 ******************************************************************************/

void
acpi_tb_print_table_header(acpi_physical_address address,
			   struct acpi_table_header *header)
{
	struct acpi_table_header local_header;

	/*
	 * The reason that the Address is cast to a void pointer is so that we
	 * can use %p which will work properly on both 32-bit and 64-bit hosts.
	 */
	if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_FACS)) {

		/* FACS only has signature and length fields */

		ACPI_INFO((AE_INFO, "%4.4s %p %05X",
			   header->signature, ACPI_CAST_PTR(void, address),
			   header->length));
	} else if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_RSDP)) {

		/* RSDP has no common fields */

		ACPI_MEMCPY(local_header.oem_id,
			    ACPI_CAST_PTR(struct acpi_table_rsdp,
					  header)->oem_id, ACPI_OEM_ID_SIZE);
		acpi_tb_fix_string(local_header.oem_id, ACPI_OEM_ID_SIZE);

		ACPI_INFO((AE_INFO, "RSDP %p %05X (v%.2d %6.6s)",
			   ACPI_CAST_PTR (void, address),
			   (ACPI_CAST_PTR(struct acpi_table_rsdp, header)->
			    revision >
			    0) ? ACPI_CAST_PTR(struct acpi_table_rsdp,
					       header)->length : 20,
			   ACPI_CAST_PTR(struct acpi_table_rsdp,
					 header)->revision,
			   local_header.oem_id));
	} else {
		/* Standard ACPI table with full common header */

		acpi_tb_cleanup_table_header(&local_header, header);

		ACPI_INFO((AE_INFO,
			   "%4.4s %p %05X (v%.2d %6.6s %8.8s %08X %4.4s %08X)",
			   local_header.signature, ACPI_CAST_PTR(void, address),
			   local_header.length, local_header.revision,
			   local_header.oem_id, local_header.oem_table_id,
			   local_header.oem_revision,
			   local_header.asl_compiler_id,
			   local_header.asl_compiler_revision));

	}
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_validate_checksum
 *
 * PARAMETERS:  Table               - ACPI table to verify
 *              Length              - Length of entire table
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Verifies that the table checksums to zero. Optionally returns
 *              exception on bad checksum.
 *
 ******************************************************************************/

acpi_status acpi_tb_verify_checksum(struct acpi_table_header *table, u32 length)
{
	u8 checksum;

	/* Compute the checksum on the table */

	checksum = acpi_tb_checksum(ACPI_CAST_PTR(u8, table), length);

	/* Checksum ok? (should be zero) */

	if (checksum) {
		ACPI_WARNING((AE_INFO,
			      "Incorrect checksum in table [%4.4s] - 0x%2.2X, should be 0x%2.2X",
			      table->signature, table->checksum,
			      (u8) (table->checksum - checksum)));

#if (ACPI_CHECKSUM_ABORT)

		return (AE_BAD_CHECKSUM);
#endif
	}

	return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_checksum
 *
 * PARAMETERS:  Buffer          - Pointer to memory region to be checked
 *              Length          - Length of this memory region
 *
 * RETURN:      Checksum (u8)
 *
 * DESCRIPTION: Calculates circular checksum of memory region.
 *
 ******************************************************************************/

u8 acpi_tb_checksum(u8 *buffer, u32 length)
{
	u8 sum = 0;
	u8 *end = buffer + length;

	while (buffer < end) {
		sum = (u8) (sum + *(buffer++));
	}

	return sum;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_check_dsdt_header
 *
 * PARAMETERS:  None
 *
 * RETURN:      None
 *
 * DESCRIPTION: Quick compare to check validity of the DSDT. This will detect
 *              if the DSDT has been replaced from outside the OS and/or if
 *              the DSDT header has been corrupted.
 *
 ******************************************************************************/

void acpi_tb_check_dsdt_header(void)
{

	/* Compare original length and checksum to current values */

	if (acpi_gbl_original_dsdt_header.length != acpi_gbl_DSDT->length ||
	    acpi_gbl_original_dsdt_header.checksum != acpi_gbl_DSDT->checksum) {
		ACPI_ERROR((AE_INFO,
			    "The DSDT has been corrupted or replaced - old, new headers below"));
		acpi_tb_print_table_header(0, &acpi_gbl_original_dsdt_header);
		acpi_tb_print_table_header(0, acpi_gbl_DSDT);

		ACPI_ERROR((AE_INFO,
			    "Please send DMI info to linux-acpi@vger.kernel.org\n"
			    "If system does not work as expected, please boot with acpi=copy_dsdt"));

		/* Disable further error messages */

		acpi_gbl_original_dsdt_header.length = acpi_gbl_DSDT->length;
		acpi_gbl_original_dsdt_header.checksum =
		    acpi_gbl_DSDT->checksum;
	}
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_copy_dsdt
 *
 * PARAMETERS:  table_desc          - Installed table to copy
 *
 * RETURN:      None
 *
 * DESCRIPTION: Implements a subsystem option to copy the DSDT to local memory.
 *              Some very bad BIOSs are known to either corrupt the DSDT or
 *              install a new, bad DSDT. This copy works around the problem.
 *
 ******************************************************************************/

struct acpi_table_header *acpi_tb_copy_dsdt(u32 table_index)
{
	struct acpi_table_header *new_table;
	struct acpi_table_desc *table_desc;

	table_desc = &acpi_gbl_root_table_list.tables[table_index];

	new_table = ACPI_ALLOCATE(table_desc->length);
	if (!new_table) {
		ACPI_ERROR((AE_INFO, "Could not copy DSDT of length 0x%X",
			    table_desc->length));
		return (NULL);
	}

	ACPI_MEMCPY(new_table, table_desc->pointer, table_desc->length);
	acpi_tb_delete_table(table_desc);
	table_desc->pointer = new_table;
	table_desc->flags = ACPI_TABLE_ORIGIN_ALLOCATED;

	ACPI_INFO((AE_INFO,
		   "Forced DSDT copy: length 0x%05X copied locally, original unmapped",
		   new_table->length));

	return (new_table);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_install_table
 *
 * PARAMETERS:  Address                 - Physical address of DSDT or FACS
 *              Signature               - Table signature, NULL if no need to
 *                                        match
 *              table_index             - Index into root table array
 *
 * RETURN:      None
 *
 * DESCRIPTION: Install an ACPI table into the global data structure. The
 *              table override mechanism is implemented here to allow the host
 *              OS to replace any table before it is installed in the root
 *              table array.
 *
 ******************************************************************************/

void
acpi_tb_install_table(acpi_physical_address address,
		      char *signature, u32 table_index)
{
	u8 flags;
	acpi_status status;
	struct acpi_table_header *table_to_install;
	struct acpi_table_header *mapped_table;
	struct acpi_table_header *override_table = NULL;

	if (!address) {
		ACPI_ERROR((AE_INFO,
			    "Null physical address for ACPI table [%s]",
			    signature));
		return;
	}

	/* Map just the table header */

	mapped_table =
	    acpi_os_map_memory(address, sizeof(struct acpi_table_header));
	if (!mapped_table) {
		return;
	}

	/* If a particular signature is expected (DSDT/FACS), it must match */

	if (signature && !ACPI_COMPARE_NAME(mapped_table->signature, signature)) {
		ACPI_ERROR((AE_INFO,
			    "Invalid signature 0x%X for ACPI table, expected [%s]",
			    *ACPI_CAST_PTR(u32, mapped_table->signature),
			    signature));
		goto unmap_and_exit;
	}

	/*
	 * ACPI Table Override:
	 *
	 * Before we install the table, let the host OS override it with a new
	 * one if desired. Any table within the RSDT/XSDT can be replaced,
	 * including the DSDT which is pointed to by the FADT.
	 */
	status = acpi_os_table_override(mapped_table, &override_table);
	if (ACPI_SUCCESS(status) && override_table) {
		ACPI_INFO((AE_INFO,
			   "%4.4s @ 0x%p Table override, replaced with:",
			   mapped_table->signature, ACPI_CAST_PTR(void,
								  address)));

		acpi_gbl_root_table_list.tables[table_index].pointer =
		    override_table;
		address = ACPI_PTR_TO_PHYSADDR(override_table);

		table_to_install = override_table;
		flags = ACPI_TABLE_ORIGIN_OVERRIDE;
	} else {
		table_to_install = mapped_table;
		flags = ACPI_TABLE_ORIGIN_MAPPED;
	}

	/* Initialize the table entry */

	acpi_gbl_root_table_list.tables[table_index].address = address;
	acpi_gbl_root_table_list.tables[table_index].length =
	    table_to_install->length;
	acpi_gbl_root_table_list.tables[table_index].flags = flags;

	ACPI_MOVE_32_TO_32(&
			   (acpi_gbl_root_table_list.tables[table_index].
			    signature), table_to_install->signature);

	acpi_tb_print_table_header(address, table_to_install);

	if (table_index == ACPI_TABLE_INDEX_DSDT) {

		/* Global integer width is based upon revision of the DSDT */

		acpi_ut_set_integer_width(table_to_install->revision);
	}

      unmap_and_exit:
	acpi_os_unmap_memory(mapped_table, sizeof(struct acpi_table_header));
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_get_root_table_entry
 *
 * PARAMETERS:  table_entry         - Pointer to the RSDT/XSDT table entry
 *              table_entry_size    - sizeof 32 or 64 (RSDT or XSDT)
 *
 * RETURN:      Physical address extracted from the root table
 *
 * DESCRIPTION: Get one root table entry. Handles 32-bit and 64-bit cases on
 *              both 32-bit and 64-bit platforms
 *
 * NOTE:        acpi_physical_address is 32-bit on 32-bit platforms, 64-bit on
 *              64-bit platforms.
 *
 ******************************************************************************/

static acpi_physical_address
acpi_tb_get_root_table_entry(u8 *table_entry, u32 table_entry_size)
{
	u64 address64;

	/*
	 * Get the table physical address (32-bit for RSDT, 64-bit for XSDT):
	 * Note: Addresses are 32-bit aligned (not 64) in both RSDT and XSDT
	 */
	if (table_entry_size == sizeof(u32)) {
		/*
		 * 32-bit platform, RSDT: Return 32-bit table entry
		 * 64-bit platform, RSDT: Expand 32-bit to 64-bit and return
		 */
		return ((acpi_physical_address)
			(*ACPI_CAST_PTR(u32, table_entry)));
	} else {
		/*
		 * 32-bit platform, XSDT: Truncate 64-bit to 32-bit and return
		 * 64-bit platform, XSDT: Move (unaligned) 64-bit to local,
		 *  return 64-bit
		 */
		ACPI_MOVE_64_TO_64(&address64, table_entry);

#if ACPI_MACHINE_WIDTH == 32
		if (address64 > ACPI_UINT32_MAX) {

			/* Will truncate 64-bit address to 32 bits, issue warning */

			ACPI_WARNING((AE_INFO,
				      "64-bit Physical Address in XSDT is too large (0x%8.8X%8.8X),"
				      " truncating",
				      ACPI_FORMAT_UINT64(address64)));
		}
#endif
		return ((acpi_physical_address) (address64));
	}
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_parse_root_table
 *
 * PARAMETERS:  Rsdp                    - Pointer to the RSDP
 *
 * RETURN:      Status
 *
 * DESCRIPTION: This function is called to parse the Root System Description
 *              Table (RSDT or XSDT)
 *
 * NOTE:        Tables are mapped (not copied) for efficiency. The FACS must
 *              be mapped and cannot be copied because it contains the actual
 *              memory location of the ACPI Global Lock.
 *
 ******************************************************************************/

acpi_status __init
acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
{
	struct acpi_table_rsdp *rsdp;
	u32 table_entry_size;
	u32 i;
	u32 table_count;
	struct acpi_table_header *table;
	acpi_physical_address address;
	acpi_physical_address uninitialized_var(rsdt_address);
	u32 length;
	u8 *table_entry;
	acpi_status status;

	ACPI_FUNCTION_TRACE(tb_parse_root_table);

	/*
	 * Map the entire RSDP and extract the address of the RSDT or XSDT
	 */
	rsdp = acpi_os_map_memory(rsdp_address, sizeof(struct acpi_table_rsdp));
	if (!rsdp) {
		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	acpi_tb_print_table_header(rsdp_address,
				   ACPI_CAST_PTR(struct acpi_table_header,
						 rsdp));

	/* Differentiate between RSDT and XSDT root tables */

	if (rsdp->revision > 1 && rsdp->xsdt_physical_address
			&& !acpi_rsdt_forced) {
		/*
		 * Root table is an XSDT (64-bit physical addresses). We must use the
		 * XSDT if the revision is > 1 and the XSDT pointer is present, as per
		 * the ACPI specification.
		 */
		address = (acpi_physical_address) rsdp->xsdt_physical_address;
		table_entry_size = sizeof(u64);
		rsdt_address = (acpi_physical_address)
					rsdp->rsdt_physical_address;
	} else {
		/* Root table is an RSDT (32-bit physical addresses) */

		address = (acpi_physical_address) rsdp->rsdt_physical_address;
		table_entry_size = sizeof(u32);
	}

	/*
	 * It is not possible to map more than one entry in some environments,
	 * so unmap the RSDP here before mapping other tables
	 */
	acpi_os_unmap_memory(rsdp, sizeof(struct acpi_table_rsdp));

	if (table_entry_size == sizeof(u64)) {
		if (acpi_tb_check_xsdt(address) == AE_NULL_ENTRY) {
			/* XSDT has NULL entry, RSDT is used */
			address = rsdt_address;
			table_entry_size = sizeof(u32);
			ACPI_WARNING((AE_INFO, "BIOS XSDT has NULL entry, "
					"using RSDT"));
		}
	}
	/* Map the RSDT/XSDT table header to get the full table length */

	table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
	if (!table) {
		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	acpi_tb_print_table_header(address, table);

	/* Get the length of the full table, verify length and map entire table */

	length = table->length;
	acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));

	if (length < sizeof(struct acpi_table_header)) {
		ACPI_ERROR((AE_INFO, "Invalid length 0x%X in RSDT/XSDT",
			    length));
		return_ACPI_STATUS(AE_INVALID_TABLE_LENGTH);
	}

	table = acpi_os_map_memory(address, length);
	if (!table) {
		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	/* Validate the root table checksum */

	status = acpi_tb_verify_checksum(table, length);
	if (ACPI_FAILURE(status)) {
		acpi_os_unmap_memory(table, length);
		return_ACPI_STATUS(status);
	}

	/* Calculate the number of tables described in the root table */

	table_count = (u32)((table->length - sizeof(struct acpi_table_header)) /
			    table_entry_size);
	/*
	 * First two entries in the table array are reserved for the DSDT
	 * and FACS, which are not actually present in the RSDT/XSDT - they
	 * come from the FADT
	 */
	table_entry =
	    ACPI_CAST_PTR(u8, table) + sizeof(struct acpi_table_header);
	acpi_gbl_root_table_list.current_table_count = 2;

	/*
	 * Initialize the root table array from the RSDT/XSDT
	 */
	for (i = 0; i < table_count; i++) {
		if (acpi_gbl_root_table_list.current_table_count >=
		    acpi_gbl_root_table_list.max_table_count) {

			/* There is no more room in the root table array, attempt resize */

			status = acpi_tb_resize_root_table_list();
			if (ACPI_FAILURE(status)) {
				ACPI_WARNING((AE_INFO,
					      "Truncating %u table entries!",
					      (unsigned) (table_count -
					       (acpi_gbl_root_table_list.
							  current_table_count -
							  2))));
				break;
			}
		}

		/* Get the table physical address (32-bit for RSDT, 64-bit for XSDT) */

		acpi_gbl_root_table_list.tables[acpi_gbl_root_table_list.
						current_table_count].address =
		    acpi_tb_get_root_table_entry(table_entry, table_entry_size);

		table_entry += table_entry_size;
		acpi_gbl_root_table_list.current_table_count++;
	}

	/*
	 * It is not possible to map more than one entry in some environments,
	 * so unmap the root table here before mapping other tables
	 */
	acpi_os_unmap_memory(table, length);

	/*
	 * Complete the initialization of the root table array by examining
	 * the header of each table
	 */
	for (i = 2; i < acpi_gbl_root_table_list.current_table_count; i++) {
		acpi_tb_install_table(acpi_gbl_root_table_list.tables[i].
				      address, NULL, i);

		/* Special case for FADT - get the DSDT and FACS */

		if (ACPI_COMPARE_NAME
		    (&acpi_gbl_root_table_list.tables[i].signature,
		     ACPI_SIG_FADT)) {
			acpi_tb_parse_fadt(i);
		}
	}

	return_ACPI_STATUS(AE_OK);
}