arch/x86/mm/numa_64.c

   1 /*
   2  * Generic VM initialization for x86-64 NUMA setups.
   3  * Copyright 2002,2003 Andi Kleen, SuSE Labs.
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/mm.h>
   7 #include <linux/string.h>
   8 #include <linux/init.h>
   9 #include <linux/bootmem.h>
  10 #include <linux/mmzone.h>
  11 #include <linux/ctype.h>
  12 #include <linux/module.h>
  13 #include <linux/nodemask.h>
  14 #include <linux/sched.h>
  15
  16 #include <asm/e820.h>
  17 #include <asm/proto.h>
  18 #include <asm/dma.h>
  19 #include <asm/numa.h>
  20 #include <asm/acpi.h>
  21 #include <asm/k8.h>
  22
  23 #ifndef Dprintk
  24 #define Dprintk(x...)
  25 #endif
  26
  27 struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
  28 EXPORT_SYMBOL(node_data);
  29
  30 bootmem_data_t plat_node_bdata[MAX_NUMNODES];
  31
  32 struct memnode memnode;
  33
  34 #ifdef CONFIG_SMP
  35 int x86_cpu_to_node_map_init[NR_CPUS] = {
  36         [0 ... NR_CPUS-1] = NUMA_NO_NODE
  37 };
  38 void *x86_cpu_to_node_map_early_ptr;
  39 EXPORT_SYMBOL(x86_cpu_to_node_map_early_ptr);
  40 #endif
  41 DEFINE_PER_CPU(int, x86_cpu_to_node_map) = NUMA_NO_NODE;
  42 EXPORT_PER_CPU_SYMBOL(x86_cpu_to_node_map);
  43
  44 s16 apicid_to_node[MAX_LOCAL_APIC] __cpuinitdata = {
  45         [0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
  46 };
  47
  48 cpumask_t node_to_cpumask_map[MAX_NUMNODES] __read_mostly;
  49 EXPORT_SYMBOL(node_to_cpumask_map);
  50
  51 int numa_off __initdata;
  52 unsigned long __initdata nodemap_addr;
  53 unsigned long __initdata nodemap_size;
  54
  55 /*
  56  * Given a shift value, try to populate memnodemap[]
  57  * Returns :
  58  * 1 if OK
  59  * 0 if memnodmap[] too small (of shift too small)
  60  * -1 if node overlap or lost ram (shift too big)
  61  */
  62 static int __init populate_memnodemap(const struct bootnode *nodes,
  63                                       int numnodes, int shift, int *nodeids)
  64 {
  65         unsigned long addr, end;
  66         int i, res = -1;
  67
  68         memset(memnodemap, 0xff, sizeof(s16)*memnodemapsize);
  69         for (i = 0; i < numnodes; i++) {
  70                 addr = nodes[i].start;
  71                 end = nodes[i].end;
  72                 if (addr >= end)
  73                         continue;
  74                 if ((end >> shift) >= memnodemapsize)
  75                         return 0;
  76                 do {
  77                         if (memnodemap[addr >> shift] != NUMA_NO_NODE)
  78                                 return -1;
  79
  80                         if (!nodeids)
  81                                 memnodemap[addr >> shift] = i;
  82                         else
  83                                 memnodemap[addr >> shift] = nodeids[i];
  84
  85                         addr += (1UL << shift);
  86                 } while (addr < end);
  87                 res = 1;
  88         }
  89         return res;
  90 }
  91
  92 static int __init allocate_cachealigned_memnodemap(void)
  93 {
  94         unsigned long addr;
  95
  96         memnodemap = memnode.embedded_map;
  97         if (memnodemapsize <= ARRAY_SIZE(memnode.embedded_map))
  98                 return 0;
  99
 100         addr = 0x8000;
 101         nodemap_size = round_up(sizeof(s16) * memnodemapsize, L1_CACHE_BYTES);
 102         nodemap_addr = find_e820_area(addr, end_pfn<<PAGE_SHIFT,
 103                                       nodemap_size, L1_CACHE_BYTES);
 104         if (nodemap_addr == -1UL) {
 105                 printk(KERN_ERR
 106                        "NUMA: Unable to allocate Memory to Node hash map\n");
 107                 nodemap_addr = nodemap_size = 0;
 108                 return -1;
 109         }
 110         memnodemap = phys_to_virt(nodemap_addr);
 111         reserve_early(nodemap_addr, nodemap_addr + nodemap_size, "MEMNODEMAP");
 112
 113         printk(KERN_DEBUG "NUMA: Allocated memnodemap from %lx - %lx\n",
 114                nodemap_addr, nodemap_addr + nodemap_size);
 115         return 0;
 116 }
 117
 118 /*
 119  * The LSB of all start and end addresses in the node map is the value of the
 120  * maximum possible shift.
 121  */
 122 static int __init extract_lsb_from_nodes(const struct bootnode *nodes,
 123                                          int numnodes)
 124 {
 125         int i, nodes_used = 0;
 126         unsigned long start, end;
 127         unsigned long bitfield = 0, memtop = 0;
 128
 129         for (i = 0; i < numnodes; i++) {
 130                 start = nodes[i].start;
 131                 end = nodes[i].end;
 132                 if (start >= end)
 133                         continue;
 134                 bitfield |= start;
 135                 nodes_used++;
 136                 if (end > memtop)
 137                         memtop = end;
 138         }
 139         if (nodes_used <= 1)
 140                 i = 63;
 141         else
 142                 i = find_first_bit(&bitfield, sizeof(unsigned long)*8);
 143         memnodemapsize = (memtop >> i)+1;
 144         return i;
 145 }
 146
 147 int __init compute_hash_shift(struct bootnode *nodes, int numnodes,
 148                               int *nodeids)
 149 {
 150         int shift;
 151
 152         shift = extract_lsb_from_nodes(nodes, numnodes);
 153         if (allocate_cachealigned_memnodemap())
 154                 return -1;
 155         printk(KERN_DEBUG "NUMA: Using %d for the hash shift.\n",
 156                 shift);
 157
 158         if (populate_memnodemap(nodes, numnodes, shift, nodeids) != 1) {
 159                 printk(KERN_INFO "Your memory is not aligned you need to "
 160                        "rebuild your kernel with a bigger NODEMAPSIZE "
 161                        "shift=%d\n", shift);
 162                 return -1;
 163         }
 164         return shift;
 165 }
 166
 167 int early_pfn_to_nid(unsigned long pfn)
 168 {
 169         return phys_to_nid(pfn << PAGE_SHIFT);
 170 }
 171
 172 static void * __init early_node_mem(int nodeid, unsigned long start,
 173                                     unsigned long end, unsigned long size,
 174                                     unsigned long align)
 175 {
 176         unsigned long mem = find_e820_area(start, end, size, align);
 177         void *ptr;
 178
 179         if (mem != -1L)
 180                 return __va(mem);
 181
 182         ptr = __alloc_bootmem_nopanic(size, align, __pa(MAX_DMA_ADDRESS));
 183         if (ptr == NULL) {
 184                 printk(KERN_ERR "Cannot find %lu bytes in node %d\n",
 185                        size, nodeid);
 186                 return NULL;
 187         }
 188         return ptr;
 189 }
 190
 191 /* Initialize bootmem allocator for a node */
 192 void __init setup_node_bootmem(int nodeid, unsigned long start,
 193                                unsigned long end)
 194 {
 195         unsigned long start_pfn, end_pfn, bootmap_pages, bootmap_size;
 196         unsigned long bootmap_start, nodedata_phys;
 197         void *bootmap;
 198         const int pgdat_size = round_up(sizeof(pg_data_t), PAGE_SIZE);
 199
 200         start = round_up(start, ZONE_ALIGN);
 201
 202         printk(KERN_INFO "Bootmem setup node %d %016lx-%016lx\n", nodeid,
 203                start, end);
 204
 205         start_pfn = start >> PAGE_SHIFT;
 206         end_pfn = end >> PAGE_SHIFT;
 207
 208         node_data[nodeid] = early_node_mem(nodeid, start, end, pgdat_size,
 209                                            SMP_CACHE_BYTES);
 210         if (node_data[nodeid] == NULL)
 211                 return;
 212         nodedata_phys = __pa(node_data[nodeid]);
 213         printk(KERN_INFO "  NODE_DATA [%016lx - %016lx]\n", nodedata_phys,
 214                 nodedata_phys + pgdat_size - 1);
 215
 216         memset(NODE_DATA(nodeid), 0, sizeof(pg_data_t));
 217         NODE_DATA(nodeid)->bdata = &plat_node_bdata[nodeid];
 218         NODE_DATA(nodeid)->node_start_pfn = start_pfn;
 219         NODE_DATA(nodeid)->node_spanned_pages = end_pfn - start_pfn;
 220
 221         /* Find a place for the bootmem map */
 222         bootmap_pages = bootmem_bootmap_pages(end_pfn - start_pfn);
 223         bootmap_start = round_up(nodedata_phys + pgdat_size, PAGE_SIZE);
 224         /*
 225          * SMP_CAHCE_BYTES could be enough, but init_bootmem_node like
 226          * to use that to align to PAGE_SIZE
 227          */
 228         bootmap = early_node_mem(nodeid, bootmap_start, end,
 229                                  bootmap_pages<<PAGE_SHIFT, PAGE_SIZE);
 230         if (bootmap == NULL)  {
 231                 if (nodedata_phys < start || nodedata_phys >= end)
 232                         free_bootmem(nodedata_phys, pgdat_size);
 233                 node_data[nodeid] = NULL;
 234                 return;
 235         }
 236         bootmap_start = __pa(bootmap);
 237
 238         bootmap_size = init_bootmem_node(NODE_DATA(nodeid),
 239                                          bootmap_start >> PAGE_SHIFT,
 240                                          start_pfn, end_pfn);
 241
 242         printk(KERN_INFO "  bootmap [%016lx -  %016lx] pages %lx\n",
 243                  bootmap_start, bootmap_start + bootmap_size - 1,
 244                  bootmap_pages);
 245
 246         free_bootmem_with_active_regions(nodeid, end);
 247
 248         reserve_bootmem_node(NODE_DATA(nodeid), nodedata_phys, pgdat_size,
 249                         BOOTMEM_DEFAULT);
 250         reserve_bootmem_node(NODE_DATA(nodeid), bootmap_start,
 251                         bootmap_pages<<PAGE_SHIFT, BOOTMEM_DEFAULT);
 252 #ifdef CONFIG_ACPI_NUMA
 253         srat_reserve_add_area(nodeid);
 254 #endif
 255         node_set_online(nodeid);
 256 }
 257
 258 /*
 259  * There are unfortunately some poorly designed mainboards around that
 260  * only connect memory to a single CPU. This breaks the 1:1 cpu->node
 261  * mapping. To avoid this fill in the mapping for all possible CPUs,
 262  * as the number of CPUs is not known yet. We round robin the existing
 263  * nodes.
 264  */
 265 void __init numa_init_array(void)
 266 {
 267         int rr, i;
 268
 269         rr = first_node(node_online_map);
 270         for (i = 0; i < NR_CPUS; i++) {
 271                 if (early_cpu_to_node(i) != NUMA_NO_NODE)
 272                         continue;
 273                 numa_set_node(i, rr);
 274                 rr = next_node(rr, node_online_map);
 275                 if (rr == MAX_NUMNODES)
 276                         rr = first_node(node_online_map);
 277         }
 278 }
 279
 280 #ifdef CONFIG_NUMA_EMU
 281 /* Numa emulation */
 282 char *cmdline __initdata;
 283
 284 /*
 285  * Setups up nid to range from addr to addr + size.  If the end
 286  * boundary is greater than max_addr, then max_addr is used instead.
 287  * The return value is 0 if there is additional memory left for
 288  * allocation past addr and -1 otherwise.  addr is adjusted to be at
 289  * the end of the node.
 290  */
 291 static int __init setup_node_range(int nid, struct bootnode *nodes, u64 *addr,
 292                                    u64 size, u64 max_addr)
 293 {
 294         int ret = 0;
 295
 296         nodes[nid].start = *addr;
 297         *addr += size;
 298         if (*addr >= max_addr) {
 299                 *addr = max_addr;
 300                 ret = -1;
 301         }
 302         nodes[nid].end = *addr;
 303         node_set(nid, node_possible_map);
 304         printk(KERN_INFO "Faking node %d at %016Lx-%016Lx (%LuMB)\n", nid,
 305                nodes[nid].start, nodes[nid].end,
 306                (nodes[nid].end - nodes[nid].start) >> 20);
 307         return ret;
 308 }
 309
 310 /*
 311  * Splits num_nodes nodes up equally starting at node_start.  The return value
 312  * is the number of nodes split up and addr is adjusted to be at the end of the
 313  * last node allocated.
 314  */
 315 static int __init split_nodes_equally(struct bootnode *nodes, u64 *addr,
 316                                       u64 max_addr, int node_start,
 317                                       int num_nodes)
 318 {
 319         unsigned int big;
 320         u64 size;
 321         int i;
 322
 323         if (num_nodes <= 0)
 324                 return -1;
 325         if (num_nodes > MAX_NUMNODES)
 326                 num_nodes = MAX_NUMNODES;
 327         size = (max_addr - *addr - e820_hole_size(*addr, max_addr)) /
 328                num_nodes;
 329         /*
 330          * Calculate the number of big nodes that can be allocated as a result
 331          * of consolidating the leftovers.
 332          */
 333         big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * num_nodes) /
 334               FAKE_NODE_MIN_SIZE;
 335
 336         /* Round down to nearest FAKE_NODE_MIN_SIZE. */
 337         size &= FAKE_NODE_MIN_HASH_MASK;
 338         if (!size) {
 339                 printk(KERN_ERR "Not enough memory for each node.  "
 340                        "NUMA emulation disabled.\n");
 341                 return -1;
 342         }
 343
 344         for (i = node_start; i < num_nodes + node_start; i++) {
 345                 u64 end = *addr + size;
 346
 347                 if (i < big)
 348                         end += FAKE_NODE_MIN_SIZE;
 349                 /*
 350                  * The final node can have the remaining system RAM.  Other
 351                  * nodes receive roughly the same amount of available pages.
 352                  */
 353                 if (i == num_nodes + node_start - 1)
 354                         end = max_addr;
 355                 else
 356                         while (end - *addr - e820_hole_size(*addr, end) <
 357                                size) {
 358                                 end += FAKE_NODE_MIN_SIZE;
 359                                 if (end > max_addr) {
 360                                         end = max_addr;
 361                                         break;
 362                                 }
 363                         }
 364                 if (setup_node_range(i, nodes, addr, end - *addr, max_addr) < 0)
 365                         break;
 366         }
 367         return i - node_start + 1;
 368 }
 369
 370 /*
 371  * Splits the remaining system RAM into chunks of size.  The remaining memory is
 372  * always assigned to a final node and can be asymmetric.  Returns the number of
 373  * nodes split.
 374  */
 375 static int __init split_nodes_by_size(struct bootnode *nodes, u64 *addr,
 376                                       u64 max_addr, int node_start, u64 size)
 377 {
 378         int i = node_start;
 379         size = (size << 20) & FAKE_NODE_MIN_HASH_MASK;
 380         while (!setup_node_range(i++, nodes, addr, size, max_addr))
 381                 ;
 382         return i - node_start;
 383 }
 384
 385 /*
 386  * Sets up the system RAM area from start_pfn to end_pfn according to the
 387  * numa=fake command-line option.
 388  */
 389 static int __init numa_emulation(unsigned long start_pfn, unsigned long end_pfn)
 390 {
 391         struct bootnode nodes[MAX_NUMNODES];
 392         u64 size, addr = start_pfn << PAGE_SHIFT;
 393         u64 max_addr = end_pfn << PAGE_SHIFT;
 394         int num_nodes = 0, num = 0, coeff_flag, coeff = -1, i;
 395
 396         memset(&nodes, 0, sizeof(nodes));
 397         /*
 398          * If the numa=fake command-line is just a single number N, split the
 399          * system RAM into N fake nodes.
 400          */
 401         if (!strchr(cmdline, '*') && !strchr(cmdline, ',')) {
 402                 long n = simple_strtol(cmdline, NULL, 0);
 403
 404                 num_nodes = split_nodes_equally(nodes, &addr, max_addr, 0, n);
 405                 if (num_nodes < 0)
 406                         return num_nodes;
 407                 goto out;
 408         }
 409
 410         /* Parse the command line. */
 411         for (coeff_flag = 0; ; cmdline++) {
 412                 if (*cmdline && isdigit(*cmdline)) {
 413                         num = num * 10 + *cmdline - '0';
 414                         continue;
 415                 }
 416                 if (*cmdline == '*') {
 417                         if (num > 0)
 418                                 coeff = num;
 419                         coeff_flag = 1;
 420                 }
 421                 if (!*cmdline || *cmdline == ',') {
 422                         if (!coeff_flag)
 423                                 coeff = 1;
 424                         /*
 425                          * Round down to the nearest FAKE_NODE_MIN_SIZE.
 426                          * Command-line coefficients are in megabytes.
 427                          */
 428                         size = ((u64)num << 20) & FAKE_NODE_MIN_HASH_MASK;
 429                         if (size)
 430                                 for (i = 0; i < coeff; i++, num_nodes++)
 431                                         if (setup_node_range(num_nodes, nodes,
 432                                                 &addr, size, max_addr) < 0)
 433                                                 goto done;
 434                         if (!*cmdline)
 435                                 break;
 436                         coeff_flag = 0;
 437                         coeff = -1;
 438                 }
 439                 num = 0;
 440         }
 441 done:
 442         if (!num_nodes)
 443                 return -1;
 444         /* Fill remainder of system RAM, if appropriate. */
 445         if (addr < max_addr) {
 446                 if (coeff_flag && coeff < 0) {
 447                         /* Split remaining nodes into num-sized chunks */
 448                         num_nodes += split_nodes_by_size(nodes, &addr, max_addr,
 449                                                          num_nodes, num);
 450                         goto out;
 451                 }
 452                 switch (*(cmdline - 1)) {
 453                 case '*':
 454                         /* Split remaining nodes into coeff chunks */
 455                         if (coeff <= 0)
 456                                 break;
 457                         num_nodes += split_nodes_equally(nodes, &addr, max_addr,
 458                                                          num_nodes, coeff);
 459                         break;
 460                 case ',':
 461                         /* Do not allocate remaining system RAM */
 462                         break;
 463                 default:
 464                         /* Give one final node */
 465                         setup_node_range(num_nodes, nodes, &addr,
 466                                          max_addr - addr, max_addr);
 467                         num_nodes++;
 468                 }
 469         }
 470 out:
 471         memnode_shift = compute_hash_shift(nodes, num_nodes, NULL);
 472         if (memnode_shift < 0) {
 473                 memnode_shift = 0;
 474                 printk(KERN_ERR "No NUMA hash function found.  NUMA emulation "
 475                        "disabled.\n");
 476                 return -1;
 477         }
 478
 479         /*
 480          * We need to vacate all active ranges that may have been registered by
 481          * SRAT and set acpi_numa to -1 so that srat_disabled() always returns
 482          * true.  NUMA emulation has succeeded so we will not scan ACPI nodes.
 483          */
 484         remove_all_active_ranges();
 485 #ifdef CONFIG_ACPI_NUMA
 486         acpi_numa = -1;
 487 #endif
 488         for_each_node_mask(i, node_possible_map) {
 489                 e820_register_active_regions(i, nodes[i].start >> PAGE_SHIFT,
 490                                                 nodes[i].end >> PAGE_SHIFT);
 491                 setup_node_bootmem(i, nodes[i].start, nodes[i].end);
 492         }
 493         acpi_fake_nodes(nodes, num_nodes);
 494         numa_init_array();
 495         return 0;
 496 }
 497 #endif /* CONFIG_NUMA_EMU */
 498
 499 void __init numa_initmem_init(unsigned long start_pfn, unsigned long end_pfn)
 500 {
 501         int i;
 502
 503         nodes_clear(node_possible_map);
 504         nodes_clear(node_online_map);
 505
 506 #ifdef CONFIG_NUMA_EMU
 507         if (cmdline && !numa_emulation(start_pfn, end_pfn))
 508                 return;
 509         nodes_clear(node_possible_map);
 510         nodes_clear(node_online_map);
 511 #endif
 512
 513 #ifdef CONFIG_ACPI_NUMA
 514         if (!numa_off && !acpi_scan_nodes(start_pfn << PAGE_SHIFT,
 515                                           end_pfn << PAGE_SHIFT))
 516                 return;
 517         nodes_clear(node_possible_map);
 518         nodes_clear(node_online_map);
 519 #endif
 520
 521 #ifdef CONFIG_K8_NUMA
 522         if (!numa_off && !k8_scan_nodes(start_pfn<<PAGE_SHIFT,
 523                                         end_pfn<<PAGE_SHIFT))
 524                 return;
 525         nodes_clear(node_possible_map);
 526         nodes_clear(node_online_map);
 527 #endif
 528         printk(KERN_INFO "%s\n",
 529                numa_off ? "NUMA turned off" : "No NUMA configuration found");
 530
 531         printk(KERN_INFO "Faking a node at %016lx-%016lx\n",
 532                start_pfn << PAGE_SHIFT,
 533                end_pfn << PAGE_SHIFT);
 534         /* setup dummy node covering all memory */
 535         memnode_shift = 63;
 536         memnodemap = memnode.embedded_map;
 537         memnodemap[0] = 0;
 538         node_set_online(0);
 539         node_set(0, node_possible_map);
 540         for (i = 0; i < NR_CPUS; i++)
 541                 numa_set_node(i, 0);
 542         /* cpumask_of_cpu() may not be available during early startup */
 543         memset(&node_to_cpumask_map[0], 0, sizeof(node_to_cpumask_map[0]));
 544         cpu_set(0, node_to_cpumask_map[0]);
 545         e820_register_active_regions(0, start_pfn, end_pfn);
 546         setup_node_bootmem(0, start_pfn << PAGE_SHIFT, end_pfn << PAGE_SHIFT);
 547 }
 548
 549 __cpuinit void numa_add_cpu(int cpu)
 550 {
 551         set_bit(cpu,
 552                 (unsigned long *)&node_to_cpumask_map[early_cpu_to_node(cpu)]);
 553 }
 554
 555 void __cpuinit numa_set_node(int cpu, int node)
 556 {
 557         int *cpu_to_node_map = x86_cpu_to_node_map_early_ptr;
 558
 559         if(cpu_to_node_map)
 560                 cpu_to_node_map[cpu] = node;
 561         else if(per_cpu_offset(cpu))
 562                 per_cpu(x86_cpu_to_node_map, cpu) = node;
 563         else
 564                 Dprintk(KERN_INFO "Setting node for non-present cpu %d\n", cpu);
 565 }
 566
 567 unsigned long __init numa_free_all_bootmem(void)
 568 {
 569         unsigned long pages = 0;
 570         int i;
 571
 572         for_each_online_node(i)
 573                 pages += free_all_bootmem_node(NODE_DATA(i));
 574
 575         return pages;
 576 }
 577
 578 void __init paging_init(void)
 579 {
 580         unsigned long max_zone_pfns[MAX_NR_ZONES];
 581
 582         memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 583         max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;
 584         max_zone_pfns[ZONE_DMA32] = MAX_DMA32_PFN;
 585         max_zone_pfns[ZONE_NORMAL] = end_pfn;
 586
 587         sparse_memory_present_with_active_regions(MAX_NUMNODES);
 588         sparse_init();
 589
 590         free_area_init_nodes(max_zone_pfns);
 591 }
 592
 593 static __init int numa_setup(char *opt)
 594 {
 595         if (!opt)
 596                 return -EINVAL;
 597         if (!strncmp(opt, "off", 3))
 598                 numa_off = 1;
 599 #ifdef CONFIG_NUMA_EMU
 600         if (!strncmp(opt, "fake=", 5))
 601                 cmdline = opt + 5;
 602 #endif
 603 #ifdef CONFIG_ACPI_NUMA
 604         if (!strncmp(opt, "noacpi", 6))
 605                 acpi_numa = -1;
 606         if (!strncmp(opt, "hotadd=", 7))
 607                 hotadd_percent = simple_strtoul(opt+7, NULL, 10);
 608 #endif
 609         return 0;
 610 }
 611 early_param("numa", numa_setup);
 612
 613 /*
 614  * Setup early cpu_to_node.
 615  *
 616  * Populate cpu_to_node[] only if x86_cpu_to_apicid[],
 617  * and apicid_to_node[] tables have valid entries for a CPU.
 618  * This means we skip cpu_to_node[] initialisation for NUMA
 619  * emulation and faking node case (when running a kernel compiled
 620  * for NUMA on a non NUMA box), which is OK as cpu_to_node[]
 621  * is already initialized in a round robin manner at numa_init_array,
 622  * prior to this call, and this initialization is good enough
 623  * for the fake NUMA cases.
 624  */
 625 void __init init_cpu_to_node(void)
 626 {
 627         int i;
 628
 629         for (i = 0; i < NR_CPUS; i++) {
 630                 int node;
 631                 u16 apicid = x86_cpu_to_apicid_init[i];
 632
 633                 if (apicid == BAD_APICID)
 634                         continue;
 635                 node = apicid_to_node[apicid];
 636                 if (node == NUMA_NO_NODE)
 637                         continue;
 638                 if (!node_online(node))
 639                         continue;
 640                 numa_set_node(i, node);
 641         }
 642 }
 643
 644