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