arch/x86/kernel/e820_32.c

   1 #include <linux/kernel.h>
   2 #include <linux/types.h>
   3 #include <linux/init.h>
   4 #include <linux/bootmem.h>
   5 #include <linux/ioport.h>
   6 #include <linux/string.h>
   7 #include <linux/kexec.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/pfn.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/suspend.h>
  13
  14 #include <asm/pgtable.h>
  15 #include <asm/page.h>
  16 #include <asm/e820.h>
  17 #include <asm/setup.h>
  18
  19 struct e820map e820;
  20 struct change_member {
  21         struct e820entry *pbios; /* pointer to original bios entry */
  22         unsigned long long addr; /* address for this change point */
  23 };
  24 static struct change_member change_point_list[2*E820MAX] __initdata;
  25 static struct change_member *change_point[2*E820MAX] __initdata;
  26 static struct e820entry *overlap_list[E820MAX] __initdata;
  27 static struct e820entry new_bios[E820MAX] __initdata;
  28 /* For PCI or other memory-mapped resources */
  29 unsigned long pci_mem_start = 0x10000000;
  30 #ifdef CONFIG_PCI
  31 EXPORT_SYMBOL(pci_mem_start);
  32 #endif
  33 extern int user_defined_memmap;
  34
  35 static struct resource system_rom_resource = {
  36         .name   = "System ROM",
  37         .start  = 0xf0000,
  38         .end    = 0xfffff,
  39         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  40 };
  41
  42 static struct resource extension_rom_resource = {
  43         .name   = "Extension ROM",
  44         .start  = 0xe0000,
  45         .end    = 0xeffff,
  46         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  47 };
  48
  49 static struct resource adapter_rom_resources[] = { {
  50         .name   = "Adapter ROM",
  51         .start  = 0xc8000,
  52         .end    = 0,
  53         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  54 }, {
  55         .name   = "Adapter ROM",
  56         .start  = 0,
  57         .end    = 0,
  58         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  59 }, {
  60         .name   = "Adapter ROM",
  61         .start  = 0,
  62         .end    = 0,
  63         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  64 }, {
  65         .name   = "Adapter ROM",
  66         .start  = 0,
  67         .end    = 0,
  68         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  69 }, {
  70         .name   = "Adapter ROM",
  71         .start  = 0,
  72         .end    = 0,
  73         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  74 }, {
  75         .name   = "Adapter ROM",
  76         .start  = 0,
  77         .end    = 0,
  78         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  79 } };
  80
  81 static struct resource video_rom_resource = {
  82         .name   = "Video ROM",
  83         .start  = 0xc0000,
  84         .end    = 0xc7fff,
  85         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  86 };
  87
  88 #define ROMSIGNATURE 0xaa55
  89
  90 static int __init romsignature(const unsigned char *rom)
  91 {
  92         const unsigned short * const ptr = (const unsigned short *)rom;
  93         unsigned short sig;
  94
  95         return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
  96 }
  97
  98 static int __init romchecksum(const unsigned char *rom, unsigned long length)
  99 {
 100         unsigned char sum, c;
 101
 102         for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
 103                 sum += c;
 104         return !length && !sum;
 105 }
 106
 107 static void __init probe_roms(void)
 108 {
 109         const unsigned char *rom;
 110         unsigned long start, length, upper;
 111         unsigned char c;
 112         int i;
 113
 114         /* video rom */
 115         upper = adapter_rom_resources[0].start;
 116         for (start = video_rom_resource.start; start < upper; start += 2048) {
 117                 rom = isa_bus_to_virt(start);
 118                 if (!romsignature(rom))
 119                         continue;
 120
 121                 video_rom_resource.start = start;
 122
 123                 if (probe_kernel_address(rom + 2, c) != 0)
 124                         continue;
 125
 126                 /* 0 < length <= 0x7f * 512, historically */
 127                 length = c * 512;
 128
 129                 /* if checksum okay, trust length byte */
 130                 if (length && romchecksum(rom, length))
 131                         video_rom_resource.end = start + length - 1;
 132
 133                 request_resource(&iomem_resource, &video_rom_resource);
 134                 break;
 135         }
 136
 137         start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
 138         if (start < upper)
 139                 start = upper;
 140
 141         /* system rom */
 142         request_resource(&iomem_resource, &system_rom_resource);
 143         upper = system_rom_resource.start;
 144
 145         /* check for extension rom (ignore length byte!) */
 146         rom = isa_bus_to_virt(extension_rom_resource.start);
 147         if (romsignature(rom)) {
 148                 length = extension_rom_resource.end - extension_rom_resource.start + 1;
 149                 if (romchecksum(rom, length)) {
 150                         request_resource(&iomem_resource, &extension_rom_resource);
 151                         upper = extension_rom_resource.start;
 152                 }
 153         }
 154
 155         /* check for adapter roms on 2k boundaries */
 156         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
 157                 rom = isa_bus_to_virt(start);
 158                 if (!romsignature(rom))
 159                         continue;
 160
 161                 if (probe_kernel_address(rom + 2, c) != 0)
 162                         continue;
 163
 164                 /* 0 < length <= 0x7f * 512, historically */
 165                 length = c * 512;
 166
 167                 /* but accept any length that fits if checksum okay */
 168                 if (!length || start + length > upper || !romchecksum(rom, length))
 169                         continue;
 170
 171                 adapter_rom_resources[i].start = start;
 172                 adapter_rom_resources[i].end = start + length - 1;
 173                 request_resource(&iomem_resource, &adapter_rom_resources[i]);
 174
 175                 start = adapter_rom_resources[i++].end & ~2047UL;
 176         }
 177 }
 178
 179 /*
 180  * Request address space for all standard RAM and ROM resources
 181  * and also for regions reported as reserved by the e820.
 182  */
 183 void __init init_iomem_resources(struct resource *code_resource,
 184                 struct resource *data_resource,
 185                 struct resource *bss_resource)
 186 {
 187         int i;
 188
 189         probe_roms();
 190         for (i = 0; i < e820.nr_map; i++) {
 191                 struct resource *res;
 192 #ifndef CONFIG_RESOURCES_64BIT
 193                 if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
 194                         continue;
 195 #endif
 196                 res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
 197                 switch (e820.map[i].type) {
 198                 case E820_RAM:  res->name = "System RAM"; break;
 199                 case E820_ACPI: res->name = "ACPI Tables"; break;
 200                 case E820_NVS:  res->name = "ACPI Non-volatile Storage"; break;
 201                 default:        res->name = "reserved";
 202                 }
 203                 res->start = e820.map[i].addr;
 204                 res->end = res->start + e820.map[i].size - 1;
 205                 res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 206                 if (request_resource(&iomem_resource, res)) {
 207                         kfree(res);
 208                         continue;
 209                 }
 210                 if (e820.map[i].type == E820_RAM) {
 211                         /*
 212                          *  We don't know which RAM region contains kernel data,
 213                          *  so we try it repeatedly and let the resource manager
 214                          *  test it.
 215                          */
 216                         request_resource(res, code_resource);
 217                         request_resource(res, data_resource);
 218                         request_resource(res, bss_resource);
 219 #ifdef CONFIG_KEXEC
 220                         if (crashk_res.start != crashk_res.end)
 221                                 request_resource(res, &crashk_res);
 222 #endif
 223                 }
 224         }
 225 }
 226
 227 #if defined(CONFIG_PM) && defined(CONFIG_HIBERNATION)
 228 /**
 229  * e820_mark_nosave_regions - Find the ranges of physical addresses that do not
 230  * correspond to e820 RAM areas and mark the corresponding pages as nosave for
 231  * hibernation.
 232  *
 233  * This function requires the e820 map to be sorted and without any
 234  * overlapping entries and assumes the first e820 area to be RAM.
 235  */
 236 void __init e820_mark_nosave_regions(void)
 237 {
 238         int i;
 239         unsigned long pfn;
 240
 241         pfn = PFN_DOWN(e820.map[0].addr + e820.map[0].size);
 242         for (i = 1; i < e820.nr_map; i++) {
 243                 struct e820entry *ei = &e820.map[i];
 244
 245                 if (pfn < PFN_UP(ei->addr))
 246                         register_nosave_region(pfn, PFN_UP(ei->addr));
 247
 248                 pfn = PFN_DOWN(ei->addr + ei->size);
 249                 if (ei->type != E820_RAM)
 250                         register_nosave_region(PFN_UP(ei->addr), pfn);
 251
 252                 if (pfn >= max_low_pfn)
 253                         break;
 254         }
 255 }
 256 #endif
 257
 258 void __init add_memory_region(unsigned long long start,
 259                               unsigned long long size, int type)
 260 {
 261         int x;
 262
 263         x = e820.nr_map;
 264
 265         if (x == E820MAX) {
 266                 printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
 267                 return;
 268         }
 269
 270         e820.map[x].addr = start;
 271         e820.map[x].size = size;
 272         e820.map[x].type = type;
 273         e820.nr_map++;
 274 } /* add_memory_region */
 275
 276 /*
 277  * Sanitize the BIOS e820 map.
 278  *
 279  * Some e820 responses include overlapping entries.  The following
 280  * replaces the original e820 map with a new one, removing overlaps.
 281  *
 282  */
 283 int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
 284 {
 285         struct change_member *change_tmp;
 286         unsigned long current_type, last_type;
 287         unsigned long long last_addr;
 288         int chgidx, still_changing;
 289         int overlap_entries;
 290         int new_bios_entry;
 291         int old_nr, new_nr, chg_nr;
 292         int i;
 293
 294         /*
 295                 Visually we're performing the following (1,2,3,4 = memory types)...
 296
 297                 Sample memory map (w/overlaps):
 298                    ____22__________________
 299                    ______________________4_
 300                    ____1111________________
 301                    _44_____________________
 302                    11111111________________
 303                    ____________________33__
 304                    ___________44___________
 305                    __________33333_________
 306                    ______________22________
 307                    ___________________2222_
 308                    _________111111111______
 309                    _____________________11_
 310                    _________________4______
 311
 312                 Sanitized equivalent (no overlap):
 313                    1_______________________
 314                    _44_____________________
 315                    ___1____________________
 316                    ____22__________________
 317                    ______11________________
 318                    _________1______________
 319                    __________3_____________
 320                    ___________44___________
 321                    _____________33_________
 322                    _______________2________
 323                    ________________1_______
 324                    _________________4______
 325                    ___________________2____
 326                    ____________________33__
 327                    ______________________4_
 328         */
 329         /* if there's only one memory region, don't bother */
 330         if (*pnr_map < 2) {
 331                 return -1;
 332         }
 333
 334         old_nr = *pnr_map;
 335
 336         /* bail out if we find any unreasonable addresses in bios map */
 337         for (i=0; i<old_nr; i++)
 338                 if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr) {
 339                         return -1;
 340                 }
 341
 342         /* create pointers for initial change-point information (for sorting) */
 343         for (i=0; i < 2*old_nr; i++)
 344                 change_point[i] = &change_point_list[i];
 345
 346         /* record all known change-points (starting and ending addresses),
 347            omitting those that are for empty memory regions */
 348         chgidx = 0;
 349         for (i=0; i < old_nr; i++)      {
 350                 if (biosmap[i].size != 0) {
 351                         change_point[chgidx]->addr = biosmap[i].addr;
 352                         change_point[chgidx++]->pbios = &biosmap[i];
 353                         change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
 354                         change_point[chgidx++]->pbios = &biosmap[i];
 355                 }
 356         }
 357         chg_nr = chgidx;        /* true number of change-points */
 358
 359         /* sort change-point list by memory addresses (low -> high) */
 360         still_changing = 1;
 361         while (still_changing)  {
 362                 still_changing = 0;
 363                 for (i=1; i < chg_nr; i++)  {
 364                         /* if <current_addr> > <last_addr>, swap */
 365                         /* or, if current=<start_addr> & last=<end_addr>, swap */
 366                         if ((change_point[i]->addr < change_point[i-1]->addr) ||
 367                                 ((change_point[i]->addr == change_point[i-1]->addr) &&
 368                                  (change_point[i]->addr == change_point[i]->pbios->addr) &&
 369                                  (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
 370                            )
 371                         {
 372                                 change_tmp = change_point[i];
 373                                 change_point[i] = change_point[i-1];
 374                                 change_point[i-1] = change_tmp;
 375                                 still_changing=1;
 376                         }
 377                 }
 378         }
 379
 380         /* create a new bios memory map, removing overlaps */
 381         overlap_entries=0;       /* number of entries in the overlap table */
 382         new_bios_entry=0;        /* index for creating new bios map entries */
 383         last_type = 0;           /* start with undefined memory type */
 384         last_addr = 0;           /* start with 0 as last starting address */
 385         /* loop through change-points, determining affect on the new bios map */
 386         for (chgidx=0; chgidx < chg_nr; chgidx++)
 387         {
 388                 /* keep track of all overlapping bios entries */
 389                 if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
 390                 {
 391                         /* add map entry to overlap list (> 1 entry implies an overlap) */
 392                         overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
 393                 }
 394                 else
 395                 {
 396                         /* remove entry from list (order independent, so swap with last) */
 397                         for (i=0; i<overlap_entries; i++)
 398                         {
 399                                 if (overlap_list[i] == change_point[chgidx]->pbios)
 400                                         overlap_list[i] = overlap_list[overlap_entries-1];
 401                         }
 402                         overlap_entries--;
 403                 }
 404                 /* if there are overlapping entries, decide which "type" to use */
 405                 /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
 406                 current_type = 0;
 407                 for (i=0; i<overlap_entries; i++)
 408                         if (overlap_list[i]->type > current_type)
 409                                 current_type = overlap_list[i]->type;
 410                 /* continue building up new bios map based on this information */
 411                 if (current_type != last_type)  {
 412                         if (last_type != 0)      {
 413                                 new_bios[new_bios_entry].size =
 414                                         change_point[chgidx]->addr - last_addr;
 415                                 /* move forward only if the new size was non-zero */
 416                                 if (new_bios[new_bios_entry].size != 0)
 417                                         if (++new_bios_entry >= E820MAX)
 418                                                 break;  /* no more space left for new bios entries */
 419                         }
 420                         if (current_type != 0)  {
 421                                 new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
 422                                 new_bios[new_bios_entry].type = current_type;
 423                                 last_addr=change_point[chgidx]->addr;
 424                         }
 425                         last_type = current_type;
 426                 }
 427         }
 428         new_nr = new_bios_entry;   /* retain count for new bios entries */
 429
 430         /* copy new bios mapping into original location */
 431         memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
 432         *pnr_map = new_nr;
 433
 434         return 0;
 435 }
 436
 437 /*
 438  * Copy the BIOS e820 map into a safe place.
 439  *
 440  * Sanity-check it while we're at it..
 441  *
 442  * If we're lucky and live on a modern system, the setup code
 443  * will have given us a memory map that we can use to properly
 444  * set up memory.  If we aren't, we'll fake a memory map.
 445  *
 446  * We check to see that the memory map contains at least 2 elements
 447  * before we'll use it, because the detection code in setup.S may
 448  * not be perfect and most every PC known to man has two memory
 449  * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
 450  * thinkpad 560x, for example, does not cooperate with the memory
 451  * detection code.)
 452  */
 453 int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
 454 {
 455         /* Only one memory region (or negative)? Ignore it */
 456         if (nr_map < 2)
 457                 return -1;
 458
 459         do {
 460                 unsigned long long start = biosmap->addr;
 461                 unsigned long long size = biosmap->size;
 462                 unsigned long long end = start + size;
 463                 unsigned long type = biosmap->type;
 464
 465                 /* Overflow in 64 bits? Ignore the memory map. */
 466                 if (start > end)
 467                         return -1;
 468
 469                 /*
 470                  * Some BIOSes claim RAM in the 640k - 1M region.
 471                  * Not right. Fix it up.
 472                  */
 473                 if (type == E820_RAM) {
 474                         if (start < 0x100000ULL && end > 0xA0000ULL) {
 475                                 if (start < 0xA0000ULL)
 476                                         add_memory_region(start, 0xA0000ULL-start, type);
 477                                 if (end <= 0x100000ULL)
 478                                         continue;
 479                                 start = 0x100000ULL;
 480                                 size = end - start;
 481                         }
 482                 }
 483                 add_memory_region(start, size, type);
 484         } while (biosmap++,--nr_map);
 485         return 0;
 486 }
 487
 488 /*
 489  * Find the highest page frame number we have available
 490  */
 491 void __init find_max_pfn(void)
 492 {
 493         int i;
 494
 495         max_pfn = 0;
 496
 497         for (i = 0; i < e820.nr_map; i++) {
 498                 unsigned long start, end;
 499                 /* RAM? */
 500                 if (e820.map[i].type != E820_RAM)
 501                         continue;
 502                 start = PFN_UP(e820.map[i].addr);
 503                 end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
 504                 if (start >= end)
 505                         continue;
 506                 if (end > max_pfn)
 507                         max_pfn = end;
 508                 memory_present(0, start, end);
 509         }
 510 }
 511
 512 /*
 513  * Register fully available low RAM pages with the bootmem allocator.
 514  */
 515 void __init register_bootmem_low_pages(unsigned long max_low_pfn)
 516 {
 517         int i;
 518
 519         for (i = 0; i < e820.nr_map; i++) {
 520                 unsigned long curr_pfn, last_pfn, size;
 521                 /*
 522                  * Reserve usable low memory
 523                  */
 524                 if (e820.map[i].type != E820_RAM)
 525                         continue;
 526                 /*
 527                  * We are rounding up the start address of usable memory:
 528                  */
 529                 curr_pfn = PFN_UP(e820.map[i].addr);
 530                 if (curr_pfn >= max_low_pfn)
 531                         continue;
 532                 /*
 533                  * ... and at the end of the usable range downwards:
 534                  */
 535                 last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
 536
 537                 if (last_pfn > max_low_pfn)
 538                         last_pfn = max_low_pfn;
 539
 540                 /*
 541                  * .. finally, did all the rounding and playing
 542                  * around just make the area go away?
 543                  */
 544                 if (last_pfn <= curr_pfn)
 545                         continue;
 546
 547                 size = last_pfn - curr_pfn;
 548                 free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
 549         }
 550 }
 551
 552 void __init e820_register_memory(void)
 553 {
 554         unsigned long gapstart, gapsize, round;
 555         unsigned long long last;
 556         int i;
 557
 558         /*
 559          * Search for the biggest gap in the low 32 bits of the e820
 560          * memory space.
 561          */
 562         last = 0x100000000ull;
 563         gapstart = 0x10000000;
 564         gapsize = 0x400000;
 565         i = e820.nr_map;
 566         while (--i >= 0) {
 567                 unsigned long long start = e820.map[i].addr;
 568                 unsigned long long end = start + e820.map[i].size;
 569
 570                 /*
 571                  * Since "last" is at most 4GB, we know we'll
 572                  * fit in 32 bits if this condition is true
 573                  */
 574                 if (last > end) {
 575                         unsigned long gap = last - end;
 576
 577                         if (gap > gapsize) {
 578                                 gapsize = gap;
 579                                 gapstart = end;
 580                         }
 581                 }
 582                 if (start < last)
 583                         last = start;
 584         }
 585
 586         /*
 587          * See how much we want to round up: start off with
 588          * rounding to the next 1MB area.
 589          */
 590         round = 0x100000;
 591         while ((gapsize >> 4) > round)
 592                 round += round;
 593         /* Fun with two's complement */
 594         pci_mem_start = (gapstart + round) & -round;
 595
 596         printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
 597                 pci_mem_start, gapstart, gapsize);
 598 }
 599
 600 void __init print_memory_map(char *who)
 601 {
 602         int i;
 603
 604         for (i = 0; i < e820.nr_map; i++) {
 605                 printk(" %s: %016Lx - %016Lx ", who,
 606                         e820.map[i].addr,
 607                         e820.map[i].addr + e820.map[i].size);
 608                 switch (e820.map[i].type) {
 609                 case E820_RAM:  printk("(usable)\n");
 610                                 break;
 611                 case E820_RESERVED:
 612                                 printk("(reserved)\n");
 613                                 break;
 614                 case E820_ACPI:
 615                                 printk("(ACPI data)\n");
 616                                 break;
 617                 case E820_NVS:
 618                                 printk("(ACPI NVS)\n");
 619                                 break;
 620                 default:        printk("type %u\n", e820.map[i].type);
 621                                 break;
 622                 }
 623         }
 624 }
 625
 626 void __init limit_regions(unsigned long long size)
 627 {
 628         unsigned long long current_addr;
 629         int i;
 630
 631         print_memory_map("limit_regions start");
 632         for (i = 0; i < e820.nr_map; i++) {
 633                 current_addr = e820.map[i].addr + e820.map[i].size;
 634                 if (current_addr < size)
 635                         continue;
 636
 637                 if (e820.map[i].type != E820_RAM)
 638                         continue;
 639
 640                 if (e820.map[i].addr >= size) {
 641                         /*
 642                          * This region starts past the end of the
 643                          * requested size, skip it completely.
 644                          */
 645                         e820.nr_map = i;
 646                 } else {
 647                         e820.nr_map = i + 1;
 648                         e820.map[i].size -= current_addr - size;
 649                 }
 650                 print_memory_map("limit_regions endfor");
 651                 return;
 652         }
 653         print_memory_map("limit_regions endfunc");
 654 }
 655
 656 /*
 657  * This function checks if any part of the range <start,end> is mapped
 658  * with type.
 659  */
 660 int
 661 e820_any_mapped(u64 start, u64 end, unsigned type)
 662 {
 663         int i;
 664         for (i = 0; i < e820.nr_map; i++) {
 665                 const struct e820entry *ei = &e820.map[i];
 666                 if (type && ei->type != type)
 667                         continue;
 668                 if (ei->addr >= end || ei->addr + ei->size <= start)
 669                         continue;
 670                 return 1;
 671         }
 672         return 0;
 673 }
 674 EXPORT_SYMBOL_GPL(e820_any_mapped);
 675
 676  /*
 677   * This function checks if the entire range <start,end> is mapped with type.
 678   *
 679   * Note: this function only works correct if the e820 table is sorted and
 680   * not-overlapping, which is the case
 681   */
 682 int __init
 683 e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
 684 {
 685         u64 start = s;
 686         u64 end = e;
 687         int i;
 688         for (i = 0; i < e820.nr_map; i++) {
 689                 struct e820entry *ei = &e820.map[i];
 690                 if (type && ei->type != type)
 691                         continue;
 692                 /* is the region (part) in overlap with the current region ?*/
 693                 if (ei->addr >= end || ei->addr + ei->size <= start)
 694                         continue;
 695                 /* if the region is at the beginning of <start,end> we move
 696                  * start to the end of the region since it's ok until there
 697                  */
 698                 if (ei->addr <= start)
 699                         start = ei->addr + ei->size;
 700                 /* if start is now at or beyond end, we're done, full
 701                  * coverage */
 702                 if (start >= end)
 703                         return 1; /* we're done */
 704         }
 705         return 0;
 706 }
 707
 708 static int __init parse_memmap(char *arg)
 709 {
 710         if (!arg)
 711                 return -EINVAL;
 712
 713         if (strcmp(arg, "exactmap") == 0) {
 714 #ifdef CONFIG_CRASH_DUMP
 715                 /* If we are doing a crash dump, we
 716                  * still need to know the real mem
 717                  * size before original memory map is
 718                  * reset.
 719                  */
 720                 find_max_pfn();
 721                 saved_max_pfn = max_pfn;
 722 #endif
 723                 e820.nr_map = 0;
 724                 user_defined_memmap = 1;
 725         } else {
 726                 /* If the user specifies memory size, we
 727                  * limit the BIOS-provided memory map to
 728                  * that size. exactmap can be used to specify
 729                  * the exact map. mem=number can be used to
 730                  * trim the existing memory map.
 731                  */
 732                 unsigned long long start_at, mem_size;
 733
 734                 mem_size = memparse(arg, &arg);
 735                 if (*arg == '@') {
 736                         start_at = memparse(arg+1, &arg);
 737                         add_memory_region(start_at, mem_size, E820_RAM);
 738                 } else if (*arg == '#') {
 739                         start_at = memparse(arg+1, &arg);
 740                         add_memory_region(start_at, mem_size, E820_ACPI);
 741                 } else if (*arg == '$') {
 742                         start_at = memparse(arg+1, &arg);
 743                         add_memory_region(start_at, mem_size, E820_RESERVED);
 744                 } else {
 745                         limit_regions(mem_size);
 746                         user_defined_memmap = 1;
 747                 }
 748         }
 749         return 0;
 750 }
 751 early_param("memmap", parse_memmap);
 752 void __init update_e820(void)
 753 {
 754         u8 nr_map;
 755
 756         nr_map = e820.nr_map;
 757         if (sanitize_e820_map(e820.map, &nr_map))
 758                 return;
 759         e820.nr_map = nr_map;
 760         printk(KERN_INFO "modified physical RAM map:\n");
 761         print_memory_map("modified");
 762 }