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>
10 #include <linux/efi.h>
11 #include <linux/pfn.h>
12 #include <linux/uaccess.h>
13 #include <linux/suspend.h>
15 #include <asm/pgtable.h>
18 #include <asm/setup.h>
22 EXPORT_SYMBOL(efi_enabled
);
26 struct change_member
{
27 struct e820entry
*pbios
; /* pointer to original bios entry */
28 unsigned long long addr
; /* address for this change point */
30 static struct change_member change_point_list
[2*E820MAX
] __initdata
;
31 static struct change_member
*change_point
[2*E820MAX
] __initdata
;
32 static struct e820entry
*overlap_list
[E820MAX
] __initdata
;
33 static struct e820entry new_bios
[E820MAX
] __initdata
;
34 /* For PCI or other memory-mapped resources */
35 unsigned long pci_mem_start
= 0x10000000;
37 EXPORT_SYMBOL(pci_mem_start
);
39 extern int user_defined_memmap
;
40 struct resource data_resource
= {
41 .name
= "Kernel data",
44 .flags
= IORESOURCE_BUSY
| IORESOURCE_MEM
47 struct resource code_resource
= {
48 .name
= "Kernel code",
51 .flags
= IORESOURCE_BUSY
| IORESOURCE_MEM
54 static struct resource system_rom_resource
= {
58 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
61 static struct resource extension_rom_resource
= {
62 .name
= "Extension ROM",
65 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
68 static struct resource adapter_rom_resources
[] = { {
69 .name
= "Adapter ROM",
72 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
74 .name
= "Adapter ROM",
77 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
79 .name
= "Adapter ROM",
82 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
84 .name
= "Adapter ROM",
87 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
89 .name
= "Adapter ROM",
92 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
94 .name
= "Adapter ROM",
97 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
100 static struct resource video_rom_resource
= {
104 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
107 static struct resource video_ram_resource
= {
108 .name
= "Video RAM area",
111 .flags
= IORESOURCE_BUSY
| IORESOURCE_MEM
114 static struct resource standard_io_resources
[] = { {
118 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
123 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
128 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
133 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
138 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
140 .name
= "dma page reg",
143 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
148 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
153 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
158 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
161 #define ROMSIGNATURE 0xaa55
163 static int __init
romsignature(const unsigned char *rom
)
165 const unsigned short * const ptr
= (const unsigned short *)rom
;
168 return probe_kernel_address(ptr
, sig
) == 0 && sig
== ROMSIGNATURE
;
171 static int __init
romchecksum(const unsigned char *rom
, unsigned long length
)
173 unsigned char sum
, c
;
175 for (sum
= 0; length
&& probe_kernel_address(rom
++, c
) == 0; length
--)
177 return !length
&& !sum
;
180 static void __init
probe_roms(void)
182 const unsigned char *rom
;
183 unsigned long start
, length
, upper
;
188 upper
= adapter_rom_resources
[0].start
;
189 for (start
= video_rom_resource
.start
; start
< upper
; start
+= 2048) {
190 rom
= isa_bus_to_virt(start
);
191 if (!romsignature(rom
))
194 video_rom_resource
.start
= start
;
196 if (probe_kernel_address(rom
+ 2, c
) != 0)
199 /* 0 < length <= 0x7f * 512, historically */
202 /* if checksum okay, trust length byte */
203 if (length
&& romchecksum(rom
, length
))
204 video_rom_resource
.end
= start
+ length
- 1;
206 request_resource(&iomem_resource
, &video_rom_resource
);
210 start
= (video_rom_resource
.end
+ 1 + 2047) & ~2047UL;
215 request_resource(&iomem_resource
, &system_rom_resource
);
216 upper
= system_rom_resource
.start
;
218 /* check for extension rom (ignore length byte!) */
219 rom
= isa_bus_to_virt(extension_rom_resource
.start
);
220 if (romsignature(rom
)) {
221 length
= extension_rom_resource
.end
- extension_rom_resource
.start
+ 1;
222 if (romchecksum(rom
, length
)) {
223 request_resource(&iomem_resource
, &extension_rom_resource
);
224 upper
= extension_rom_resource
.start
;
228 /* check for adapter roms on 2k boundaries */
229 for (i
= 0; i
< ARRAY_SIZE(adapter_rom_resources
) && start
< upper
; start
+= 2048) {
230 rom
= isa_bus_to_virt(start
);
231 if (!romsignature(rom
))
234 if (probe_kernel_address(rom
+ 2, c
) != 0)
237 /* 0 < length <= 0x7f * 512, historically */
240 /* but accept any length that fits if checksum okay */
241 if (!length
|| start
+ length
> upper
|| !romchecksum(rom
, length
))
244 adapter_rom_resources
[i
].start
= start
;
245 adapter_rom_resources
[i
].end
= start
+ length
- 1;
246 request_resource(&iomem_resource
, &adapter_rom_resources
[i
]);
248 start
= adapter_rom_resources
[i
++].end
& ~2047UL;
253 * Request address space for all standard RAM and ROM resources
254 * and also for regions reported as reserved by the e820.
257 legacy_init_iomem_resources(struct resource
*code_resource
, struct resource
*data_resource
)
262 for (i
= 0; i
< e820
.nr_map
; i
++) {
263 struct resource
*res
;
264 #ifndef CONFIG_RESOURCES_64BIT
265 if (e820
.map
[i
].addr
+ e820
.map
[i
].size
> 0x100000000ULL
)
268 res
= kzalloc(sizeof(struct resource
), GFP_ATOMIC
);
269 switch (e820
.map
[i
].type
) {
270 case E820_RAM
: res
->name
= "System RAM"; break;
271 case E820_ACPI
: res
->name
= "ACPI Tables"; break;
272 case E820_NVS
: res
->name
= "ACPI Non-volatile Storage"; break;
273 default: res
->name
= "reserved";
275 res
->start
= e820
.map
[i
].addr
;
276 res
->end
= res
->start
+ e820
.map
[i
].size
- 1;
277 res
->flags
= IORESOURCE_MEM
| IORESOURCE_BUSY
;
278 if (request_resource(&iomem_resource
, res
)) {
282 if (e820
.map
[i
].type
== E820_RAM
) {
284 * We don't know which RAM region contains kernel data,
285 * so we try it repeatedly and let the resource manager
288 request_resource(res
, code_resource
);
289 request_resource(res
, data_resource
);
291 if (crashk_res
.start
!= crashk_res
.end
)
292 request_resource(res
, &crashk_res
);
299 * Request address space for all standard resources
301 * This is called just before pcibios_init(), which is also a
302 * subsys_initcall, but is linked in later (in arch/i386/pci/common.c).
304 static int __init
request_standard_resources(void)
308 printk("Setting up standard PCI resources\n");
310 efi_initialize_iomem_resources(&code_resource
, &data_resource
);
312 legacy_init_iomem_resources(&code_resource
, &data_resource
);
314 /* EFI systems may still have VGA */
315 request_resource(&iomem_resource
, &video_ram_resource
);
317 /* request I/O space for devices used on all i[345]86 PCs */
318 for (i
= 0; i
< ARRAY_SIZE(standard_io_resources
); i
++)
319 request_resource(&ioport_resource
, &standard_io_resources
[i
]);
323 subsys_initcall(request_standard_resources
);
325 #if defined(CONFIG_PM) && defined(CONFIG_HIBERNATION)
327 * e820_mark_nosave_regions - Find the ranges of physical addresses that do not
328 * correspond to e820 RAM areas and mark the corresponding pages as nosave for
331 * This function requires the e820 map to be sorted and without any
332 * overlapping entries and assumes the first e820 area to be RAM.
334 void __init
e820_mark_nosave_regions(void)
339 pfn
= PFN_DOWN(e820
.map
[0].addr
+ e820
.map
[0].size
);
340 for (i
= 1; i
< e820
.nr_map
; i
++) {
341 struct e820entry
*ei
= &e820
.map
[i
];
343 if (pfn
< PFN_UP(ei
->addr
))
344 register_nosave_region(pfn
, PFN_UP(ei
->addr
));
346 pfn
= PFN_DOWN(ei
->addr
+ ei
->size
);
347 if (ei
->type
!= E820_RAM
)
348 register_nosave_region(PFN_UP(ei
->addr
), pfn
);
350 if (pfn
>= max_low_pfn
)
356 void __init
add_memory_region(unsigned long long start
,
357 unsigned long long size
, int type
)
365 printk(KERN_ERR
"Ooops! Too many entries in the memory map!\n");
369 e820
.map
[x
].addr
= start
;
370 e820
.map
[x
].size
= size
;
371 e820
.map
[x
].type
= type
;
374 } /* add_memory_region */
377 * Sanitize the BIOS e820 map.
379 * Some e820 responses include overlapping entries. The following
380 * replaces the original e820 map with a new one, removing overlaps.
383 int __init
sanitize_e820_map(struct e820entry
* biosmap
, char * pnr_map
)
385 struct change_member
*change_tmp
;
386 unsigned long current_type
, last_type
;
387 unsigned long long last_addr
;
388 int chgidx
, still_changing
;
391 int old_nr
, new_nr
, chg_nr
;
395 Visually we're performing the following (1,2,3,4 = memory types)...
397 Sample memory map (w/overlaps):
398 ____22__________________
399 ______________________4_
400 ____1111________________
401 _44_____________________
402 11111111________________
403 ____________________33__
404 ___________44___________
405 __________33333_________
406 ______________22________
407 ___________________2222_
408 _________111111111______
409 _____________________11_
410 _________________4______
412 Sanitized equivalent (no overlap):
413 1_______________________
414 _44_____________________
415 ___1____________________
416 ____22__________________
417 ______11________________
418 _________1______________
419 __________3_____________
420 ___________44___________
421 _____________33_________
422 _______________2________
423 ________________1_______
424 _________________4______
425 ___________________2____
426 ____________________33__
427 ______________________4_
429 /* if there's only one memory region, don't bother */
436 /* bail out if we find any unreasonable addresses in bios map */
437 for (i
=0; i
<old_nr
; i
++)
438 if (biosmap
[i
].addr
+ biosmap
[i
].size
< biosmap
[i
].addr
) {
442 /* create pointers for initial change-point information (for sorting) */
443 for (i
=0; i
< 2*old_nr
; i
++)
444 change_point
[i
] = &change_point_list
[i
];
446 /* record all known change-points (starting and ending addresses),
447 omitting those that are for empty memory regions */
449 for (i
=0; i
< old_nr
; i
++) {
450 if (biosmap
[i
].size
!= 0) {
451 change_point
[chgidx
]->addr
= biosmap
[i
].addr
;
452 change_point
[chgidx
++]->pbios
= &biosmap
[i
];
453 change_point
[chgidx
]->addr
= biosmap
[i
].addr
+ biosmap
[i
].size
;
454 change_point
[chgidx
++]->pbios
= &biosmap
[i
];
457 chg_nr
= chgidx
; /* true number of change-points */
459 /* sort change-point list by memory addresses (low -> high) */
461 while (still_changing
) {
463 for (i
=1; i
< chg_nr
; i
++) {
464 /* if <current_addr> > <last_addr>, swap */
465 /* or, if current=<start_addr> & last=<end_addr>, swap */
466 if ((change_point
[i
]->addr
< change_point
[i
-1]->addr
) ||
467 ((change_point
[i
]->addr
== change_point
[i
-1]->addr
) &&
468 (change_point
[i
]->addr
== change_point
[i
]->pbios
->addr
) &&
469 (change_point
[i
-1]->addr
!= change_point
[i
-1]->pbios
->addr
))
472 change_tmp
= change_point
[i
];
473 change_point
[i
] = change_point
[i
-1];
474 change_point
[i
-1] = change_tmp
;
480 /* create a new bios memory map, removing overlaps */
481 overlap_entries
=0; /* number of entries in the overlap table */
482 new_bios_entry
=0; /* index for creating new bios map entries */
483 last_type
= 0; /* start with undefined memory type */
484 last_addr
= 0; /* start with 0 as last starting address */
485 /* loop through change-points, determining affect on the new bios map */
486 for (chgidx
=0; chgidx
< chg_nr
; chgidx
++)
488 /* keep track of all overlapping bios entries */
489 if (change_point
[chgidx
]->addr
== change_point
[chgidx
]->pbios
->addr
)
491 /* add map entry to overlap list (> 1 entry implies an overlap) */
492 overlap_list
[overlap_entries
++]=change_point
[chgidx
]->pbios
;
496 /* remove entry from list (order independent, so swap with last) */
497 for (i
=0; i
<overlap_entries
; i
++)
499 if (overlap_list
[i
] == change_point
[chgidx
]->pbios
)
500 overlap_list
[i
] = overlap_list
[overlap_entries
-1];
504 /* if there are overlapping entries, decide which "type" to use */
505 /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
507 for (i
=0; i
<overlap_entries
; i
++)
508 if (overlap_list
[i
]->type
> current_type
)
509 current_type
= overlap_list
[i
]->type
;
510 /* continue building up new bios map based on this information */
511 if (current_type
!= last_type
) {
512 if (last_type
!= 0) {
513 new_bios
[new_bios_entry
].size
=
514 change_point
[chgidx
]->addr
- last_addr
;
515 /* move forward only if the new size was non-zero */
516 if (new_bios
[new_bios_entry
].size
!= 0)
517 if (++new_bios_entry
>= E820MAX
)
518 break; /* no more space left for new bios entries */
520 if (current_type
!= 0) {
521 new_bios
[new_bios_entry
].addr
= change_point
[chgidx
]->addr
;
522 new_bios
[new_bios_entry
].type
= current_type
;
523 last_addr
=change_point
[chgidx
]->addr
;
525 last_type
= current_type
;
528 new_nr
= new_bios_entry
; /* retain count for new bios entries */
530 /* copy new bios mapping into original location */
531 memcpy(biosmap
, new_bios
, new_nr
*sizeof(struct e820entry
));
538 * Copy the BIOS e820 map into a safe place.
540 * Sanity-check it while we're at it..
542 * If we're lucky and live on a modern system, the setup code
543 * will have given us a memory map that we can use to properly
544 * set up memory. If we aren't, we'll fake a memory map.
546 * We check to see that the memory map contains at least 2 elements
547 * before we'll use it, because the detection code in setup.S may
548 * not be perfect and most every PC known to man has two memory
549 * regions: one from 0 to 640k, and one from 1mb up. (The IBM
550 * thinkpad 560x, for example, does not cooperate with the memory
553 int __init
copy_e820_map(struct e820entry
* biosmap
, int nr_map
)
555 /* Only one memory region (or negative)? Ignore it */
560 unsigned long long start
= biosmap
->addr
;
561 unsigned long long size
= biosmap
->size
;
562 unsigned long long end
= start
+ size
;
563 unsigned long type
= biosmap
->type
;
565 /* Overflow in 64 bits? Ignore the memory map. */
570 * Some BIOSes claim RAM in the 640k - 1M region.
571 * Not right. Fix it up.
573 if (type
== E820_RAM
) {
574 if (start
< 0x100000ULL
&& end
> 0xA0000ULL
) {
575 if (start
< 0xA0000ULL
)
576 add_memory_region(start
, 0xA0000ULL
-start
, type
);
577 if (end
<= 0x100000ULL
)
583 add_memory_region(start
, size
, type
);
584 } while (biosmap
++,--nr_map
);
589 * Callback for efi_memory_walk.
592 efi_find_max_pfn(unsigned long start
, unsigned long end
, void *arg
)
594 unsigned long *max_pfn
= arg
, pfn
;
597 pfn
= PFN_UP(end
-1);
605 efi_memory_present_wrapper(unsigned long start
, unsigned long end
, void *arg
)
607 memory_present(0, PFN_UP(start
), PFN_DOWN(end
));
612 * Find the highest page frame number we have available
614 void __init
find_max_pfn(void)
620 efi_memmap_walk(efi_find_max_pfn
, &max_pfn
);
621 efi_memmap_walk(efi_memory_present_wrapper
, NULL
);
625 for (i
= 0; i
< e820
.nr_map
; i
++) {
626 unsigned long start
, end
;
628 if (e820
.map
[i
].type
!= E820_RAM
)
630 start
= PFN_UP(e820
.map
[i
].addr
);
631 end
= PFN_DOWN(e820
.map
[i
].addr
+ e820
.map
[i
].size
);
636 memory_present(0, start
, end
);
641 * Free all available memory for boot time allocation. Used
642 * as a callback function by efi_memory_walk()
646 free_available_memory(unsigned long start
, unsigned long end
, void *arg
)
648 /* check max_low_pfn */
649 if (start
>= (max_low_pfn
<< PAGE_SHIFT
))
651 if (end
>= (max_low_pfn
<< PAGE_SHIFT
))
652 end
= max_low_pfn
<< PAGE_SHIFT
;
654 free_bootmem(start
, end
- start
);
659 * Register fully available low RAM pages with the bootmem allocator.
661 void __init
register_bootmem_low_pages(unsigned long max_low_pfn
)
666 efi_memmap_walk(free_available_memory
, NULL
);
669 for (i
= 0; i
< e820
.nr_map
; i
++) {
670 unsigned long curr_pfn
, last_pfn
, size
;
672 * Reserve usable low memory
674 if (e820
.map
[i
].type
!= E820_RAM
)
677 * We are rounding up the start address of usable memory:
679 curr_pfn
= PFN_UP(e820
.map
[i
].addr
);
680 if (curr_pfn
>= max_low_pfn
)
683 * ... and at the end of the usable range downwards:
685 last_pfn
= PFN_DOWN(e820
.map
[i
].addr
+ e820
.map
[i
].size
);
687 if (last_pfn
> max_low_pfn
)
688 last_pfn
= max_low_pfn
;
691 * .. finally, did all the rounding and playing
692 * around just make the area go away?
694 if (last_pfn
<= curr_pfn
)
697 size
= last_pfn
- curr_pfn
;
698 free_bootmem(PFN_PHYS(curr_pfn
), PFN_PHYS(size
));
702 void __init
e820_register_memory(void)
704 unsigned long gapstart
, gapsize
, round
;
705 unsigned long long last
;
709 * Search for the bigest gap in the low 32 bits of the e820
712 last
= 0x100000000ull
;
713 gapstart
= 0x10000000;
717 unsigned long long start
= e820
.map
[i
].addr
;
718 unsigned long long end
= start
+ e820
.map
[i
].size
;
721 * Since "last" is at most 4GB, we know we'll
722 * fit in 32 bits if this condition is true
725 unsigned long gap
= last
- end
;
737 * See how much we want to round up: start off with
738 * rounding to the next 1MB area.
741 while ((gapsize
>> 4) > round
)
743 /* Fun with two's complement */
744 pci_mem_start
= (gapstart
+ round
) & -round
;
746 printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
747 pci_mem_start
, gapstart
, gapsize
);
750 void __init
print_memory_map(char *who
)
754 for (i
= 0; i
< e820
.nr_map
; i
++) {
755 printk(" %s: %016Lx - %016Lx ", who
,
757 e820
.map
[i
].addr
+ e820
.map
[i
].size
);
758 switch (e820
.map
[i
].type
) {
759 case E820_RAM
: printk("(usable)\n");
762 printk("(reserved)\n");
765 printk("(ACPI data)\n");
768 printk("(ACPI NVS)\n");
770 default: printk("type %u\n", e820
.map
[i
].type
);
776 static __init __always_inline
void efi_limit_regions(unsigned long long size
)
778 unsigned long long current_addr
= 0;
779 efi_memory_desc_t
*md
, *next_md
;
785 for (p
= p1
, i
= 0; p
< memmap
.map_end
; p
+= memmap
.desc_size
, i
++) {
788 current_addr
= md
->phys_addr
+
789 PFN_PHYS(md
->num_pages
);
790 if (is_available_memory(md
)) {
791 if (md
->phys_addr
>= size
) continue;
792 memcpy(next_md
, md
, memmap
.desc_size
);
793 if (current_addr
>= size
) {
794 next_md
->num_pages
-=
795 PFN_UP(current_addr
-size
);
797 p1
+= memmap
.desc_size
;
800 } else if ((md
->attribute
& EFI_MEMORY_RUNTIME
) ==
801 EFI_MEMORY_RUNTIME
) {
802 /* In order to make runtime services
803 * available we have to include runtime
804 * memory regions in memory map */
805 memcpy(next_md
, md
, memmap
.desc_size
);
806 p1
+= memmap
.desc_size
;
812 memmap
.map_end
= memmap
.map
+
813 (memmap
.nr_map
* memmap
.desc_size
);
816 void __init
limit_regions(unsigned long long size
)
818 unsigned long long current_addr
;
821 print_memory_map("limit_regions start");
823 efi_limit_regions(size
);
826 for (i
= 0; i
< e820
.nr_map
; i
++) {
827 current_addr
= e820
.map
[i
].addr
+ e820
.map
[i
].size
;
828 if (current_addr
< size
)
831 if (e820
.map
[i
].type
!= E820_RAM
)
834 if (e820
.map
[i
].addr
>= size
) {
836 * This region starts past the end of the
837 * requested size, skip it completely.
842 e820
.map
[i
].size
-= current_addr
- size
;
844 print_memory_map("limit_regions endfor");
847 print_memory_map("limit_regions endfunc");
851 * This function checks if any part of the range <start,end> is mapped
855 e820_any_mapped(u64 start
, u64 end
, unsigned type
)
858 for (i
= 0; i
< e820
.nr_map
; i
++) {
859 const struct e820entry
*ei
= &e820
.map
[i
];
860 if (type
&& ei
->type
!= type
)
862 if (ei
->addr
>= end
|| ei
->addr
+ ei
->size
<= start
)
868 EXPORT_SYMBOL_GPL(e820_any_mapped
);
871 * This function checks if the entire range <start,end> is mapped with type.
873 * Note: this function only works correct if the e820 table is sorted and
874 * not-overlapping, which is the case
877 e820_all_mapped(unsigned long s
, unsigned long e
, unsigned type
)
882 for (i
= 0; i
< e820
.nr_map
; i
++) {
883 struct e820entry
*ei
= &e820
.map
[i
];
884 if (type
&& ei
->type
!= type
)
886 /* is the region (part) in overlap with the current region ?*/
887 if (ei
->addr
>= end
|| ei
->addr
+ ei
->size
<= start
)
889 /* if the region is at the beginning of <start,end> we move
890 * start to the end of the region since it's ok until there
892 if (ei
->addr
<= start
)
893 start
= ei
->addr
+ ei
->size
;
894 /* if start is now at or beyond end, we're done, full
897 return 1; /* we're done */
902 static int __init
parse_memmap(char *arg
)
907 if (strcmp(arg
, "exactmap") == 0) {
908 #ifdef CONFIG_CRASH_DUMP
909 /* If we are doing a crash dump, we
910 * still need to know the real mem
911 * size before original memory map is
915 saved_max_pfn
= max_pfn
;
918 user_defined_memmap
= 1;
920 /* If the user specifies memory size, we
921 * limit the BIOS-provided memory map to
922 * that size. exactmap can be used to specify
923 * the exact map. mem=number can be used to
924 * trim the existing memory map.
926 unsigned long long start_at
, mem_size
;
928 mem_size
= memparse(arg
, &arg
);
930 start_at
= memparse(arg
+1, &arg
);
931 add_memory_region(start_at
, mem_size
, E820_RAM
);
932 } else if (*arg
== '#') {
933 start_at
= memparse(arg
+1, &arg
);
934 add_memory_region(start_at
, mem_size
, E820_ACPI
);
935 } else if (*arg
== '$') {
936 start_at
= memparse(arg
+1, &arg
);
937 add_memory_region(start_at
, mem_size
, E820_RESERVED
);
939 limit_regions(mem_size
);
940 user_defined_memmap
= 1;
945 early_param("memmap", parse_memmap
);