drivers/acpi/tables/tbxfroot.c

   1 /******************************************************************************
   2  *
   3  * Module Name: tbxfroot - Find the root ACPI table (RSDT)
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2005, R. Byron Moore
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <linux/module.h>
  45
  46 #include <acpi/acpi.h>
  47 #include <acpi/actables.h>
  48
  49
  50 #define _COMPONENT          ACPI_TABLES
  51          ACPI_MODULE_NAME    ("tbxfroot")
  52
  53 /* Local prototypes */
  54
  55 static acpi_status
  56 acpi_tb_find_rsdp (
  57         struct acpi_table_desc          *table_info,
  58         u32                             flags);
  59
  60 static u8 *
  61 acpi_tb_scan_memory_for_rsdp (
  62         u8                              *start_address,
  63         u32                             length);
  64
  65
  66 /*******************************************************************************
  67  *
  68  * FUNCTION:    acpi_tb_find_table
  69  *
  70  * PARAMETERS:  Signature           - String with ACPI table signature
  71  *              oem_id              - String with the table OEM ID
  72  *              oem_table_id        - String with the OEM Table ID
  73  *              table_ptr           - Where the table pointer is returned
  74  *
  75  * RETURN:      Status
  76  *
  77  * DESCRIPTION: Find an ACPI table (in the RSDT/XSDT) that matches the
  78  *              Signature, OEM ID and OEM Table ID.
  79  *
  80  ******************************************************************************/
  81
  82 acpi_status
  83 acpi_tb_find_table (
  84         char                            *signature,
  85         char                            *oem_id,
  86         char                            *oem_table_id,
  87         struct acpi_table_header        **table_ptr)
  88 {
  89         acpi_status                     status;
  90         struct acpi_table_header        *table;
  91
  92
  93         ACPI_FUNCTION_TRACE ("tb_find_table");
  94
  95
  96         /* Validate string lengths */
  97
  98         if ((ACPI_STRLEN (signature)  > ACPI_NAME_SIZE) ||
  99                 (ACPI_STRLEN (oem_id)     > sizeof (table->oem_id)) ||
 100                 (ACPI_STRLEN (oem_table_id) > sizeof (table->oem_table_id))) {
 101                 return_ACPI_STATUS (AE_AML_STRING_LIMIT);
 102         }
 103
 104         if (!ACPI_STRNCMP (signature, DSDT_SIG, ACPI_NAME_SIZE)) {
 105                 /*
 106                  * The DSDT pointer is contained in the FADT, not the RSDT.
 107                  * This code should suffice, because the only code that would perform
 108                  * a "find" on the DSDT is the data_table_region() AML opcode -- in
 109                  * which case, the DSDT is guaranteed to be already loaded.
 110                  * If this becomes insufficient, the FADT will have to be found first.
 111                  */
 112                 if (!acpi_gbl_DSDT) {
 113                         return_ACPI_STATUS (AE_NO_ACPI_TABLES);
 114                 }
 115                 table = acpi_gbl_DSDT;
 116         }
 117         else {
 118                 /* Find the table */
 119
 120                 status = acpi_get_firmware_table (signature, 1,
 121                                  ACPI_LOGICAL_ADDRESSING, &table);
 122                 if (ACPI_FAILURE (status)) {
 123                         return_ACPI_STATUS (status);
 124                 }
 125         }
 126
 127         /* Check oem_id and oem_table_id */
 128
 129         if ((oem_id[0] && ACPI_STRNCMP (
 130                            oem_id, table->oem_id,
 131                            sizeof (table->oem_id))) ||
 132
 133                 (oem_table_id[0] && ACPI_STRNCMP (
 134                                    oem_table_id, table->oem_table_id,
 135                                    sizeof (table->oem_table_id)))) {
 136                 return_ACPI_STATUS (AE_AML_NAME_NOT_FOUND);
 137         }
 138
 139         ACPI_DEBUG_PRINT ((ACPI_DB_TABLES, "Found table [%4.4s]\n",
 140                 table->signature));
 141
 142         *table_ptr = table;
 143         return_ACPI_STATUS (AE_OK);
 144 }
 145
 146
 147 /*******************************************************************************
 148  *
 149  * FUNCTION:    acpi_get_firmware_table
 150  *
 151  * PARAMETERS:  Signature       - Any ACPI table signature
 152  *              Instance        - the non zero instance of the table, allows
 153  *                                support for multiple tables of the same type
 154  *              Flags           - Physical/Virtual support
 155  *              table_pointer   - Where a buffer containing the table is
 156  *                                returned
 157  *
 158  * RETURN:      Status
 159  *
 160  * DESCRIPTION: This function is called to get an ACPI table. A buffer is
 161  *              allocated for the table and returned in table_pointer.
 162  *              This table will be a complete table including the header.
 163  *
 164  ******************************************************************************/
 165
 166 acpi_status
 167 acpi_get_firmware_table (
 168         acpi_string                     signature,
 169         u32                             instance,
 170         u32                             flags,
 171         struct acpi_table_header        **table_pointer)
 172 {
 173         acpi_status                     status;
 174         struct acpi_pointer             address;
 175         struct acpi_table_header        *header = NULL;
 176         struct acpi_table_desc          *table_info = NULL;
 177         struct acpi_table_desc          *rsdt_info;
 178         u32                             table_count;
 179         u32                             i;
 180         u32                             j;
 181
 182
 183         ACPI_FUNCTION_TRACE ("acpi_get_firmware_table");
 184
 185
 186         /*
 187          * Ensure that at least the table manager is initialized.  We don't
 188          * require that the entire ACPI subsystem is up for this interface.
 189          * If we have a buffer, we must have a length too
 190          */
 191         if ((instance == 0)     ||
 192                 (!signature)        ||
 193                 (!table_pointer)) {
 194                 return_ACPI_STATUS (AE_BAD_PARAMETER);
 195         }
 196
 197         /* Ensure that we have a RSDP */
 198
 199         if (!acpi_gbl_RSDP) {
 200                 /* Get the RSDP */
 201
 202                 status = acpi_os_get_root_pointer (flags, &address);
 203                 if (ACPI_FAILURE (status)) {
 204                         ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "RSDP not found\n"));
 205                         return_ACPI_STATUS (AE_NO_ACPI_TABLES);
 206                 }
 207
 208                 /* Map and validate the RSDP */
 209
 210                 if ((flags & ACPI_MEMORY_MODE) == ACPI_LOGICAL_ADDRESSING) {
 211                         status = acpi_os_map_memory (address.pointer.physical,
 212                                          sizeof (struct rsdp_descriptor), (void *) &acpi_gbl_RSDP);
 213                         if (ACPI_FAILURE (status)) {
 214                                 return_ACPI_STATUS (status);
 215                         }
 216                 }
 217                 else {
 218                         acpi_gbl_RSDP = address.pointer.logical;
 219                 }
 220
 221                 /* The signature and checksum must both be correct */
 222
 223                 if (ACPI_STRNCMP ((char *) acpi_gbl_RSDP, RSDP_SIG,
 224                                 sizeof (RSDP_SIG)-1) != 0) {
 225                         /* Nope, BAD Signature */
 226
 227                         return_ACPI_STATUS (AE_BAD_SIGNATURE);
 228                 }
 229
 230                 if (acpi_tb_checksum (acpi_gbl_RSDP, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
 231                         /* Nope, BAD Checksum */
 232
 233                         return_ACPI_STATUS (AE_BAD_CHECKSUM);
 234                 }
 235         }
 236
 237         /* Get the RSDT address via the RSDP */
 238
 239         acpi_tb_get_rsdt_address (&address);
 240         ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
 241                 "RSDP located at %p, RSDT physical=%8.8X%8.8X \n",
 242                 acpi_gbl_RSDP,
 243                 ACPI_FORMAT_UINT64 (address.pointer.value)));
 244
 245         /* Insert processor_mode flags */
 246
 247         address.pointer_type |= flags;
 248
 249         /* Get and validate the RSDT */
 250
 251         rsdt_info = ACPI_MEM_CALLOCATE (sizeof (struct acpi_table_desc));
 252         if (!rsdt_info) {
 253                 return_ACPI_STATUS (AE_NO_MEMORY);
 254         }
 255
 256         status = acpi_tb_get_table (&address, rsdt_info);
 257         if (ACPI_FAILURE (status)) {
 258                 goto cleanup;
 259         }
 260
 261         status = acpi_tb_validate_rsdt (rsdt_info->pointer);
 262         if (ACPI_FAILURE (status)) {
 263                 goto cleanup;
 264         }
 265
 266         /* Allocate a scratch table header and table descriptor */
 267
 268         header = ACPI_MEM_ALLOCATE (sizeof (struct acpi_table_header));
 269         if (!header) {
 270                 status = AE_NO_MEMORY;
 271                 goto cleanup;
 272         }
 273
 274         table_info = ACPI_MEM_ALLOCATE (sizeof (struct acpi_table_desc));
 275         if (!table_info) {
 276                 status = AE_NO_MEMORY;
 277                 goto cleanup;
 278         }
 279
 280         /* Get the number of table pointers within the RSDT */
 281
 282         table_count = acpi_tb_get_table_count (acpi_gbl_RSDP, rsdt_info->pointer);
 283         address.pointer_type = acpi_gbl_table_flags | flags;
 284
 285         /*
 286          * Search the RSDT/XSDT for the correct instance of the
 287          * requested table
 288          */
 289         for (i = 0, j = 0; i < table_count; i++) {
 290                 /* Get the next table pointer, handle RSDT vs. XSDT */
 291
 292                 if (acpi_gbl_RSDP->revision < 2) {
 293                         address.pointer.value = (ACPI_CAST_PTR (
 294                                 RSDT_DESCRIPTOR, rsdt_info->pointer))->table_offset_entry[i];
 295                 }
 296                 else {
 297                         address.pointer.value = (ACPI_CAST_PTR (
 298                                 XSDT_DESCRIPTOR, rsdt_info->pointer))->table_offset_entry[i];
 299                 }
 300
 301                 /* Get the table header */
 302
 303                 status = acpi_tb_get_table_header (&address, header);
 304                 if (ACPI_FAILURE (status)) {
 305                         goto cleanup;
 306                 }
 307
 308                 /* Compare table signatures and table instance */
 309
 310                 if (!ACPI_STRNCMP (header->signature, signature, ACPI_NAME_SIZE)) {
 311                         /* An instance of the table was found */
 312
 313                         j++;
 314                         if (j >= instance) {
 315                                 /* Found the correct instance, get the entire table */
 316
 317                                 status = acpi_tb_get_table_body (&address, header, table_info);
 318                                 if (ACPI_FAILURE (status)) {
 319                                         goto cleanup;
 320                                 }
 321
 322                                 *table_pointer = table_info->pointer;
 323                                 goto cleanup;
 324                         }
 325                 }
 326         }
 327
 328         /* Did not find the table */
 329
 330         status = AE_NOT_EXIST;
 331
 332
 333 cleanup:
 334         acpi_os_unmap_memory (rsdt_info->pointer,
 335                 (acpi_size) rsdt_info->pointer->length);
 336         ACPI_MEM_FREE (rsdt_info);
 337
 338         if (header) {
 339                 ACPI_MEM_FREE (header);
 340         }
 341         if (table_info) {
 342                 ACPI_MEM_FREE (table_info);
 343         }
 344         return_ACPI_STATUS (status);
 345 }
 346 EXPORT_SYMBOL(acpi_get_firmware_table);
 347
 348
 349 /* TBD: Move to a new file */
 350
 351 #if ACPI_MACHINE_WIDTH != 16
 352
 353 /*******************************************************************************
 354  *
 355  * FUNCTION:    acpi_find_root_pointer
 356  *
 357  * PARAMETERS:  Flags                   - Logical/Physical addressing
 358  *              rsdp_address            - Where to place the RSDP address
 359  *
 360  * RETURN:      Status, Physical address of the RSDP
 361  *
 362  * DESCRIPTION: Find the RSDP
 363  *
 364  ******************************************************************************/
 365
 366 acpi_status
 367 acpi_find_root_pointer (
 368         u32                             flags,
 369         struct acpi_pointer             *rsdp_address)
 370 {
 371         struct acpi_table_desc          table_info;
 372         acpi_status                     status;
 373
 374
 375         ACPI_FUNCTION_TRACE ("acpi_find_root_pointer");
 376
 377
 378         /* Get the RSDP */
 379
 380         status = acpi_tb_find_rsdp (&table_info, flags);
 381         if (ACPI_FAILURE (status)) {
 382                 ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
 383                         "RSDP structure not found, %s Flags=%X\n",
 384                         acpi_format_exception (status), flags));
 385
 386                 return_ACPI_STATUS (AE_NO_ACPI_TABLES);
 387         }
 388
 389         rsdp_address->pointer_type = ACPI_PHYSICAL_POINTER;
 390         rsdp_address->pointer.physical = table_info.physical_address;
 391         return_ACPI_STATUS (AE_OK);
 392 }
 393
 394
 395 /*******************************************************************************
 396  *
 397  * FUNCTION:    acpi_tb_scan_memory_for_rsdp
 398  *
 399  * PARAMETERS:  start_address       - Starting pointer for search
 400  *              Length              - Maximum length to search
 401  *
 402  * RETURN:      Pointer to the RSDP if found, otherwise NULL.
 403  *
 404  * DESCRIPTION: Search a block of memory for the RSDP signature
 405  *
 406  ******************************************************************************/
 407
 408 static u8 *
 409 acpi_tb_scan_memory_for_rsdp (
 410         u8                              *start_address,
 411         u32                             length)
 412 {
 413         u8                              *mem_rover;
 414         u8                              *end_address;
 415         u8                              checksum;
 416
 417
 418         ACPI_FUNCTION_TRACE ("tb_scan_memory_for_rsdp");
 419
 420
 421         end_address = start_address + length;
 422
 423         /* Search from given start address for the requested length */
 424
 425         for (mem_rover = start_address; mem_rover < end_address;
 426                  mem_rover += ACPI_RSDP_SCAN_STEP) {
 427                 /* The signature and checksum must both be correct */
 428
 429                 if (ACPI_STRNCMP ((char *) mem_rover,
 430                                 RSDP_SIG, sizeof (RSDP_SIG) - 1) != 0) {
 431                         /* No signature match, keep looking */
 432
 433                         continue;
 434                 }
 435
 436                 /* Signature matches, check the appropriate checksum */
 437
 438                 if ((ACPI_CAST_PTR (struct rsdp_descriptor, mem_rover))->revision < 2) {
 439                         /* ACPI version 1.0 */
 440
 441                         checksum = acpi_tb_checksum (mem_rover, ACPI_RSDP_CHECKSUM_LENGTH);
 442                 }
 443                 else {
 444                         /* Post ACPI 1.0, use extended_checksum */
 445
 446                         checksum = acpi_tb_checksum (mem_rover, ACPI_RSDP_XCHECKSUM_LENGTH);
 447                 }
 448
 449                 if (checksum == 0) {
 450                         /* Checksum valid, we have found a valid RSDP */
 451
 452                         ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
 453                                 "RSDP located at physical address %p\n", mem_rover));
 454                         return_PTR (mem_rover);
 455                 }
 456
 457                 ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
 458                         "Found an RSDP at physical address %p, but it has a bad checksum\n",
 459                         mem_rover));
 460         }
 461
 462         /* Searched entire block, no RSDP was found */
 463
 464         ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
 465                 "Searched entire block, no valid RSDP was found.\n"));
 466         return_PTR (NULL);
 467 }
 468
 469
 470 /*******************************************************************************
 471  *
 472  * FUNCTION:    acpi_tb_find_rsdp
 473  *
 474  * PARAMETERS:  table_info              - Where the table info is returned
 475  *              Flags                   - Current memory mode (logical vs.
 476  *                                        physical addressing)
 477  *
 478  * RETURN:      Status, RSDP physical address
 479  *
 480  * DESCRIPTION: search lower 1_mbyte of memory for the root system descriptor
 481  *              pointer structure.  If it is found, set *RSDP to point to it.
 482  *
 483  *              NOTE1: The RSDp must be either in the first 1_k of the Extended
 484  *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
 485  *              Only a 32-bit physical address is necessary.
 486  *
 487  *              NOTE2: This function is always available, regardless of the
 488  *              initialization state of the rest of ACPI.
 489  *
 490  ******************************************************************************/
 491
 492 static acpi_status
 493 acpi_tb_find_rsdp (
 494         struct acpi_table_desc          *table_info,
 495         u32                             flags)
 496 {
 497         u8                              *table_ptr;
 498         u8                              *mem_rover;
 499         u32                             physical_address;
 500         acpi_status                     status;
 501
 502
 503         ACPI_FUNCTION_TRACE ("tb_find_rsdp");
 504
 505
 506         /*
 507          * Scan supports either logical addressing or physical addressing
 508          */
 509         if ((flags & ACPI_MEMORY_MODE) == ACPI_LOGICAL_ADDRESSING) {
 510                 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
 511
 512                 status = acpi_os_map_memory (
 513                                  (acpi_physical_address) ACPI_EBDA_PTR_LOCATION,
 514                                  ACPI_EBDA_PTR_LENGTH, (void *) &table_ptr);
 515                 if (ACPI_FAILURE (status)) {
 516                         ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
 517                                 "Could not map memory at %8.8X for length %X\n",
 518                                 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
 519
 520                         return_ACPI_STATUS (status);
 521                 }
 522
 523                 ACPI_MOVE_16_TO_32 (&physical_address, table_ptr);
 524
 525                 /* Convert segment part to physical address */
 526
 527                 physical_address <<= 4;
 528                 acpi_os_unmap_memory (table_ptr, ACPI_EBDA_PTR_LENGTH);
 529
 530                 /* EBDA present? */
 531
 532                 if (physical_address > 0x400) {
 533                         /*
 534                          * 1b) Search EBDA paragraphs (EBDa is required to be a
 535                          *     minimum of 1_k length)
 536                          */
 537                         status = acpi_os_map_memory (
 538                                          (acpi_physical_address) physical_address,
 539                                          ACPI_EBDA_WINDOW_SIZE, (void *) &table_ptr);
 540                         if (ACPI_FAILURE (status)) {
 541                                 ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
 542                                         "Could not map memory at %8.8X for length %X\n",
 543                                         physical_address, ACPI_EBDA_WINDOW_SIZE));
 544
 545                                 return_ACPI_STATUS (status);
 546                         }
 547
 548                         mem_rover = acpi_tb_scan_memory_for_rsdp (table_ptr,
 549                                           ACPI_EBDA_WINDOW_SIZE);
 550                         acpi_os_unmap_memory (table_ptr, ACPI_EBDA_WINDOW_SIZE);
 551
 552                         if (mem_rover) {
 553                                 /* Found it, return the physical address */
 554
 555                                 physical_address += ACPI_PTR_DIFF (mem_rover, table_ptr);
 556
 557                                 table_info->physical_address =
 558                                         (acpi_physical_address) physical_address;
 559                                 return_ACPI_STATUS (AE_OK);
 560                         }
 561                 }
 562
 563                 /*
 564                  * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
 565                  */
 566                 status = acpi_os_map_memory (
 567                                  (acpi_physical_address) ACPI_HI_RSDP_WINDOW_BASE,
 568                                  ACPI_HI_RSDP_WINDOW_SIZE, (void *) &table_ptr);
 569
 570                 if (ACPI_FAILURE (status)) {
 571                         ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
 572                                 "Could not map memory at %8.8X for length %X\n",
 573                                 ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE));
 574
 575                         return_ACPI_STATUS (status);
 576                 }
 577
 578                 mem_rover = acpi_tb_scan_memory_for_rsdp (table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 579                 acpi_os_unmap_memory (table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 580
 581                 if (mem_rover) {
 582                         /* Found it, return the physical address */
 583
 584                         physical_address =
 585                                 ACPI_HI_RSDP_WINDOW_BASE + ACPI_PTR_DIFF (mem_rover, table_ptr);
 586
 587                         table_info->physical_address =
 588                                 (acpi_physical_address) physical_address;
 589                         return_ACPI_STATUS (AE_OK);
 590                 }
 591         }
 592
 593         /*
 594          * Physical addressing
 595          */
 596         else {
 597                 /* 1a) Get the location of the EBDA */
 598
 599                 ACPI_MOVE_16_TO_32 (&physical_address, ACPI_EBDA_PTR_LOCATION);
 600                 physical_address <<= 4;     /* Convert segment to physical address */
 601
 602                 /* EBDA present? */
 603
 604                 if (physical_address > 0x400) {
 605                         /*
 606                          * 1b) Search EBDA paragraphs (EBDa is required to be a minimum of
 607                          *     1_k length)
 608                          */
 609                         mem_rover = acpi_tb_scan_memory_for_rsdp (
 610                                           ACPI_PHYSADDR_TO_PTR (physical_address),
 611                                           ACPI_EBDA_WINDOW_SIZE);
 612                         if (mem_rover) {
 613                                 /* Found it, return the physical address */
 614
 615                                 table_info->physical_address = ACPI_TO_INTEGER (mem_rover);
 616                                 return_ACPI_STATUS (AE_OK);
 617                         }
 618                 }
 619
 620                 /* 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh */
 621
 622                 mem_rover = acpi_tb_scan_memory_for_rsdp (
 623                                   ACPI_PHYSADDR_TO_PTR (ACPI_HI_RSDP_WINDOW_BASE),
 624                                   ACPI_HI_RSDP_WINDOW_SIZE);
 625                 if (mem_rover) {
 626                         /* Found it, return the physical address */
 627
 628                         table_info->physical_address = ACPI_TO_INTEGER (mem_rover);
 629                         return_ACPI_STATUS (AE_OK);
 630                 }
 631         }
 632
 633         /* RSDP signature was not found */
 634
 635         return_ACPI_STATUS (AE_NOT_FOUND);
 636 }
 637
 638 #endif
 639