git.oblomov.eu Git - linux-2.6/blob - arch/i386/kernel/e820.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/efi.h>
  11 #include <linux/pfn.h>
  12 #include <linux/uaccess.h>
  13
  14 #include <asm/pgtable.h>
  15 #include <asm/page.h>
  16 #include <asm/e820.h>
  17 #include <asm/setup.h>
  18
  19 #ifdef CONFIG_EFI
  20 int efi_enabled = 0;
  21 EXPORT_SYMBOL(efi_enabled);
  22 #endif
  23
  24 struct e820map e820;
  25 struct change_member {
  26         struct e820entry *pbios; /* pointer to original bios entry */
  27         unsigned long long addr; /* address for this change point */
  28 };
  29 static struct change_member change_point_list[2*E820MAX] __initdata;
  30 static struct change_member *change_point[2*E820MAX] __initdata;
  31 static struct e820entry *overlap_list[E820MAX] __initdata;
  32 static struct e820entry new_bios[E820MAX] __initdata;
  33 /* For PCI or other memory-mapped resources */
  34 unsigned long pci_mem_start = 0x10000000;
  35 #ifdef CONFIG_PCI
  36 EXPORT_SYMBOL(pci_mem_start);
  37 #endif
  38 extern int user_defined_memmap;
  39 struct resource data_resource = {
  40         .name   = "Kernel data",
  41         .start  = 0,
  42         .end    = 0,
  43         .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
  44 };
  45
  46 struct resource code_resource = {
  47         .name   = "Kernel code",
  48         .start  = 0,
  49         .end    = 0,
  50         .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
  51 };
  52
  53 static struct resource system_rom_resource = {
  54         .name   = "System ROM",
  55         .start  = 0xf0000,
  56         .end    = 0xfffff,
  57         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  58 };
  59
  60 static struct resource extension_rom_resource = {
  61         .name   = "Extension ROM",
  62         .start  = 0xe0000,
  63         .end    = 0xeffff,
  64         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  65 };
  66
  67 static struct resource adapter_rom_resources[] = { {
  68         .name   = "Adapter ROM",
  69         .start  = 0xc8000,
  70         .end    = 0,
  71         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  72 }, {
  73         .name   = "Adapter ROM",
  74         .start  = 0,
  75         .end    = 0,
  76         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  77 }, {
  78         .name   = "Adapter ROM",
  79         .start  = 0,
  80         .end    = 0,
  81         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  82 }, {
  83         .name   = "Adapter ROM",
  84         .start  = 0,
  85         .end    = 0,
  86         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  87 }, {
  88         .name   = "Adapter ROM",
  89         .start  = 0,
  90         .end    = 0,
  91         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  92 }, {
  93         .name   = "Adapter ROM",
  94         .start  = 0,
  95         .end    = 0,
  96         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  97 } };
  98
  99 static struct resource video_rom_resource = {
 100         .name   = "Video ROM",
 101         .start  = 0xc0000,
 102         .end    = 0xc7fff,
 103         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
 104 };
 105
 106 static struct resource video_ram_resource = {
 107         .name   = "Video RAM area",
 108         .start  = 0xa0000,
 109         .end    = 0xbffff,
 110         .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
 111 };
 112
 113 static struct resource standard_io_resources[] = { {
 114         .name   = "dma1",
 115         .start  = 0x0000,
 116         .end    = 0x001f,
 117         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 118 }, {
 119         .name   = "pic1",
 120         .start  = 0x0020,
 121         .end    = 0x0021,
 122         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 123 }, {
 124         .name   = "timer0",
 125         .start  = 0x0040,
 126         .end    = 0x0043,
 127         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 128 }, {
 129         .name   = "timer1",
 130         .start  = 0x0050,
 131         .end    = 0x0053,
 132         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 133 }, {
 134         .name   = "keyboard",
 135         .start  = 0x0060,
 136         .end    = 0x006f,
 137         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 138 }, {
 139         .name   = "dma page reg",
 140         .start  = 0x0080,
 141         .end    = 0x008f,
 142         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 143 }, {
 144         .name   = "pic2",
 145         .start  = 0x00a0,
 146         .end    = 0x00a1,
 147         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 148 }, {
 149         .name   = "dma2",
 150         .start  = 0x00c0,
 151         .end    = 0x00df,
 152         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 153 }, {
 154         .name   = "fpu",
 155         .start  = 0x00f0,
 156         .end    = 0x00ff,
 157         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 158 } };
 159
 160 #define ROMSIGNATURE 0xaa55
 161
 162 static int __init romsignature(const unsigned char *rom)
 163 {
 164         const unsigned short * const ptr = (const unsigned short *)rom;
 165         unsigned short sig;
 166
 167         return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
 168 }
 169
 170 static int __init romchecksum(const unsigned char *rom, unsigned long length)
 171 {
 172         unsigned char sum, c;
 173
 174         for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
 175                 sum += c;
 176         return !length && !sum;
 177 }
 178
 179 static void __init probe_roms(void)
 180 {
 181         const unsigned char *rom;
 182         unsigned long start, length, upper;
 183         unsigned char c;
 184         int i;
 185
 186         /* video rom */
 187         upper = adapter_rom_resources[0].start;
 188         for (start = video_rom_resource.start; start < upper; start += 2048) {
 189                 rom = isa_bus_to_virt(start);
 190                 if (!romsignature(rom))
 191                         continue;
 192
 193                 video_rom_resource.start = start;
 194
 195                 if (probe_kernel_address(rom + 2, c) != 0)
 196                         continue;
 197
 198                 /* 0 < length <= 0x7f * 512, historically */
 199                 length = c * 512;
 200
 201                 /* if checksum okay, trust length byte */
 202                 if (length && romchecksum(rom, length))
 203                         video_rom_resource.end = start + length - 1;
 204
 205                 request_resource(&iomem_resource, &video_rom_resource);
 206                 break;
 207         }
 208
 209         start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
 210         if (start < upper)
 211                 start = upper;
 212
 213         /* system rom */
 214         request_resource(&iomem_resource, &system_rom_resource);
 215         upper = system_rom_resource.start;
 216
 217         /* check for extension rom (ignore length byte!) */
 218         rom = isa_bus_to_virt(extension_rom_resource.start);
 219         if (romsignature(rom)) {
 220                 length = extension_rom_resource.end - extension_rom_resource.start + 1;
 221                 if (romchecksum(rom, length)) {
 222                         request_resource(&iomem_resource, &extension_rom_resource);
 223                         upper = extension_rom_resource.start;
 224                 }
 225         }
 226
 227         /* check for adapter roms on 2k boundaries */
 228         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
 229                 rom = isa_bus_to_virt(start);
 230                 if (!romsignature(rom))
 231                         continue;
 232
 233                 if (probe_kernel_address(rom + 2, c) != 0)
 234                         continue;
 235
 236                 /* 0 < length <= 0x7f * 512, historically */
 237                 length = c * 512;
 238
 239                 /* but accept any length that fits if checksum okay */
 240                 if (!length || start + length > upper || !romchecksum(rom, length))
 241                         continue;
 242
 243                 adapter_rom_resources[i].start = start;
 244                 adapter_rom_resources[i].end = start + length - 1;
 245                 request_resource(&iomem_resource, &adapter_rom_resources[i]);
 246
 247                 start = adapter_rom_resources[i++].end & ~2047UL;
 248         }
 249 }
 250
 251 /*
 252  * Request address space for all standard RAM and ROM resources
 253  * and also for regions reported as reserved by the e820.
 254  */
 255 static void __init
 256 legacy_init_iomem_resources(struct resource *code_resource, struct resource *data_resource)
 257 {
 258         int i;
 259
 260         probe_roms();
 261         for (i = 0; i < e820.nr_map; i++) {
 262                 struct resource *res;
 263 #ifndef CONFIG_RESOURCES_64BIT
 264                 if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
 265                         continue;
 266 #endif
 267                 res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
 268                 switch (e820.map[i].type) {
 269                 case E820_RAM:  res->name = "System RAM"; break;
 270                 case E820_ACPI: res->name = "ACPI Tables"; break;
 271                 case E820_NVS:  res->name = "ACPI Non-volatile Storage"; break;
 272                 default:        res->name = "reserved";
 273                 }
 274                 res->start = e820.map[i].addr;
 275                 res->end = res->start + e820.map[i].size - 1;
 276                 res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 277                 if (request_resource(&iomem_resource, res)) {
 278                         kfree(res);
 279                         continue;
 280                 }
 281                 if (e820.map[i].type == E820_RAM) {
 282                         /*
 283                          *  We don't know which RAM region contains kernel data,
 284                          *  so we try it repeatedly and let the resource manager
 285                          *  test it.
 286                          */
 287                         request_resource(res, code_resource);
 288                         request_resource(res, data_resource);
 289 #ifdef CONFIG_KEXEC
 290                         request_resource(res, &crashk_res);
 291 #endif
 292                 }
 293         }
 294 }
 295
 296 /*
 297  * Request address space for all standard resources
 298  *
 299  * This is called just before pcibios_init(), which is also a
 300  * subsys_initcall, but is linked in later (in arch/i386/pci/common.c).
 301  */
 302 static int __init request_standard_resources(void)
 303 {
 304         int i;
 305
 306         printk("Setting up standard PCI resources\n");
 307         if (efi_enabled)
 308                 efi_initialize_iomem_resources(&code_resource, &data_resource);
 309         else
 310                 legacy_init_iomem_resources(&code_resource, &data_resource);
 311
 312         /* EFI systems may still have VGA */
 313         request_resource(&iomem_resource, &video_ram_resource);
 314
 315         /* request I/O space for devices used on all i[345]86 PCs */
 316         for (i = 0; i < ARRAY_SIZE(standard_io_resources); i++)
 317                 request_resource(&ioport_resource, &standard_io_resources[i]);
 318         return 0;
 319 }
 320
 321 subsys_initcall(request_standard_resources);
 322
 323 void __init add_memory_region(unsigned long long start,
 324                               unsigned long long size, int type)
 325 {
 326         int x;
 327
 328         if (!efi_enabled) {
 329                 x = e820.nr_map;
 330
 331                 if (x == E820MAX) {
 332                     printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
 333                     return;
 334                 }
 335
 336                 e820.map[x].addr = start;
 337                 e820.map[x].size = size;
 338                 e820.map[x].type = type;
 339                 e820.nr_map++;
 340         }
 341 } /* add_memory_region */
 342
 343 /*
 344  * Sanitize the BIOS e820 map.
 345  *
 346  * Some e820 responses include overlapping entries.  The following
 347  * replaces the original e820 map with a new one, removing overlaps.
 348  *
 349  */
 350 int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
 351 {
 352         struct change_member *change_tmp;
 353         unsigned long current_type, last_type;
 354         unsigned long long last_addr;
 355         int chgidx, still_changing;
 356         int overlap_entries;
 357         int new_bios_entry;
 358         int old_nr, new_nr, chg_nr;
 359         int i;
 360
 361         /*
 362                 Visually we're performing the following (1,2,3,4 = memory types)...
 363
 364                 Sample memory map (w/overlaps):
 365                    ____22__________________
 366                    ______________________4_
 367                    ____1111________________
 368                    _44_____________________
 369                    11111111________________
 370                    ____________________33__
 371                    ___________44___________
 372                    __________33333_________
 373                    ______________22________
 374                    ___________________2222_
 375                    _________111111111______
 376                    _____________________11_
 377                    _________________4______
 378
 379                 Sanitized equivalent (no overlap):
 380                    1_______________________
 381                    _44_____________________
 382                    ___1____________________
 383                    ____22__________________
 384                    ______11________________
 385                    _________1______________
 386                    __________3_____________
 387                    ___________44___________
 388                    _____________33_________
 389                    _______________2________
 390                    ________________1_______
 391                    _________________4______
 392                    ___________________2____
 393                    ____________________33__
 394                    ______________________4_
 395         */
 396         /* if there's only one memory region, don't bother */
 397         if (*pnr_map < 2) {
 398                 return -1;
 399         }
 400
 401         old_nr = *pnr_map;
 402
 403         /* bail out if we find any unreasonable addresses in bios map */
 404         for (i=0; i<old_nr; i++)
 405                 if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr) {
 406                         return -1;
 407                 }
 408
 409         /* create pointers for initial change-point information (for sorting) */
 410         for (i=0; i < 2*old_nr; i++)
 411                 change_point[i] = &change_point_list[i];
 412
 413         /* record all known change-points (starting and ending addresses),
 414            omitting those that are for empty memory regions */
 415         chgidx = 0;
 416         for (i=0; i < old_nr; i++)      {
 417                 if (biosmap[i].size != 0) {
 418                         change_point[chgidx]->addr = biosmap[i].addr;
 419                         change_point[chgidx++]->pbios = &biosmap[i];
 420                         change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
 421                         change_point[chgidx++]->pbios = &biosmap[i];
 422                 }
 423         }
 424         chg_nr = chgidx;        /* true number of change-points */
 425
 426         /* sort change-point list by memory addresses (low -> high) */
 427         still_changing = 1;
 428         while (still_changing)  {
 429                 still_changing = 0;
 430                 for (i=1; i < chg_nr; i++)  {
 431                         /* if <current_addr> > <last_addr>, swap */
 432                         /* or, if current=<start_addr> & last=<end_addr>, swap */
 433                         if ((change_point[i]->addr < change_point[i-1]->addr) ||
 434                                 ((change_point[i]->addr == change_point[i-1]->addr) &&
 435                                  (change_point[i]->addr == change_point[i]->pbios->addr) &&
 436                                  (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
 437                            )
 438                         {
 439                                 change_tmp = change_point[i];
 440                                 change_point[i] = change_point[i-1];
 441                                 change_point[i-1] = change_tmp;
 442                                 still_changing=1;
 443                         }
 444                 }
 445         }
 446
 447         /* create a new bios memory map, removing overlaps */
 448         overlap_entries=0;       /* number of entries in the overlap table */
 449         new_bios_entry=0;        /* index for creating new bios map entries */
 450         last_type = 0;           /* start with undefined memory type */
 451         last_addr = 0;           /* start with 0 as last starting address */
 452         /* loop through change-points, determining affect on the new bios map */
 453         for (chgidx=0; chgidx < chg_nr; chgidx++)
 454         {
 455                 /* keep track of all overlapping bios entries */
 456                 if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
 457                 {
 458                         /* add map entry to overlap list (> 1 entry implies an overlap) */
 459                         overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
 460                 }
 461                 else
 462                 {
 463                         /* remove entry from list (order independent, so swap with last) */
 464                         for (i=0; i<overlap_entries; i++)
 465                         {
 466                                 if (overlap_list[i] == change_point[chgidx]->pbios)
 467                                         overlap_list[i] = overlap_list[overlap_entries-1];
 468                         }
 469                         overlap_entries--;
 470                 }
 471                 /* if there are overlapping entries, decide which "type" to use */
 472                 /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
 473                 current_type = 0;
 474                 for (i=0; i<overlap_entries; i++)
 475                         if (overlap_list[i]->type > current_type)
 476                                 current_type = overlap_list[i]->type;
 477                 /* continue building up new bios map based on this information */
 478                 if (current_type != last_type)  {
 479                         if (last_type != 0)      {
 480                                 new_bios[new_bios_entry].size =
 481                                         change_point[chgidx]->addr - last_addr;
 482                                 /* move forward only if the new size was non-zero */
 483                                 if (new_bios[new_bios_entry].size != 0)
 484                                         if (++new_bios_entry >= E820MAX)
 485                                                 break;  /* no more space left for new bios entries */
 486                         }
 487                         if (current_type != 0)  {
 488                                 new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
 489                                 new_bios[new_bios_entry].type = current_type;
 490                                 last_addr=change_point[chgidx]->addr;
 491                         }
 492                         last_type = current_type;
 493                 }
 494         }
 495         new_nr = new_bios_entry;   /* retain count for new bios entries */
 496
 497         /* copy new bios mapping into original location */
 498         memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
 499         *pnr_map = new_nr;
 500
 501         return 0;
 502 }
 503
 504 /*
 505  * Copy the BIOS e820 map into a safe place.
 506  *
 507  * Sanity-check it while we're at it..
 508  *
 509  * If we're lucky and live on a modern system, the setup code
 510  * will have given us a memory map that we can use to properly
 511  * set up memory.  If we aren't, we'll fake a memory map.
 512  *
 513  * We check to see that the memory map contains at least 2 elements
 514  * before we'll use it, because the detection code in setup.S may
 515  * not be perfect and most every PC known to man has two memory
 516  * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
 517  * thinkpad 560x, for example, does not cooperate with the memory
 518  * detection code.)
 519  */
 520 int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
 521 {
 522         /* Only one memory region (or negative)? Ignore it */
 523         if (nr_map < 2)
 524                 return -1;
 525
 526         do {
 527                 unsigned long long start = biosmap->addr;
 528                 unsigned long long size = biosmap->size;
 529                 unsigned long long end = start + size;
 530                 unsigned long type = biosmap->type;
 531
 532                 /* Overflow in 64 bits? Ignore the memory map. */
 533                 if (start > end)
 534                         return -1;
 535
 536                 /*
 537                  * Some BIOSes claim RAM in the 640k - 1M region.
 538                  * Not right. Fix it up.
 539                  */
 540                 if (type == E820_RAM) {
 541                         if (start < 0x100000ULL && end > 0xA0000ULL) {
 542                                 if (start < 0xA0000ULL)
 543                                         add_memory_region(start, 0xA0000ULL-start, type);
 544                                 if (end <= 0x100000ULL)
 545                                         continue;
 546                                 start = 0x100000ULL;
 547                                 size = end - start;
 548                         }
 549                 }
 550                 add_memory_region(start, size, type);
 551         } while (biosmap++,--nr_map);
 552         return 0;
 553 }
 554
 555 /*
 556  * Callback for efi_memory_walk.
 557  */
 558 static int __init
 559 efi_find_max_pfn(unsigned long start, unsigned long end, void *arg)
 560 {
 561         unsigned long *max_pfn = arg, pfn;
 562
 563         if (start < end) {
 564                 pfn = PFN_UP(end -1);
 565                 if (pfn > *max_pfn)
 566                         *max_pfn = pfn;
 567         }
 568         return 0;
 569 }
 570
 571 static int __init
 572 efi_memory_present_wrapper(unsigned long start, unsigned long end, void *arg)
 573 {
 574         memory_present(0, PFN_UP(start), PFN_DOWN(end));
 575         return 0;
 576 }
 577
 578 /*
 579  * Find the highest page frame number we have available
 580  */
 581 void __init find_max_pfn(void)
 582 {
 583         int i;
 584
 585         max_pfn = 0;
 586         if (efi_enabled) {
 587                 efi_memmap_walk(efi_find_max_pfn, &max_pfn);
 588                 efi_memmap_walk(efi_memory_present_wrapper, NULL);
 589                 return;
 590         }
 591
 592         for (i = 0; i < e820.nr_map; i++) {
 593                 unsigned long start, end;
 594                 /* RAM? */
 595                 if (e820.map[i].type != E820_RAM)
 596                         continue;
 597                 start = PFN_UP(e820.map[i].addr);
 598                 end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
 599                 if (start >= end)
 600                         continue;
 601                 if (end > max_pfn)
 602                         max_pfn = end;
 603                 memory_present(0, start, end);
 604         }
 605 }
 606
 607 /*
 608  * Free all available memory for boot time allocation.  Used
 609  * as a callback function by efi_memory_walk()
 610  */
 611
 612 static int __init
 613 free_available_memory(unsigned long start, unsigned long end, void *arg)
 614 {
 615         /* check max_low_pfn */
 616         if (start >= (max_low_pfn << PAGE_SHIFT))
 617                 return 0;
 618         if (end >= (max_low_pfn << PAGE_SHIFT))
 619                 end = max_low_pfn << PAGE_SHIFT;
 620         if (start < end)
 621                 free_bootmem(start, end - start);
 622
 623         return 0;
 624 }
 625 /*
 626  * Register fully available low RAM pages with the bootmem allocator.
 627  */
 628 void __init register_bootmem_low_pages(unsigned long max_low_pfn)
 629 {
 630         int i;
 631
 632         if (efi_enabled) {
 633                 efi_memmap_walk(free_available_memory, NULL);
 634                 return;
 635         }
 636         for (i = 0; i < e820.nr_map; i++) {
 637                 unsigned long curr_pfn, last_pfn, size;
 638                 /*
 639                  * Reserve usable low memory
 640                  */
 641                 if (e820.map[i].type != E820_RAM)
 642                         continue;
 643                 /*
 644                  * We are rounding up the start address of usable memory:
 645                  */
 646                 curr_pfn = PFN_UP(e820.map[i].addr);
 647                 if (curr_pfn >= max_low_pfn)
 648                         continue;
 649                 /*
 650                  * ... and at the end of the usable range downwards:
 651                  */
 652                 last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
 653
 654                 if (last_pfn > max_low_pfn)
 655                         last_pfn = max_low_pfn;
 656
 657                 /*
 658                  * .. finally, did all the rounding and playing
 659                  * around just make the area go away?
 660                  */
 661                 if (last_pfn <= curr_pfn)
 662                         continue;
 663
 664                 size = last_pfn - curr_pfn;
 665                 free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
 666         }
 667 }
 668
 669 void __init e820_register_memory(void)
 670 {
 671         unsigned long gapstart, gapsize, round;
 672         unsigned long long last;
 673         int i;
 674
 675         /*
 676          * Search for the bigest gap in the low 32 bits of the e820
 677          * memory space.
 678          */
 679         last = 0x100000000ull;
 680         gapstart = 0x10000000;
 681         gapsize = 0x400000;
 682         i = e820.nr_map;
 683         while (--i >= 0) {
 684                 unsigned long long start = e820.map[i].addr;
 685                 unsigned long long end = start + e820.map[i].size;
 686
 687                 /*
 688                  * Since "last" is at most 4GB, we know we'll
 689                  * fit in 32 bits if this condition is true
 690                  */
 691                 if (last > end) {
 692                         unsigned long gap = last - end;
 693
 694                         if (gap > gapsize) {
 695                                 gapsize = gap;
 696                                 gapstart = end;
 697                         }
 698                 }
 699                 if (start < last)
 700                         last = start;
 701         }
 702
 703         /*
 704          * See how much we want to round up: start off with
 705          * rounding to the next 1MB area.
 706          */
 707         round = 0x100000;
 708         while ((gapsize >> 4) > round)
 709                 round += round;
 710         /* Fun with two's complement */
 711         pci_mem_start = (gapstart + round) & -round;
 712
 713         printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
 714                 pci_mem_start, gapstart, gapsize);
 715 }
 716
 717 void __init print_memory_map(char *who)
 718 {
 719         int i;
 720
 721         for (i = 0; i < e820.nr_map; i++) {
 722                 printk(" %s: %016Lx - %016Lx ", who,
 723                         e820.map[i].addr,
 724                         e820.map[i].addr + e820.map[i].size);
 725                 switch (e820.map[i].type) {
 726                 case E820_RAM:  printk("(usable)\n");
 727                                 break;
 728                 case E820_RESERVED:
 729                                 printk("(reserved)\n");
 730                                 break;
 731                 case E820_ACPI:
 732                                 printk("(ACPI data)\n");
 733                                 break;
 734                 case E820_NVS:
 735                                 printk("(ACPI NVS)\n");
 736                                 break;
 737                 default:        printk("type %u\n", e820.map[i].type);
 738                                 break;
 739                 }
 740         }
 741 }
 742
 743 static __init __always_inline void efi_limit_regions(unsigned long long size)
 744 {
 745         unsigned long long current_addr = 0;
 746         efi_memory_desc_t *md, *next_md;
 747         void *p, *p1;
 748         int i, j;
 749
 750         j = 0;
 751         p1 = memmap.map;
 752         for (p = p1, i = 0; p < memmap.map_end; p += memmap.desc_size, i++) {
 753                 md = p;
 754                 next_md = p1;
 755                 current_addr = md->phys_addr +
 756                         PFN_PHYS(md->num_pages);
 757                 if (is_available_memory(md)) {
 758                         if (md->phys_addr >= size) continue;
 759                         memcpy(next_md, md, memmap.desc_size);
 760                         if (current_addr >= size) {
 761                                 next_md->num_pages -=
 762                                         PFN_UP(current_addr-size);
 763                         }
 764                         p1 += memmap.desc_size;
 765                         next_md = p1;
 766                         j++;
 767                 } else if ((md->attribute & EFI_MEMORY_RUNTIME) ==
 768                            EFI_MEMORY_RUNTIME) {
 769                         /* In order to make runtime services
 770                          * available we have to include runtime
 771                          * memory regions in memory map */
 772                         memcpy(next_md, md, memmap.desc_size);
 773                         p1 += memmap.desc_size;
 774                         next_md = p1;
 775                         j++;
 776                 }
 777         }
 778         memmap.nr_map = j;
 779         memmap.map_end = memmap.map +
 780                 (memmap.nr_map * memmap.desc_size);
 781 }
 782
 783 void __init limit_regions(unsigned long long size)
 784 {
 785         unsigned long long current_addr;
 786         int i;
 787
 788         print_memory_map("limit_regions start");
 789         if (efi_enabled) {
 790                 efi_limit_regions(size);
 791                 return;
 792         }
 793         for (i = 0; i < e820.nr_map; i++) {
 794                 current_addr = e820.map[i].addr + e820.map[i].size;
 795                 if (current_addr < size)
 796                         continue;
 797
 798                 if (e820.map[i].type != E820_RAM)
 799                         continue;
 800
 801                 if (e820.map[i].addr >= size) {
 802                         /*
 803                          * This region starts past the end of the
 804                          * requested size, skip it completely.
 805                          */
 806                         e820.nr_map = i;
 807                 } else {
 808                         e820.nr_map = i + 1;
 809                         e820.map[i].size -= current_addr - size;
 810                 }
 811                 print_memory_map("limit_regions endfor");
 812                 return;
 813         }
 814         print_memory_map("limit_regions endfunc");
 815 }
 816
 817 /*
 818  * This function checks if any part of the range <start,end> is mapped
 819  * with type.
 820  */
 821 int
 822 e820_any_mapped(u64 start, u64 end, unsigned type)
 823 {
 824         int i;
 825         for (i = 0; i < e820.nr_map; i++) {
 826                 const struct e820entry *ei = &e820.map[i];
 827                 if (type && ei->type != type)
 828                         continue;
 829                 if (ei->addr >= end || ei->addr + ei->size <= start)
 830                         continue;
 831                 return 1;
 832         }
 833         return 0;
 834 }
 835 EXPORT_SYMBOL_GPL(e820_any_mapped);
 836
 837  /*
 838   * This function checks if the entire range <start,end> is mapped with type.
 839   *
 840   * Note: this function only works correct if the e820 table is sorted and
 841   * not-overlapping, which is the case
 842   */
 843 int __init
 844 e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
 845 {
 846         u64 start = s;
 847         u64 end = e;
 848         int i;
 849         for (i = 0; i < e820.nr_map; i++) {
 850                 struct e820entry *ei = &e820.map[i];
 851                 if (type && ei->type != type)
 852                         continue;
 853                 /* is the region (part) in overlap with the current region ?*/
 854                 if (ei->addr >= end || ei->addr + ei->size <= start)
 855                         continue;
 856                 /* if the region is at the beginning of <start,end> we move
 857                  * start to the end of the region since it's ok until there
 858                  */
 859                 if (ei->addr <= start)
 860                         start = ei->addr + ei->size;
 861                 /* if start is now at or beyond end, we're done, full
 862                  * coverage */
 863                 if (start >= end)
 864                         return 1; /* we're done */
 865         }
 866         return 0;
 867 }
 868
 869 static int __init parse_memmap(char *arg)
 870 {
 871         if (!arg)
 872                 return -EINVAL;
 873
 874         if (strcmp(arg, "exactmap") == 0) {
 875 #ifdef CONFIG_CRASH_DUMP
 876                 /* If we are doing a crash dump, we
 877                  * still need to know the real mem
 878                  * size before original memory map is
 879                  * reset.
 880                  */
 881                 find_max_pfn();
 882                 saved_max_pfn = max_pfn;
 883 #endif
 884                 e820.nr_map = 0;
 885                 user_defined_memmap = 1;
 886         } else {
 887                 /* If the user specifies memory size, we
 888                  * limit the BIOS-provided memory map to
 889                  * that size. exactmap can be used to specify
 890                  * the exact map. mem=number can be used to
 891                  * trim the existing memory map.
 892                  */
 893                 unsigned long long start_at, mem_size;
 894
 895                 mem_size = memparse(arg, &arg);
 896                 if (*arg == '@') {
 897                         start_at = memparse(arg+1, &arg);
 898                         add_memory_region(start_at, mem_size, E820_RAM);
 899                 } else if (*arg == '#') {
 900                         start_at = memparse(arg+1, &arg);
 901                         add_memory_region(start_at, mem_size, E820_ACPI);
 902                 } else if (*arg == '$') {
 903                         start_at = memparse(arg+1, &arg);
 904                         add_memory_region(start_at, mem_size, E820_RESERVED);
 905                 } else {
 906                         limit_regions(mem_size);
 907                         user_defined_memmap = 1;
 908                 }
 909         }
 910         return 0;
 911 }
 912 early_param("memmap", parse_memmap);