80444c5c9b148d67f34c49f59efc4574133f4b5e
[sfrench/cifs-2.6.git] / arch / x86 / kernel / e820_32.c
1 #include <linux/kernel.h>
2 #include <linux/types.h>
3 #include <linux/init.h>
4 #include <linux/bootmem.h>
5 #include <linux/ioport.h>
6 #include <linux/string.h>
7 #include <linux/kexec.h>
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/pfn.h>
11 #include <linux/uaccess.h>
12 #include <linux/suspend.h>
13
14 #include <asm/pgtable.h>
15 #include <asm/page.h>
16 #include <asm/e820.h>
17 #include <asm/setup.h>
18
19 struct e820map e820;
20 struct change_member {
21         struct e820entry *pbios; /* pointer to original bios entry */
22         unsigned long long addr; /* address for this change point */
23 };
24 static struct change_member change_point_list[2*E820MAX] __initdata;
25 static struct change_member *change_point[2*E820MAX] __initdata;
26 static struct e820entry *overlap_list[E820MAX] __initdata;
27 static struct e820entry new_bios[E820MAX] __initdata;
28 /* For PCI or other memory-mapped resources */
29 unsigned long pci_mem_start = 0x10000000;
30 #ifdef CONFIG_PCI
31 EXPORT_SYMBOL(pci_mem_start);
32 #endif
33 extern int user_defined_memmap;
34
35 static struct resource system_rom_resource = {
36         .name   = "System ROM",
37         .start  = 0xf0000,
38         .end    = 0xfffff,
39         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
40 };
41
42 static struct resource extension_rom_resource = {
43         .name   = "Extension ROM",
44         .start  = 0xe0000,
45         .end    = 0xeffff,
46         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
47 };
48
49 static struct resource adapter_rom_resources[] = { {
50         .name   = "Adapter ROM",
51         .start  = 0xc8000,
52         .end    = 0,
53         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
54 }, {
55         .name   = "Adapter ROM",
56         .start  = 0,
57         .end    = 0,
58         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
59 }, {
60         .name   = "Adapter ROM",
61         .start  = 0,
62         .end    = 0,
63         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
64 }, {
65         .name   = "Adapter ROM",
66         .start  = 0,
67         .end    = 0,
68         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
69 }, {
70         .name   = "Adapter ROM",
71         .start  = 0,
72         .end    = 0,
73         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
74 }, {
75         .name   = "Adapter ROM",
76         .start  = 0,
77         .end    = 0,
78         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
79 } };
80
81 static struct resource video_rom_resource = {
82         .name   = "Video ROM",
83         .start  = 0xc0000,
84         .end    = 0xc7fff,
85         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
86 };
87
88 #define ROMSIGNATURE 0xaa55
89
90 static int __init romsignature(const unsigned char *rom)
91 {
92         const unsigned short * const ptr = (const unsigned short *)rom;
93         unsigned short sig;
94
95         return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
96 }
97
98 static int __init romchecksum(const unsigned char *rom, unsigned long length)
99 {
100         unsigned char sum, c;
101
102         for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
103                 sum += c;
104         return !length && !sum;
105 }
106
107 static void __init probe_roms(void)
108 {
109         const unsigned char *rom;
110         unsigned long start, length, upper;
111         unsigned char c;
112         int i;
113
114         /* video rom */
115         upper = adapter_rom_resources[0].start;
116         for (start = video_rom_resource.start; start < upper; start += 2048) {
117                 rom = isa_bus_to_virt(start);
118                 if (!romsignature(rom))
119                         continue;
120
121                 video_rom_resource.start = start;
122
123                 if (probe_kernel_address(rom + 2, c) != 0)
124                         continue;
125
126                 /* 0 < length <= 0x7f * 512, historically */
127                 length = c * 512;
128
129                 /* if checksum okay, trust length byte */
130                 if (length && romchecksum(rom, length))
131                         video_rom_resource.end = start + length - 1;
132
133                 request_resource(&iomem_resource, &video_rom_resource);
134                 break;
135         }
136
137         start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
138         if (start < upper)
139                 start = upper;
140
141         /* system rom */
142         request_resource(&iomem_resource, &system_rom_resource);
143         upper = system_rom_resource.start;
144
145         /* check for extension rom (ignore length byte!) */
146         rom = isa_bus_to_virt(extension_rom_resource.start);
147         if (romsignature(rom)) {
148                 length = extension_rom_resource.end - extension_rom_resource.start + 1;
149                 if (romchecksum(rom, length)) {
150                         request_resource(&iomem_resource, &extension_rom_resource);
151                         upper = extension_rom_resource.start;
152                 }
153         }
154
155         /* check for adapter roms on 2k boundaries */
156         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
157                 rom = isa_bus_to_virt(start);
158                 if (!romsignature(rom))
159                         continue;
160
161                 if (probe_kernel_address(rom + 2, c) != 0)
162                         continue;
163
164                 /* 0 < length <= 0x7f * 512, historically */
165                 length = c * 512;
166
167                 /* but accept any length that fits if checksum okay */
168                 if (!length || start + length > upper || !romchecksum(rom, length))
169                         continue;
170
171                 adapter_rom_resources[i].start = start;
172                 adapter_rom_resources[i].end = start + length - 1;
173                 request_resource(&iomem_resource, &adapter_rom_resources[i]);
174
175                 start = adapter_rom_resources[i++].end & ~2047UL;
176         }
177 }
178
179 /*
180  * Request address space for all standard RAM and ROM resources
181  * and also for regions reported as reserved by the e820.
182  */
183 void __init init_iomem_resources(struct resource *code_resource,
184                 struct resource *data_resource,
185                 struct resource *bss_resource)
186 {
187         int i;
188
189         probe_roms();
190         for (i = 0; i < e820.nr_map; i++) {
191                 struct resource *res;
192 #ifndef CONFIG_RESOURCES_64BIT
193                 if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
194                         continue;
195 #endif
196                 res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
197                 switch (e820.map[i].type) {
198                 case E820_RAM:  res->name = "System RAM"; break;
199                 case E820_ACPI: res->name = "ACPI Tables"; break;
200                 case E820_NVS:  res->name = "ACPI Non-volatile Storage"; break;
201                 default:        res->name = "reserved";
202                 }
203                 res->start = e820.map[i].addr;
204                 res->end = res->start + e820.map[i].size - 1;
205                 res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
206                 if (request_resource(&iomem_resource, res)) {
207                         kfree(res);
208                         continue;
209                 }
210                 if (e820.map[i].type == E820_RAM) {
211                         /*
212                          *  We don't know which RAM region contains kernel data,
213                          *  so we try it repeatedly and let the resource manager
214                          *  test it.
215                          */
216                         request_resource(res, code_resource);
217                         request_resource(res, data_resource);
218                         request_resource(res, bss_resource);
219 #ifdef CONFIG_KEXEC
220                         if (crashk_res.start != crashk_res.end)
221                                 request_resource(res, &crashk_res);
222 #endif
223                 }
224         }
225 }
226
227 #if defined(CONFIG_PM) && defined(CONFIG_HIBERNATION)
228 /**
229  * e820_mark_nosave_regions - Find the ranges of physical addresses that do not
230  * correspond to e820 RAM areas and mark the corresponding pages as nosave for
231  * hibernation.
232  *
233  * This function requires the e820 map to be sorted and without any
234  * overlapping entries and assumes the first e820 area to be RAM.
235  */
236 void __init e820_mark_nosave_regions(void)
237 {
238         int i;
239         unsigned long pfn;
240
241         pfn = PFN_DOWN(e820.map[0].addr + e820.map[0].size);
242         for (i = 1; i < e820.nr_map; i++) {
243                 struct e820entry *ei = &e820.map[i];
244
245                 if (pfn < PFN_UP(ei->addr))
246                         register_nosave_region(pfn, PFN_UP(ei->addr));
247
248                 pfn = PFN_DOWN(ei->addr + ei->size);
249                 if (ei->type != E820_RAM)
250                         register_nosave_region(PFN_UP(ei->addr), pfn);
251
252                 if (pfn >= max_low_pfn)
253                         break;
254         }
255 }
256 #endif
257
258 void __init add_memory_region(unsigned long long start,
259                               unsigned long long size, int type)
260 {
261         int x;
262
263         x = e820.nr_map;
264
265         if (x == E820MAX) {
266                 printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
267                 return;
268         }
269
270         e820.map[x].addr = start;
271         e820.map[x].size = size;
272         e820.map[x].type = type;
273         e820.nr_map++;
274 } /* add_memory_region */
275
276 /*
277  * Sanitize the BIOS e820 map.
278  *
279  * Some e820 responses include overlapping entries.  The following
280  * replaces the original e820 map with a new one, removing overlaps.
281  *
282  */
283 int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
284 {
285         struct change_member *change_tmp;
286         unsigned long current_type, last_type;
287         unsigned long long last_addr;
288         int chgidx, still_changing;
289         int overlap_entries;
290         int new_bios_entry;
291         int old_nr, new_nr, chg_nr;
292         int i;
293
294         /*
295                 Visually we're performing the following (1,2,3,4 = memory types)...
296
297                 Sample memory map (w/overlaps):
298                    ____22__________________
299                    ______________________4_
300                    ____1111________________
301                    _44_____________________
302                    11111111________________
303                    ____________________33__
304                    ___________44___________
305                    __________33333_________
306                    ______________22________
307                    ___________________2222_
308                    _________111111111______
309                    _____________________11_
310                    _________________4______
311
312                 Sanitized equivalent (no overlap):
313                    1_______________________
314                    _44_____________________
315                    ___1____________________
316                    ____22__________________
317                    ______11________________
318                    _________1______________
319                    __________3_____________
320                    ___________44___________
321                    _____________33_________
322                    _______________2________
323                    ________________1_______
324                    _________________4______
325                    ___________________2____
326                    ____________________33__
327                    ______________________4_
328         */
329         /* if there's only one memory region, don't bother */
330         if (*pnr_map < 2) {
331                 return -1;
332         }
333
334         old_nr = *pnr_map;
335
336         /* bail out if we find any unreasonable addresses in bios map */
337         for (i=0; i<old_nr; i++)
338                 if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr) {
339                         return -1;
340                 }
341
342         /* create pointers for initial change-point information (for sorting) */
343         for (i=0; i < 2*old_nr; i++)
344                 change_point[i] = &change_point_list[i];
345
346         /* record all known change-points (starting and ending addresses),
347            omitting those that are for empty memory regions */
348         chgidx = 0;
349         for (i=0; i < old_nr; i++)      {
350                 if (biosmap[i].size != 0) {
351                         change_point[chgidx]->addr = biosmap[i].addr;
352                         change_point[chgidx++]->pbios = &biosmap[i];
353                         change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
354                         change_point[chgidx++]->pbios = &biosmap[i];
355                 }
356         }
357         chg_nr = chgidx;        /* true number of change-points */
358
359         /* sort change-point list by memory addresses (low -> high) */
360         still_changing = 1;
361         while (still_changing)  {
362                 still_changing = 0;
363                 for (i=1; i < chg_nr; i++)  {
364                         /* if <current_addr> > <last_addr>, swap */
365                         /* or, if current=<start_addr> & last=<end_addr>, swap */
366                         if ((change_point[i]->addr < change_point[i-1]->addr) ||
367                                 ((change_point[i]->addr == change_point[i-1]->addr) &&
368                                  (change_point[i]->addr == change_point[i]->pbios->addr) &&
369                                  (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
370                            )
371                         {
372                                 change_tmp = change_point[i];
373                                 change_point[i] = change_point[i-1];
374                                 change_point[i-1] = change_tmp;
375                                 still_changing=1;
376                         }
377                 }
378         }
379
380         /* create a new bios memory map, removing overlaps */
381         overlap_entries=0;       /* number of entries in the overlap table */
382         new_bios_entry=0;        /* index for creating new bios map entries */
383         last_type = 0;           /* start with undefined memory type */
384         last_addr = 0;           /* start with 0 as last starting address */
385         /* loop through change-points, determining affect on the new bios map */
386         for (chgidx=0; chgidx < chg_nr; chgidx++)
387         {
388                 /* keep track of all overlapping bios entries */
389                 if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
390                 {
391                         /* add map entry to overlap list (> 1 entry implies an overlap) */
392                         overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
393                 }
394                 else
395                 {
396                         /* remove entry from list (order independent, so swap with last) */
397                         for (i=0; i<overlap_entries; i++)
398                         {
399                                 if (overlap_list[i] == change_point[chgidx]->pbios)
400                                         overlap_list[i] = overlap_list[overlap_entries-1];
401                         }
402                         overlap_entries--;
403                 }
404                 /* if there are overlapping entries, decide which "type" to use */
405                 /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
406                 current_type = 0;
407                 for (i=0; i<overlap_entries; i++)
408                         if (overlap_list[i]->type > current_type)
409                                 current_type = overlap_list[i]->type;
410                 /* continue building up new bios map based on this information */
411                 if (current_type != last_type)  {
412                         if (last_type != 0)      {
413                                 new_bios[new_bios_entry].size =
414                                         change_point[chgidx]->addr - last_addr;
415                                 /* move forward only if the new size was non-zero */
416                                 if (new_bios[new_bios_entry].size != 0)
417                                         if (++new_bios_entry >= E820MAX)
418                                                 break;  /* no more space left for new bios entries */
419                         }
420                         if (current_type != 0)  {
421                                 new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
422                                 new_bios[new_bios_entry].type = current_type;
423                                 last_addr=change_point[chgidx]->addr;
424                         }
425                         last_type = current_type;
426                 }
427         }
428         new_nr = new_bios_entry;   /* retain count for new bios entries */
429
430         /* copy new bios mapping into original location */
431         memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
432         *pnr_map = new_nr;
433
434         return 0;
435 }
436
437 /*
438  * Copy the BIOS e820 map into a safe place.
439  *
440  * Sanity-check it while we're at it..
441  *
442  * If we're lucky and live on a modern system, the setup code
443  * will have given us a memory map that we can use to properly
444  * set up memory.  If we aren't, we'll fake a memory map.
445  *
446  * We check to see that the memory map contains at least 2 elements
447  * before we'll use it, because the detection code in setup.S may
448  * not be perfect and most every PC known to man has two memory
449  * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
450  * thinkpad 560x, for example, does not cooperate with the memory
451  * detection code.)
452  */
453 int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
454 {
455         /* Only one memory region (or negative)? Ignore it */
456         if (nr_map < 2)
457                 return -1;
458
459         do {
460                 unsigned long long start = biosmap->addr;
461                 unsigned long long size = biosmap->size;
462                 unsigned long long end = start + size;
463                 unsigned long type = biosmap->type;
464
465                 /* Overflow in 64 bits? Ignore the memory map. */
466                 if (start > end)
467                         return -1;
468
469                 /*
470                  * Some BIOSes claim RAM in the 640k - 1M region.
471                  * Not right. Fix it up.
472                  */
473                 if (type == E820_RAM) {
474                         if (start < 0x100000ULL && end > 0xA0000ULL) {
475                                 if (start < 0xA0000ULL)
476                                         add_memory_region(start, 0xA0000ULL-start, type);
477                                 if (end <= 0x100000ULL)
478                                         continue;
479                                 start = 0x100000ULL;
480                                 size = end - start;
481                         }
482                 }
483                 add_memory_region(start, size, type);
484         } while (biosmap++,--nr_map);
485         return 0;
486 }
487
488 /*
489  * Find the highest page frame number we have available
490  */
491 void __init find_max_pfn(void)
492 {
493         int i;
494
495         max_pfn = 0;
496
497         for (i = 0; i < e820.nr_map; i++) {
498                 unsigned long start, end;
499                 /* RAM? */
500                 if (e820.map[i].type != E820_RAM)
501                         continue;
502                 start = PFN_UP(e820.map[i].addr);
503                 end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
504                 if (start >= end)
505                         continue;
506                 if (end > max_pfn)
507                         max_pfn = end;
508                 memory_present(0, start, end);
509         }
510 }
511
512 /*
513  * Register fully available low RAM pages with the bootmem allocator.
514  */
515 void __init register_bootmem_low_pages(unsigned long max_low_pfn)
516 {
517         int i;
518
519         for (i = 0; i < e820.nr_map; i++) {
520                 unsigned long curr_pfn, last_pfn, size;
521                 /*
522                  * Reserve usable low memory
523                  */
524                 if (e820.map[i].type != E820_RAM)
525                         continue;
526                 /*
527                  * We are rounding up the start address of usable memory:
528                  */
529                 curr_pfn = PFN_UP(e820.map[i].addr);
530                 if (curr_pfn >= max_low_pfn)
531                         continue;
532                 /*
533                  * ... and at the end of the usable range downwards:
534                  */
535                 last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
536
537                 if (last_pfn > max_low_pfn)
538                         last_pfn = max_low_pfn;
539
540                 /*
541                  * .. finally, did all the rounding and playing
542                  * around just make the area go away?
543                  */
544                 if (last_pfn <= curr_pfn)
545                         continue;
546
547                 size = last_pfn - curr_pfn;
548                 free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
549         }
550 }
551
552 void __init e820_register_memory(void)
553 {
554         unsigned long gapstart, gapsize, round;
555         unsigned long long last;
556         int i;
557
558         /*
559          * Search for the biggest gap in the low 32 bits of the e820
560          * memory space.
561          */
562         last = 0x100000000ull;
563         gapstart = 0x10000000;
564         gapsize = 0x400000;
565         i = e820.nr_map;
566         while (--i >= 0) {
567                 unsigned long long start = e820.map[i].addr;
568                 unsigned long long end = start + e820.map[i].size;
569
570                 /*
571                  * Since "last" is at most 4GB, we know we'll
572                  * fit in 32 bits if this condition is true
573                  */
574                 if (last > end) {
575                         unsigned long gap = last - end;
576
577                         if (gap > gapsize) {
578                                 gapsize = gap;
579                                 gapstart = end;
580                         }
581                 }
582                 if (start < last)
583                         last = start;
584         }
585
586         /*
587          * See how much we want to round up: start off with
588          * rounding to the next 1MB area.
589          */
590         round = 0x100000;
591         while ((gapsize >> 4) > round)
592                 round += round;
593         /* Fun with two's complement */
594         pci_mem_start = (gapstart + round) & -round;
595
596         printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
597                 pci_mem_start, gapstart, gapsize);
598 }
599
600 void __init print_memory_map(char *who)
601 {
602         int i;
603
604         for (i = 0; i < e820.nr_map; i++) {
605                 printk(" %s: %016Lx - %016Lx ", who,
606                         e820.map[i].addr,
607                         e820.map[i].addr + e820.map[i].size);
608                 switch (e820.map[i].type) {
609                 case E820_RAM:  printk("(usable)\n");
610                                 break;
611                 case E820_RESERVED:
612                                 printk("(reserved)\n");
613                                 break;
614                 case E820_ACPI:
615                                 printk("(ACPI data)\n");
616                                 break;
617                 case E820_NVS:
618                                 printk("(ACPI NVS)\n");
619                                 break;
620                 default:        printk("type %u\n", e820.map[i].type);
621                                 break;
622                 }
623         }
624 }
625
626 void __init limit_regions(unsigned long long size)
627 {
628         unsigned long long current_addr;
629         int i;
630
631         print_memory_map("limit_regions start");
632         for (i = 0; i < e820.nr_map; i++) {
633                 current_addr = e820.map[i].addr + e820.map[i].size;
634                 if (current_addr < size)
635                         continue;
636
637                 if (e820.map[i].type != E820_RAM)
638                         continue;
639
640                 if (e820.map[i].addr >= size) {
641                         /*
642                          * This region starts past the end of the
643                          * requested size, skip it completely.
644                          */
645                         e820.nr_map = i;
646                 } else {
647                         e820.nr_map = i + 1;
648                         e820.map[i].size -= current_addr - size;
649                 }
650                 print_memory_map("limit_regions endfor");
651                 return;
652         }
653         print_memory_map("limit_regions endfunc");
654 }
655
656 /*
657  * This function checks if any part of the range <start,end> is mapped
658  * with type.
659  */
660 int
661 e820_any_mapped(u64 start, u64 end, unsigned type)
662 {
663         int i;
664         for (i = 0; i < e820.nr_map; i++) {
665                 const struct e820entry *ei = &e820.map[i];
666                 if (type && ei->type != type)
667                         continue;
668                 if (ei->addr >= end || ei->addr + ei->size <= start)
669                         continue;
670                 return 1;
671         }
672         return 0;
673 }
674 EXPORT_SYMBOL_GPL(e820_any_mapped);
675
676  /*
677   * This function checks if the entire range <start,end> is mapped with type.
678   *
679   * Note: this function only works correct if the e820 table is sorted and
680   * not-overlapping, which is the case
681   */
682 int __init
683 e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
684 {
685         u64 start = s;
686         u64 end = e;
687         int i;
688         for (i = 0; i < e820.nr_map; i++) {
689                 struct e820entry *ei = &e820.map[i];
690                 if (type && ei->type != type)
691                         continue;
692                 /* is the region (part) in overlap with the current region ?*/
693                 if (ei->addr >= end || ei->addr + ei->size <= start)
694                         continue;
695                 /* if the region is at the beginning of <start,end> we move
696                  * start to the end of the region since it's ok until there
697                  */
698                 if (ei->addr <= start)
699                         start = ei->addr + ei->size;
700                 /* if start is now at or beyond end, we're done, full
701                  * coverage */
702                 if (start >= end)
703                         return 1; /* we're done */
704         }
705         return 0;
706 }
707
708 static int __init parse_memmap(char *arg)
709 {
710         if (!arg)
711                 return -EINVAL;
712
713         if (strcmp(arg, "exactmap") == 0) {
714 #ifdef CONFIG_CRASH_DUMP
715                 /* If we are doing a crash dump, we
716                  * still need to know the real mem
717                  * size before original memory map is
718                  * reset.
719                  */
720                 find_max_pfn();
721                 saved_max_pfn = max_pfn;
722 #endif
723                 e820.nr_map = 0;
724                 user_defined_memmap = 1;
725         } else {
726                 /* If the user specifies memory size, we
727                  * limit the BIOS-provided memory map to
728                  * that size. exactmap can be used to specify
729                  * the exact map. mem=number can be used to
730                  * trim the existing memory map.
731                  */
732                 unsigned long long start_at, mem_size;
733
734                 mem_size = memparse(arg, &arg);
735                 if (*arg == '@') {
736                         start_at = memparse(arg+1, &arg);
737                         add_memory_region(start_at, mem_size, E820_RAM);
738                 } else if (*arg == '#') {
739                         start_at = memparse(arg+1, &arg);
740                         add_memory_region(start_at, mem_size, E820_ACPI);
741                 } else if (*arg == '$') {
742                         start_at = memparse(arg+1, &arg);
743                         add_memory_region(start_at, mem_size, E820_RESERVED);
744                 } else {
745                         limit_regions(mem_size);
746                         user_defined_memmap = 1;
747                 }
748         }
749         return 0;
750 }
751 early_param("memmap", parse_memmap);
752 void __init update_memory_range(u64 start, u64 size, unsigned old_type,
753                                 unsigned new_type)
754 {
755         int i;
756
757         BUG_ON(old_type == new_type);
758
759         for (i = 0; i < e820.nr_map; i++) {
760                 struct e820entry *ei = &e820.map[i];
761                 u64 final_start, final_end;
762                 if (ei->type != old_type)
763                         continue;
764                 /* totally covered? */
765                 if (ei->addr >= start && ei->size <= size) {
766                         ei->type = new_type;
767                         continue;
768                 }
769                 /* partially covered */
770                 final_start = max(start, ei->addr);
771                 final_end = min(start + size, ei->addr + ei->size);
772                 if (final_start >= final_end)
773                         continue;
774                 add_memory_region(final_start, final_end - final_start,
775                                          new_type);
776         }
777 }
778 void __init update_e820(void)
779 {
780         u8 nr_map;
781
782         nr_map = e820.nr_map;
783         if (sanitize_e820_map(e820.map, &nr_map))
784                 return;
785         e820.nr_map = nr_map;
786         printk(KERN_INFO "modified physical RAM map:\n");
787         print_memory_map("modified");
788 }