xref: /openbmc/linux/arch/powerpc/mm/numa.c (revision 3e66c4def14aa64ee6d1d4ef077d789abc30125d)
1 /*
2  * pSeries NUMA support
3  *
4  * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 #include <linux/threads.h>
12 #include <linux/bootmem.h>
13 #include <linux/init.h>
14 #include <linux/mm.h>
15 #include <linux/mmzone.h>
16 #include <linux/module.h>
17 #include <linux/nodemask.h>
18 #include <linux/cpu.h>
19 #include <linux/notifier.h>
20 #include <asm/lmb.h>
21 #include <asm/machdep.h>
22 #include <asm/abs_addr.h>
23 #include <asm/system.h>
24 #include <asm/smp.h>
25 
26 static int numa_enabled = 1;
27 
28 static int numa_debug;
29 #define dbg(args...) if (numa_debug) { printk(KERN_INFO args); }
30 
31 #ifdef DEBUG_NUMA
32 #define ARRAY_INITIALISER -1
33 #else
34 #define ARRAY_INITIALISER 0
35 #endif
36 
37 int numa_cpu_lookup_table[NR_CPUS] = { [ 0 ... (NR_CPUS - 1)] =
38 	ARRAY_INITIALISER};
39 char *numa_memory_lookup_table;
40 cpumask_t numa_cpumask_lookup_table[MAX_NUMNODES];
41 
42 struct pglist_data *node_data[MAX_NUMNODES];
43 bootmem_data_t __initdata plat_node_bdata[MAX_NUMNODES];
44 static int min_common_depth;
45 
46 /*
47  * We need somewhere to store start/span for each node until we have
48  * allocated the real node_data structures.
49  */
50 static struct {
51 	unsigned long node_start_pfn;
52 	unsigned long node_end_pfn;
53 	unsigned long node_present_pages;
54 } init_node_data[MAX_NUMNODES] __initdata;
55 
56 EXPORT_SYMBOL(node_data);
57 EXPORT_SYMBOL(numa_cpu_lookup_table);
58 EXPORT_SYMBOL(numa_memory_lookup_table);
59 EXPORT_SYMBOL(numa_cpumask_lookup_table);
60 
61 static inline void map_cpu_to_node(int cpu, int node)
62 {
63 	numa_cpu_lookup_table[cpu] = node;
64 	if (!(cpu_isset(cpu, numa_cpumask_lookup_table[node]))) {
65 		cpu_set(cpu, numa_cpumask_lookup_table[node]);
66 	}
67 }
68 
69 #ifdef CONFIG_HOTPLUG_CPU
70 static void unmap_cpu_from_node(unsigned long cpu)
71 {
72 	int node = numa_cpu_lookup_table[cpu];
73 
74 	dbg("removing cpu %lu from node %d\n", cpu, node);
75 
76 	if (cpu_isset(cpu, numa_cpumask_lookup_table[node])) {
77 		cpu_clear(cpu, numa_cpumask_lookup_table[node]);
78 	} else {
79 		printk(KERN_ERR "WARNING: cpu %lu not found in node %d\n",
80 		       cpu, node);
81 	}
82 }
83 #endif /* CONFIG_HOTPLUG_CPU */
84 
85 static struct device_node * __devinit find_cpu_node(unsigned int cpu)
86 {
87 	unsigned int hw_cpuid = get_hard_smp_processor_id(cpu);
88 	struct device_node *cpu_node = NULL;
89 	unsigned int *interrupt_server, *reg;
90 	int len;
91 
92 	while ((cpu_node = of_find_node_by_type(cpu_node, "cpu")) != NULL) {
93 		/* Try interrupt server first */
94 		interrupt_server = (unsigned int *)get_property(cpu_node,
95 					"ibm,ppc-interrupt-server#s", &len);
96 
97 		len = len / sizeof(u32);
98 
99 		if (interrupt_server && (len > 0)) {
100 			while (len--) {
101 				if (interrupt_server[len] == hw_cpuid)
102 					return cpu_node;
103 			}
104 		} else {
105 			reg = (unsigned int *)get_property(cpu_node,
106 							   "reg", &len);
107 			if (reg && (len > 0) && (reg[0] == hw_cpuid))
108 				return cpu_node;
109 		}
110 	}
111 
112 	return NULL;
113 }
114 
115 /* must hold reference to node during call */
116 static int *of_get_associativity(struct device_node *dev)
117 {
118 	return (unsigned int *)get_property(dev, "ibm,associativity", NULL);
119 }
120 
121 static int of_node_numa_domain(struct device_node *device)
122 {
123 	int numa_domain;
124 	unsigned int *tmp;
125 
126 	if (min_common_depth == -1)
127 		return 0;
128 
129 	tmp = of_get_associativity(device);
130 	if (tmp && (tmp[0] >= min_common_depth)) {
131 		numa_domain = tmp[min_common_depth];
132 	} else {
133 		dbg("WARNING: no NUMA information for %s\n",
134 		    device->full_name);
135 		numa_domain = 0;
136 	}
137 	return numa_domain;
138 }
139 
140 /*
141  * In theory, the "ibm,associativity" property may contain multiple
142  * associativity lists because a resource may be multiply connected
143  * into the machine.  This resource then has different associativity
144  * characteristics relative to its multiple connections.  We ignore
145  * this for now.  We also assume that all cpu and memory sets have
146  * their distances represented at a common level.  This won't be
147  * true for heirarchical NUMA.
148  *
149  * In any case the ibm,associativity-reference-points should give
150  * the correct depth for a normal NUMA system.
151  *
152  * - Dave Hansen <haveblue@us.ibm.com>
153  */
154 static int __init find_min_common_depth(void)
155 {
156 	int depth;
157 	unsigned int *ref_points;
158 	struct device_node *rtas_root;
159 	unsigned int len;
160 
161 	rtas_root = of_find_node_by_path("/rtas");
162 
163 	if (!rtas_root)
164 		return -1;
165 
166 	/*
167 	 * this property is 2 32-bit integers, each representing a level of
168 	 * depth in the associativity nodes.  The first is for an SMP
169 	 * configuration (should be all 0's) and the second is for a normal
170 	 * NUMA configuration.
171 	 */
172 	ref_points = (unsigned int *)get_property(rtas_root,
173 			"ibm,associativity-reference-points", &len);
174 
175 	if ((len >= 1) && ref_points) {
176 		depth = ref_points[1];
177 	} else {
178 		dbg("WARNING: could not find NUMA "
179 		    "associativity reference point\n");
180 		depth = -1;
181 	}
182 	of_node_put(rtas_root);
183 
184 	return depth;
185 }
186 
187 static int __init get_mem_addr_cells(void)
188 {
189 	struct device_node *memory = NULL;
190 	int rc;
191 
192 	memory = of_find_node_by_type(memory, "memory");
193 	if (!memory)
194 		return 0; /* it won't matter */
195 
196 	rc = prom_n_addr_cells(memory);
197 	return rc;
198 }
199 
200 static int __init get_mem_size_cells(void)
201 {
202 	struct device_node *memory = NULL;
203 	int rc;
204 
205 	memory = of_find_node_by_type(memory, "memory");
206 	if (!memory)
207 		return 0; /* it won't matter */
208 	rc = prom_n_size_cells(memory);
209 	return rc;
210 }
211 
212 static unsigned long read_n_cells(int n, unsigned int **buf)
213 {
214 	unsigned long result = 0;
215 
216 	while (n--) {
217 		result = (result << 32) | **buf;
218 		(*buf)++;
219 	}
220 	return result;
221 }
222 
223 /*
224  * Figure out to which domain a cpu belongs and stick it there.
225  * Return the id of the domain used.
226  */
227 static int numa_setup_cpu(unsigned long lcpu)
228 {
229 	int numa_domain = 0;
230 	struct device_node *cpu = find_cpu_node(lcpu);
231 
232 	if (!cpu) {
233 		WARN_ON(1);
234 		goto out;
235 	}
236 
237 	numa_domain = of_node_numa_domain(cpu);
238 
239 	if (numa_domain >= num_online_nodes()) {
240 		/*
241 		 * POWER4 LPAR uses 0xffff as invalid node,
242 		 * dont warn in this case.
243 		 */
244 		if (numa_domain != 0xffff)
245 			printk(KERN_ERR "WARNING: cpu %ld "
246 			       "maps to invalid NUMA node %d\n",
247 			       lcpu, numa_domain);
248 		numa_domain = 0;
249 	}
250 out:
251 	node_set_online(numa_domain);
252 
253 	map_cpu_to_node(lcpu, numa_domain);
254 
255 	of_node_put(cpu);
256 
257 	return numa_domain;
258 }
259 
260 static int cpu_numa_callback(struct notifier_block *nfb,
261 			     unsigned long action,
262 			     void *hcpu)
263 {
264 	unsigned long lcpu = (unsigned long)hcpu;
265 	int ret = NOTIFY_DONE;
266 
267 	switch (action) {
268 	case CPU_UP_PREPARE:
269 		if (min_common_depth == -1 || !numa_enabled)
270 			map_cpu_to_node(lcpu, 0);
271 		else
272 			numa_setup_cpu(lcpu);
273 		ret = NOTIFY_OK;
274 		break;
275 #ifdef CONFIG_HOTPLUG_CPU
276 	case CPU_DEAD:
277 	case CPU_UP_CANCELED:
278 		unmap_cpu_from_node(lcpu);
279 		break;
280 		ret = NOTIFY_OK;
281 #endif
282 	}
283 	return ret;
284 }
285 
286 /*
287  * Check and possibly modify a memory region to enforce the memory limit.
288  *
289  * Returns the size the region should have to enforce the memory limit.
290  * This will either be the original value of size, a truncated value,
291  * or zero. If the returned value of size is 0 the region should be
292  * discarded as it lies wholy above the memory limit.
293  */
294 static unsigned long __init numa_enforce_memory_limit(unsigned long start, unsigned long size)
295 {
296 	/*
297 	 * We use lmb_end_of_DRAM() in here instead of memory_limit because
298 	 * we've already adjusted it for the limit and it takes care of
299 	 * having memory holes below the limit.
300 	 */
301 
302 	if (! memory_limit)
303 		return size;
304 
305 	if (start + size <= lmb_end_of_DRAM())
306 		return size;
307 
308 	if (start >= lmb_end_of_DRAM())
309 		return 0;
310 
311 	return lmb_end_of_DRAM() - start;
312 }
313 
314 static int __init parse_numa_properties(void)
315 {
316 	struct device_node *cpu = NULL;
317 	struct device_node *memory = NULL;
318 	int addr_cells, size_cells;
319 	int max_domain = 0;
320 	long entries = lmb_end_of_DRAM() >> MEMORY_INCREMENT_SHIFT;
321 	unsigned long i;
322 
323 	if (numa_enabled == 0) {
324 		printk(KERN_WARNING "NUMA disabled by user\n");
325 		return -1;
326 	}
327 
328 	numa_memory_lookup_table =
329 		(char *)abs_to_virt(lmb_alloc(entries * sizeof(char), 1));
330 	memset(numa_memory_lookup_table, 0, entries * sizeof(char));
331 
332 	for (i = 0; i < entries ; i++)
333 		numa_memory_lookup_table[i] = ARRAY_INITIALISER;
334 
335 	min_common_depth = find_min_common_depth();
336 
337 	dbg("NUMA associativity depth for CPU/Memory: %d\n", min_common_depth);
338 	if (min_common_depth < 0)
339 		return min_common_depth;
340 
341 	max_domain = numa_setup_cpu(boot_cpuid);
342 
343 	/*
344 	 * Even though we connect cpus to numa domains later in SMP init,
345 	 * we need to know the maximum node id now. This is because each
346 	 * node id must have NODE_DATA etc backing it.
347 	 * As a result of hotplug we could still have cpus appear later on
348 	 * with larger node ids. In that case we force the cpu into node 0.
349 	 */
350 	for_each_cpu(i) {
351 		int numa_domain;
352 
353 		cpu = find_cpu_node(i);
354 
355 		if (cpu) {
356 			numa_domain = of_node_numa_domain(cpu);
357 			of_node_put(cpu);
358 
359 			if (numa_domain < MAX_NUMNODES &&
360 			    max_domain < numa_domain)
361 				max_domain = numa_domain;
362 		}
363 	}
364 
365 	addr_cells = get_mem_addr_cells();
366 	size_cells = get_mem_size_cells();
367 	memory = NULL;
368 	while ((memory = of_find_node_by_type(memory, "memory")) != NULL) {
369 		unsigned long start;
370 		unsigned long size;
371 		int numa_domain;
372 		int ranges;
373 		unsigned int *memcell_buf;
374 		unsigned int len;
375 
376 		memcell_buf = (unsigned int *)get_property(memory, "reg", &len);
377 		if (!memcell_buf || len <= 0)
378 			continue;
379 
380 		ranges = memory->n_addrs;
381 new_range:
382 		/* these are order-sensitive, and modify the buffer pointer */
383 		start = read_n_cells(addr_cells, &memcell_buf);
384 		size = read_n_cells(size_cells, &memcell_buf);
385 
386 		start = _ALIGN_DOWN(start, MEMORY_INCREMENT);
387 		size = _ALIGN_UP(size, MEMORY_INCREMENT);
388 
389 		numa_domain = of_node_numa_domain(memory);
390 
391 		if (numa_domain >= MAX_NUMNODES) {
392 			if (numa_domain != 0xffff)
393 				printk(KERN_ERR "WARNING: memory at %lx maps "
394 				       "to invalid NUMA node %d\n", start,
395 				       numa_domain);
396 			numa_domain = 0;
397 		}
398 
399 		if (max_domain < numa_domain)
400 			max_domain = numa_domain;
401 
402 		if (! (size = numa_enforce_memory_limit(start, size))) {
403 			if (--ranges)
404 				goto new_range;
405 			else
406 				continue;
407 		}
408 
409 		/*
410 		 * Initialize new node struct, or add to an existing one.
411 		 */
412 		if (init_node_data[numa_domain].node_end_pfn) {
413 			if ((start / PAGE_SIZE) <
414 			    init_node_data[numa_domain].node_start_pfn)
415 				init_node_data[numa_domain].node_start_pfn =
416 					start / PAGE_SIZE;
417 			if (((start / PAGE_SIZE) + (size / PAGE_SIZE)) >
418 			    init_node_data[numa_domain].node_end_pfn)
419 				init_node_data[numa_domain].node_end_pfn =
420 					(start / PAGE_SIZE) +
421 					(size / PAGE_SIZE);
422 
423 			init_node_data[numa_domain].node_present_pages +=
424 				size / PAGE_SIZE;
425 		} else {
426 			node_set_online(numa_domain);
427 
428 			init_node_data[numa_domain].node_start_pfn =
429 				start / PAGE_SIZE;
430 			init_node_data[numa_domain].node_end_pfn =
431 				init_node_data[numa_domain].node_start_pfn +
432 				size / PAGE_SIZE;
433 			init_node_data[numa_domain].node_present_pages =
434 				size / PAGE_SIZE;
435 		}
436 
437 		for (i = start ; i < (start+size); i += MEMORY_INCREMENT)
438 			numa_memory_lookup_table[i >> MEMORY_INCREMENT_SHIFT] =
439 				numa_domain;
440 
441 		if (--ranges)
442 			goto new_range;
443 	}
444 
445 	for (i = 0; i <= max_domain; i++)
446 		node_set_online(i);
447 
448 	return 0;
449 }
450 
451 static void __init setup_nonnuma(void)
452 {
453 	unsigned long top_of_ram = lmb_end_of_DRAM();
454 	unsigned long total_ram = lmb_phys_mem_size();
455 	unsigned long i;
456 
457 	printk(KERN_INFO "Top of RAM: 0x%lx, Total RAM: 0x%lx\n",
458 	       top_of_ram, total_ram);
459 	printk(KERN_INFO "Memory hole size: %ldMB\n",
460 	       (top_of_ram - total_ram) >> 20);
461 
462 	if (!numa_memory_lookup_table) {
463 		long entries = top_of_ram >> MEMORY_INCREMENT_SHIFT;
464 		numa_memory_lookup_table =
465 			(char *)abs_to_virt(lmb_alloc(entries * sizeof(char), 1));
466 		memset(numa_memory_lookup_table, 0, entries * sizeof(char));
467 		for (i = 0; i < entries ; i++)
468 			numa_memory_lookup_table[i] = ARRAY_INITIALISER;
469 	}
470 
471 	map_cpu_to_node(boot_cpuid, 0);
472 
473 	node_set_online(0);
474 
475 	init_node_data[0].node_start_pfn = 0;
476 	init_node_data[0].node_end_pfn = lmb_end_of_DRAM() / PAGE_SIZE;
477 	init_node_data[0].node_present_pages = total_ram / PAGE_SIZE;
478 
479 	for (i = 0 ; i < top_of_ram; i += MEMORY_INCREMENT)
480 		numa_memory_lookup_table[i >> MEMORY_INCREMENT_SHIFT] = 0;
481 }
482 
483 static void __init dump_numa_topology(void)
484 {
485 	unsigned int node;
486 	unsigned int count;
487 
488 	if (min_common_depth == -1 || !numa_enabled)
489 		return;
490 
491 	for_each_online_node(node) {
492 		unsigned long i;
493 
494 		printk(KERN_INFO "Node %d Memory:", node);
495 
496 		count = 0;
497 
498 		for (i = 0; i < lmb_end_of_DRAM(); i += MEMORY_INCREMENT) {
499 			if (numa_memory_lookup_table[i >> MEMORY_INCREMENT_SHIFT] == node) {
500 				if (count == 0)
501 					printk(" 0x%lx", i);
502 				++count;
503 			} else {
504 				if (count > 0)
505 					printk("-0x%lx", i);
506 				count = 0;
507 			}
508 		}
509 
510 		if (count > 0)
511 			printk("-0x%lx", i);
512 		printk("\n");
513 	}
514 	return;
515 }
516 
517 /*
518  * Allocate some memory, satisfying the lmb or bootmem allocator where
519  * required. nid is the preferred node and end is the physical address of
520  * the highest address in the node.
521  *
522  * Returns the physical address of the memory.
523  */
524 static unsigned long careful_allocation(int nid, unsigned long size,
525 					unsigned long align, unsigned long end)
526 {
527 	unsigned long ret = lmb_alloc_base(size, align, end);
528 
529 	/* retry over all memory */
530 	if (!ret)
531 		ret = lmb_alloc_base(size, align, lmb_end_of_DRAM());
532 
533 	if (!ret)
534 		panic("numa.c: cannot allocate %lu bytes on node %d",
535 		      size, nid);
536 
537 	/*
538 	 * If the memory came from a previously allocated node, we must
539 	 * retry with the bootmem allocator.
540 	 */
541 	if (pa_to_nid(ret) < nid) {
542 		nid = pa_to_nid(ret);
543 		ret = (unsigned long)__alloc_bootmem_node(NODE_DATA(nid),
544 				size, align, 0);
545 
546 		if (!ret)
547 			panic("numa.c: cannot allocate %lu bytes on node %d",
548 			      size, nid);
549 
550 		ret = virt_to_abs(ret);
551 
552 		dbg("alloc_bootmem %lx %lx\n", ret, size);
553 	}
554 
555 	return ret;
556 }
557 
558 void __init do_init_bootmem(void)
559 {
560 	int nid;
561 	int addr_cells, size_cells;
562 	struct device_node *memory = NULL;
563 	static struct notifier_block ppc64_numa_nb = {
564 		.notifier_call = cpu_numa_callback,
565 		.priority = 1 /* Must run before sched domains notifier. */
566 	};
567 
568 	min_low_pfn = 0;
569 	max_low_pfn = lmb_end_of_DRAM() >> PAGE_SHIFT;
570 	max_pfn = max_low_pfn;
571 
572 	if (parse_numa_properties())
573 		setup_nonnuma();
574 	else
575 		dump_numa_topology();
576 
577 	register_cpu_notifier(&ppc64_numa_nb);
578 
579 	for_each_online_node(nid) {
580 		unsigned long start_paddr, end_paddr;
581 		int i;
582 		unsigned long bootmem_paddr;
583 		unsigned long bootmap_pages;
584 
585 		start_paddr = init_node_data[nid].node_start_pfn * PAGE_SIZE;
586 		end_paddr = init_node_data[nid].node_end_pfn * PAGE_SIZE;
587 
588 		/* Allocate the node structure node local if possible */
589 		NODE_DATA(nid) = (struct pglist_data *)careful_allocation(nid,
590 					sizeof(struct pglist_data),
591 					SMP_CACHE_BYTES, end_paddr);
592 		NODE_DATA(nid) = abs_to_virt(NODE_DATA(nid));
593 		memset(NODE_DATA(nid), 0, sizeof(struct pglist_data));
594 
595   		dbg("node %d\n", nid);
596 		dbg("NODE_DATA() = %p\n", NODE_DATA(nid));
597 
598 		NODE_DATA(nid)->bdata = &plat_node_bdata[nid];
599 		NODE_DATA(nid)->node_start_pfn =
600 			init_node_data[nid].node_start_pfn;
601 		NODE_DATA(nid)->node_spanned_pages =
602 			end_paddr - start_paddr;
603 
604 		if (NODE_DATA(nid)->node_spanned_pages == 0)
605   			continue;
606 
607   		dbg("start_paddr = %lx\n", start_paddr);
608   		dbg("end_paddr = %lx\n", end_paddr);
609 
610 		bootmap_pages = bootmem_bootmap_pages((end_paddr - start_paddr) >> PAGE_SHIFT);
611 
612 		bootmem_paddr = careful_allocation(nid,
613 				bootmap_pages << PAGE_SHIFT,
614 				PAGE_SIZE, end_paddr);
615 		memset(abs_to_virt(bootmem_paddr), 0,
616 		       bootmap_pages << PAGE_SHIFT);
617 		dbg("bootmap_paddr = %lx\n", bootmem_paddr);
618 
619 		init_bootmem_node(NODE_DATA(nid), bootmem_paddr >> PAGE_SHIFT,
620 				  start_paddr >> PAGE_SHIFT,
621 				  end_paddr >> PAGE_SHIFT);
622 
623 		/*
624 		 * We need to do another scan of all memory sections to
625 		 * associate memory with the correct node.
626 		 */
627 		addr_cells = get_mem_addr_cells();
628 		size_cells = get_mem_size_cells();
629 		memory = NULL;
630 		while ((memory = of_find_node_by_type(memory, "memory")) != NULL) {
631 			unsigned long mem_start, mem_size;
632 			int numa_domain, ranges;
633 			unsigned int *memcell_buf;
634 			unsigned int len;
635 
636 			memcell_buf = (unsigned int *)get_property(memory, "reg", &len);
637 			if (!memcell_buf || len <= 0)
638 				continue;
639 
640 			ranges = memory->n_addrs;	/* ranges in cell */
641 new_range:
642 			mem_start = read_n_cells(addr_cells, &memcell_buf);
643 			mem_size = read_n_cells(size_cells, &memcell_buf);
644 			if (numa_enabled) {
645 				numa_domain = of_node_numa_domain(memory);
646 				if (numa_domain  >= MAX_NUMNODES)
647 					numa_domain = 0;
648 			} else
649 				numa_domain =  0;
650 
651 			if (numa_domain != nid)
652 				continue;
653 
654 			mem_size = numa_enforce_memory_limit(mem_start, mem_size);
655   			if (mem_size) {
656   				dbg("free_bootmem %lx %lx\n", mem_start, mem_size);
657   				free_bootmem_node(NODE_DATA(nid), mem_start, mem_size);
658 			}
659 
660 			if (--ranges)		/* process all ranges in cell */
661 				goto new_range;
662 		}
663 
664 		/*
665 		 * Mark reserved regions on this node
666 		 */
667 		for (i = 0; i < lmb.reserved.cnt; i++) {
668 			unsigned long physbase = lmb.reserved.region[i].base;
669 			unsigned long size = lmb.reserved.region[i].size;
670 
671 			if (pa_to_nid(physbase) != nid &&
672 			    pa_to_nid(physbase+size-1) != nid)
673 				continue;
674 
675 			if (physbase < end_paddr &&
676 			    (physbase+size) > start_paddr) {
677 				/* overlaps */
678 				if (physbase < start_paddr) {
679 					size -= start_paddr - physbase;
680 					physbase = start_paddr;
681 				}
682 
683 				if (size > end_paddr - physbase)
684 					size = end_paddr - physbase;
685 
686 				dbg("reserve_bootmem %lx %lx\n", physbase,
687 				    size);
688 				reserve_bootmem_node(NODE_DATA(nid), physbase,
689 						     size);
690 			}
691 		}
692 		/*
693 		 * This loop may look famaliar, but we have to do it again
694 		 * after marking our reserved memory to mark memory present
695 		 * for sparsemem.
696 		 */
697 		addr_cells = get_mem_addr_cells();
698 		size_cells = get_mem_size_cells();
699 		memory = NULL;
700 		while ((memory = of_find_node_by_type(memory, "memory")) != NULL) {
701 			unsigned long mem_start, mem_size;
702 			int numa_domain, ranges;
703 			unsigned int *memcell_buf;
704 			unsigned int len;
705 
706 			memcell_buf = (unsigned int *)get_property(memory, "reg", &len);
707 			if (!memcell_buf || len <= 0)
708 				continue;
709 
710 			ranges = memory->n_addrs;	/* ranges in cell */
711 new_range2:
712 			mem_start = read_n_cells(addr_cells, &memcell_buf);
713 			mem_size = read_n_cells(size_cells, &memcell_buf);
714 			if (numa_enabled) {
715 				numa_domain = of_node_numa_domain(memory);
716 				if (numa_domain  >= MAX_NUMNODES)
717 					numa_domain = 0;
718 			} else
719 				numa_domain =  0;
720 
721 			if (numa_domain != nid)
722 				continue;
723 
724 			mem_size = numa_enforce_memory_limit(mem_start, mem_size);
725 			memory_present(numa_domain, mem_start >> PAGE_SHIFT,
726 				       (mem_start + mem_size) >> PAGE_SHIFT);
727 
728 			if (--ranges)		/* process all ranges in cell */
729 				goto new_range2;
730 		}
731 
732 	}
733 }
734 
735 void __init paging_init(void)
736 {
737 	unsigned long zones_size[MAX_NR_ZONES];
738 	unsigned long zholes_size[MAX_NR_ZONES];
739 	int nid;
740 
741 	memset(zones_size, 0, sizeof(zones_size));
742 	memset(zholes_size, 0, sizeof(zholes_size));
743 
744 	for_each_online_node(nid) {
745 		unsigned long start_pfn;
746 		unsigned long end_pfn;
747 
748 		start_pfn = init_node_data[nid].node_start_pfn;
749 		end_pfn = init_node_data[nid].node_end_pfn;
750 
751 		zones_size[ZONE_DMA] = end_pfn - start_pfn;
752 		zholes_size[ZONE_DMA] = zones_size[ZONE_DMA] -
753 			init_node_data[nid].node_present_pages;
754 
755 		dbg("free_area_init node %d %lx %lx (hole: %lx)\n", nid,
756 		    zones_size[ZONE_DMA], start_pfn, zholes_size[ZONE_DMA]);
757 
758 		free_area_init_node(nid, NODE_DATA(nid), zones_size,
759 							start_pfn, zholes_size);
760 	}
761 }
762 
763 static int __init early_numa(char *p)
764 {
765 	if (!p)
766 		return 0;
767 
768 	if (strstr(p, "off"))
769 		numa_enabled = 0;
770 
771 	if (strstr(p, "debug"))
772 		numa_debug = 1;
773 
774 	return 0;
775 }
776 early_param("numa", early_numa);
777