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 struct resource bss_resource
= {
58 .flags
= IORESOURCE_BUSY
| IORESOURCE_MEM
61 static struct resource system_rom_resource
= {
65 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
68 static struct resource extension_rom_resource
= {
69 .name
= "Extension ROM",
72 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
75 static struct resource adapter_rom_resources
[] = { {
76 .name
= "Adapter ROM",
79 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
81 .name
= "Adapter ROM",
84 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
86 .name
= "Adapter ROM",
89 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
91 .name
= "Adapter ROM",
94 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
96 .name
= "Adapter ROM",
99 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
101 .name
= "Adapter ROM",
104 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
107 static struct resource video_rom_resource
= {
111 .flags
= IORESOURCE_BUSY
| IORESOURCE_READONLY
| IORESOURCE_MEM
114 static struct resource video_ram_resource
= {
115 .name
= "Video RAM area",
118 .flags
= IORESOURCE_BUSY
| IORESOURCE_MEM
121 static struct resource standard_io_resources
[] = { {
125 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
130 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
135 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
140 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
145 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
147 .name
= "dma page reg",
150 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
155 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
160 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
165 .flags
= IORESOURCE_BUSY
| IORESOURCE_IO
168 #define ROMSIGNATURE 0xaa55
170 static int __init
romsignature(const unsigned char *rom
)
172 const unsigned short * const ptr
= (const unsigned short *)rom
;
175 return probe_kernel_address(ptr
, sig
) == 0 && sig
== ROMSIGNATURE
;
178 static int __init
romchecksum(const unsigned char *rom
, unsigned long length
)
180 unsigned char sum
, c
;
182 for (sum
= 0; length
&& probe_kernel_address(rom
++, c
) == 0; length
--)
184 return !length
&& !sum
;
187 static void __init
probe_roms(void)
189 const unsigned char *rom
;
190 unsigned long start
, length
, upper
;
195 upper
= adapter_rom_resources
[0].start
;
196 for (start
= video_rom_resource
.start
; start
< upper
; start
+= 2048) {
197 rom
= isa_bus_to_virt(start
);
198 if (!romsignature(rom
))
201 video_rom_resource
.start
= start
;
203 if (probe_kernel_address(rom
+ 2, c
) != 0)
206 /* 0 < length <= 0x7f * 512, historically */
209 /* if checksum okay, trust length byte */
210 if (length
&& romchecksum(rom
, length
))
211 video_rom_resource
.end
= start
+ length
- 1;
213 request_resource(&iomem_resource
, &video_rom_resource
);
217 start
= (video_rom_resource
.end
+ 1 + 2047) & ~2047UL;
222 request_resource(&iomem_resource
, &system_rom_resource
);
223 upper
= system_rom_resource
.start
;
225 /* check for extension rom (ignore length byte!) */
226 rom
= isa_bus_to_virt(extension_rom_resource
.start
);
227 if (romsignature(rom
)) {
228 length
= extension_rom_resource
.end
- extension_rom_resource
.start
+ 1;
229 if (romchecksum(rom
, length
)) {
230 request_resource(&iomem_resource
, &extension_rom_resource
);
231 upper
= extension_rom_resource
.start
;
235 /* check for adapter roms on 2k boundaries */
236 for (i
= 0; i
< ARRAY_SIZE(adapter_rom_resources
) && start
< upper
; start
+= 2048) {
237 rom
= isa_bus_to_virt(start
);
238 if (!romsignature(rom
))
241 if (probe_kernel_address(rom
+ 2, c
) != 0)
244 /* 0 < length <= 0x7f * 512, historically */
247 /* but accept any length that fits if checksum okay */
248 if (!length
|| start
+ length
> upper
|| !romchecksum(rom
, length
))
251 adapter_rom_resources
[i
].start
= start
;
252 adapter_rom_resources
[i
].end
= start
+ length
- 1;
253 request_resource(&iomem_resource
, &adapter_rom_resources
[i
]);
255 start
= adapter_rom_resources
[i
++].end
& ~2047UL;
260 * Request address space for all standard RAM and ROM resources
261 * and also for regions reported as reserved by the e820.
264 legacy_init_iomem_resources(struct resource
*code_resource
,
265 struct resource
*data_resource
,
266 struct resource
*bss_resource
)
271 for (i
= 0; i
< e820
.nr_map
; i
++) {
272 struct resource
*res
;
273 #ifndef CONFIG_RESOURCES_64BIT
274 if (e820
.map
[i
].addr
+ e820
.map
[i
].size
> 0x100000000ULL
)
277 res
= kzalloc(sizeof(struct resource
), GFP_ATOMIC
);
278 switch (e820
.map
[i
].type
) {
279 case E820_RAM
: res
->name
= "System RAM"; break;
280 case E820_ACPI
: res
->name
= "ACPI Tables"; break;
281 case E820_NVS
: res
->name
= "ACPI Non-volatile Storage"; break;
282 default: res
->name
= "reserved";
284 res
->start
= e820
.map
[i
].addr
;
285 res
->end
= res
->start
+ e820
.map
[i
].size
- 1;
286 res
->flags
= IORESOURCE_MEM
| IORESOURCE_BUSY
;
287 if (request_resource(&iomem_resource
, res
)) {
291 if (e820
.map
[i
].type
== E820_RAM
) {
293 * We don't know which RAM region contains kernel data,
294 * so we try it repeatedly and let the resource manager
297 request_resource(res
, code_resource
);
298 request_resource(res
, data_resource
);
299 request_resource(res
, bss_resource
);
301 if (crashk_res
.start
!= crashk_res
.end
)
302 request_resource(res
, &crashk_res
);
309 * Request address space for all standard resources
311 * This is called just before pcibios_init(), which is also a
312 * subsys_initcall, but is linked in later (in arch/i386/pci/common.c).
314 static int __init
request_standard_resources(void)
318 printk("Setting up standard PCI resources\n");
320 efi_initialize_iomem_resources(&code_resource
,
321 &data_resource
, &bss_resource
);
323 legacy_init_iomem_resources(&code_resource
,
324 &data_resource
, &bss_resource
);
326 /* EFI systems may still have VGA */
327 request_resource(&iomem_resource
, &video_ram_resource
);
329 /* request I/O space for devices used on all i[345]86 PCs */
330 for (i
= 0; i
< ARRAY_SIZE(standard_io_resources
); i
++)
331 request_resource(&ioport_resource
, &standard_io_resources
[i
]);
335 subsys_initcall(request_standard_resources
);
337 #if defined(CONFIG_PM) && defined(CONFIG_HIBERNATION)
339 * e820_mark_nosave_regions - Find the ranges of physical addresses that do not
340 * correspond to e820 RAM areas and mark the corresponding pages as nosave for
343 * This function requires the e820 map to be sorted and without any
344 * overlapping entries and assumes the first e820 area to be RAM.
346 void __init
e820_mark_nosave_regions(void)
351 pfn
= PFN_DOWN(e820
.map
[0].addr
+ e820
.map
[0].size
);
352 for (i
= 1; i
< e820
.nr_map
; i
++) {
353 struct e820entry
*ei
= &e820
.map
[i
];
355 if (pfn
< PFN_UP(ei
->addr
))
356 register_nosave_region(pfn
, PFN_UP(ei
->addr
));
358 pfn
= PFN_DOWN(ei
->addr
+ ei
->size
);
359 if (ei
->type
!= E820_RAM
)
360 register_nosave_region(PFN_UP(ei
->addr
), pfn
);
362 if (pfn
>= max_low_pfn
)
368 void __init
add_memory_region(unsigned long long start
,
369 unsigned long long size
, int type
)
377 printk(KERN_ERR
"Ooops! Too many entries in the memory map!\n");
381 e820
.map
[x
].addr
= start
;
382 e820
.map
[x
].size
= size
;
383 e820
.map
[x
].type
= type
;
386 } /* add_memory_region */
389 * Sanitize the BIOS e820 map.
391 * Some e820 responses include overlapping entries. The following
392 * replaces the original e820 map with a new one, removing overlaps.
395 int __init
sanitize_e820_map(struct e820entry
* biosmap
, char * pnr_map
)
397 struct change_member
*change_tmp
;
398 unsigned long current_type
, last_type
;
399 unsigned long long last_addr
;
400 int chgidx
, still_changing
;
403 int old_nr
, new_nr
, chg_nr
;
407 Visually we're performing the following (1,2,3,4 = memory types)...
409 Sample memory map (w/overlaps):
410 ____22__________________
411 ______________________4_
412 ____1111________________
413 _44_____________________
414 11111111________________
415 ____________________33__
416 ___________44___________
417 __________33333_________
418 ______________22________
419 ___________________2222_
420 _________111111111______
421 _____________________11_
422 _________________4______
424 Sanitized equivalent (no overlap):
425 1_______________________
426 _44_____________________
427 ___1____________________
428 ____22__________________
429 ______11________________
430 _________1______________
431 __________3_____________
432 ___________44___________
433 _____________33_________
434 _______________2________
435 ________________1_______
436 _________________4______
437 ___________________2____
438 ____________________33__
439 ______________________4_
441 /* if there's only one memory region, don't bother */
448 /* bail out if we find any unreasonable addresses in bios map */
449 for (i
=0; i
<old_nr
; i
++)
450 if (biosmap
[i
].addr
+ biosmap
[i
].size
< biosmap
[i
].addr
) {
454 /* create pointers for initial change-point information (for sorting) */
455 for (i
=0; i
< 2*old_nr
; i
++)
456 change_point
[i
] = &change_point_list
[i
];
458 /* record all known change-points (starting and ending addresses),
459 omitting those that are for empty memory regions */
461 for (i
=0; i
< old_nr
; i
++) {
462 if (biosmap
[i
].size
!= 0) {
463 change_point
[chgidx
]->addr
= biosmap
[i
].addr
;
464 change_point
[chgidx
++]->pbios
= &biosmap
[i
];
465 change_point
[chgidx
]->addr
= biosmap
[i
].addr
+ biosmap
[i
].size
;
466 change_point
[chgidx
++]->pbios
= &biosmap
[i
];
469 chg_nr
= chgidx
; /* true number of change-points */
471 /* sort change-point list by memory addresses (low -> high) */
473 while (still_changing
) {
475 for (i
=1; i
< chg_nr
; i
++) {
476 /* if <current_addr> > <last_addr>, swap */
477 /* or, if current=<start_addr> & last=<end_addr>, swap */
478 if ((change_point
[i
]->addr
< change_point
[i
-1]->addr
) ||
479 ((change_point
[i
]->addr
== change_point
[i
-1]->addr
) &&
480 (change_point
[i
]->addr
== change_point
[i
]->pbios
->addr
) &&
481 (change_point
[i
-1]->addr
!= change_point
[i
-1]->pbios
->addr
))
484 change_tmp
= change_point
[i
];
485 change_point
[i
] = change_point
[i
-1];
486 change_point
[i
-1] = change_tmp
;
492 /* create a new bios memory map, removing overlaps */
493 overlap_entries
=0; /* number of entries in the overlap table */
494 new_bios_entry
=0; /* index for creating new bios map entries */
495 last_type
= 0; /* start with undefined memory type */
496 last_addr
= 0; /* start with 0 as last starting address */
497 /* loop through change-points, determining affect on the new bios map */
498 for (chgidx
=0; chgidx
< chg_nr
; chgidx
++)
500 /* keep track of all overlapping bios entries */
501 if (change_point
[chgidx
]->addr
== change_point
[chgidx
]->pbios
->addr
)
503 /* add map entry to overlap list (> 1 entry implies an overlap) */
504 overlap_list
[overlap_entries
++]=change_point
[chgidx
]->pbios
;
508 /* remove entry from list (order independent, so swap with last) */
509 for (i
=0; i
<overlap_entries
; i
++)
511 if (overlap_list
[i
] == change_point
[chgidx
]->pbios
)
512 overlap_list
[i
] = overlap_list
[overlap_entries
-1];
516 /* if there are overlapping entries, decide which "type" to use */
517 /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
519 for (i
=0; i
<overlap_entries
; i
++)
520 if (overlap_list
[i
]->type
> current_type
)
521 current_type
= overlap_list
[i
]->type
;
522 /* continue building up new bios map based on this information */
523 if (current_type
!= last_type
) {
524 if (last_type
!= 0) {
525 new_bios
[new_bios_entry
].size
=
526 change_point
[chgidx
]->addr
- last_addr
;
527 /* move forward only if the new size was non-zero */
528 if (new_bios
[new_bios_entry
].size
!= 0)
529 if (++new_bios_entry
>= E820MAX
)
530 break; /* no more space left for new bios entries */
532 if (current_type
!= 0) {
533 new_bios
[new_bios_entry
].addr
= change_point
[chgidx
]->addr
;
534 new_bios
[new_bios_entry
].type
= current_type
;
535 last_addr
=change_point
[chgidx
]->addr
;
537 last_type
= current_type
;
540 new_nr
= new_bios_entry
; /* retain count for new bios entries */
542 /* copy new bios mapping into original location */
543 memcpy(biosmap
, new_bios
, new_nr
*sizeof(struct e820entry
));
550 * Copy the BIOS e820 map into a safe place.
552 * Sanity-check it while we're at it..
554 * If we're lucky and live on a modern system, the setup code
555 * will have given us a memory map that we can use to properly
556 * set up memory. If we aren't, we'll fake a memory map.
558 * We check to see that the memory map contains at least 2 elements
559 * before we'll use it, because the detection code in setup.S may
560 * not be perfect and most every PC known to man has two memory
561 * regions: one from 0 to 640k, and one from 1mb up. (The IBM
562 * thinkpad 560x, for example, does not cooperate with the memory
565 int __init
copy_e820_map(struct e820entry
* biosmap
, int nr_map
)
567 /* Only one memory region (or negative)? Ignore it */
572 unsigned long long start
= biosmap
->addr
;
573 unsigned long long size
= biosmap
->size
;
574 unsigned long long end
= start
+ size
;
575 unsigned long type
= biosmap
->type
;
577 /* Overflow in 64 bits? Ignore the memory map. */
582 * Some BIOSes claim RAM in the 640k - 1M region.
583 * Not right. Fix it up.
585 if (type
== E820_RAM
) {
586 if (start
< 0x100000ULL
&& end
> 0xA0000ULL
) {
587 if (start
< 0xA0000ULL
)
588 add_memory_region(start
, 0xA0000ULL
-start
, type
);
589 if (end
<= 0x100000ULL
)
595 add_memory_region(start
, size
, type
);
596 } while (biosmap
++,--nr_map
);
601 * Callback for efi_memory_walk.
604 efi_find_max_pfn(unsigned long start
, unsigned long end
, void *arg
)
606 unsigned long *max_pfn
= arg
, pfn
;
609 pfn
= PFN_UP(end
-1);
617 efi_memory_present_wrapper(unsigned long start
, unsigned long end
, void *arg
)
619 memory_present(0, PFN_UP(start
), PFN_DOWN(end
));
624 * Find the highest page frame number we have available
626 void __init
find_max_pfn(void)
632 efi_memmap_walk(efi_find_max_pfn
, &max_pfn
);
633 efi_memmap_walk(efi_memory_present_wrapper
, NULL
);
637 for (i
= 0; i
< e820
.nr_map
; i
++) {
638 unsigned long start
, end
;
640 if (e820
.map
[i
].type
!= E820_RAM
)
642 start
= PFN_UP(e820
.map
[i
].addr
);
643 end
= PFN_DOWN(e820
.map
[i
].addr
+ e820
.map
[i
].size
);
648 memory_present(0, start
, end
);
653 * Free all available memory for boot time allocation. Used
654 * as a callback function by efi_memory_walk()
658 free_available_memory(unsigned long start
, unsigned long end
, void *arg
)
660 /* check max_low_pfn */
661 if (start
>= (max_low_pfn
<< PAGE_SHIFT
))
663 if (end
>= (max_low_pfn
<< PAGE_SHIFT
))
664 end
= max_low_pfn
<< PAGE_SHIFT
;
666 free_bootmem(start
, end
- start
);
671 * Register fully available low RAM pages with the bootmem allocator.
673 void __init
register_bootmem_low_pages(unsigned long max_low_pfn
)
678 efi_memmap_walk(free_available_memory
, NULL
);
681 for (i
= 0; i
< e820
.nr_map
; i
++) {
682 unsigned long curr_pfn
, last_pfn
, size
;
684 * Reserve usable low memory
686 if (e820
.map
[i
].type
!= E820_RAM
)
689 * We are rounding up the start address of usable memory:
691 curr_pfn
= PFN_UP(e820
.map
[i
].addr
);
692 if (curr_pfn
>= max_low_pfn
)
695 * ... and at the end of the usable range downwards:
697 last_pfn
= PFN_DOWN(e820
.map
[i
].addr
+ e820
.map
[i
].size
);
699 if (last_pfn
> max_low_pfn
)
700 last_pfn
= max_low_pfn
;
703 * .. finally, did all the rounding and playing
704 * around just make the area go away?
706 if (last_pfn
<= curr_pfn
)
709 size
= last_pfn
- curr_pfn
;
710 free_bootmem(PFN_PHYS(curr_pfn
), PFN_PHYS(size
));
714 void __init
e820_register_memory(void)
716 unsigned long gapstart
, gapsize
, round
;
717 unsigned long long last
;
721 * Search for the biggest gap in the low 32 bits of the e820
724 last
= 0x100000000ull
;
725 gapstart
= 0x10000000;
729 unsigned long long start
= e820
.map
[i
].addr
;
730 unsigned long long end
= start
+ e820
.map
[i
].size
;
733 * Since "last" is at most 4GB, we know we'll
734 * fit in 32 bits if this condition is true
737 unsigned long gap
= last
- end
;
749 * See how much we want to round up: start off with
750 * rounding to the next 1MB area.
753 while ((gapsize
>> 4) > round
)
755 /* Fun with two's complement */
756 pci_mem_start
= (gapstart
+ round
) & -round
;
758 printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
759 pci_mem_start
, gapstart
, gapsize
);
762 void __init
print_memory_map(char *who
)
766 for (i
= 0; i
< e820
.nr_map
; i
++) {
767 printk(" %s: %016Lx - %016Lx ", who
,
769 e820
.map
[i
].addr
+ e820
.map
[i
].size
);
770 switch (e820
.map
[i
].type
) {
771 case E820_RAM
: printk("(usable)\n");
774 printk("(reserved)\n");
777 printk("(ACPI data)\n");
780 printk("(ACPI NVS)\n");
782 default: printk("type %u\n", e820
.map
[i
].type
);
788 static __init __always_inline
void efi_limit_regions(unsigned long long size
)
790 unsigned long long current_addr
= 0;
791 efi_memory_desc_t
*md
, *next_md
;
797 for (p
= p1
, i
= 0; p
< memmap
.map_end
; p
+= memmap
.desc_size
, i
++) {
800 current_addr
= md
->phys_addr
+
801 PFN_PHYS(md
->num_pages
);
802 if (is_available_memory(md
)) {
803 if (md
->phys_addr
>= size
) continue;
804 memcpy(next_md
, md
, memmap
.desc_size
);
805 if (current_addr
>= size
) {
806 next_md
->num_pages
-=
807 PFN_UP(current_addr
-size
);
809 p1
+= memmap
.desc_size
;
812 } else if ((md
->attribute
& EFI_MEMORY_RUNTIME
) ==
813 EFI_MEMORY_RUNTIME
) {
814 /* In order to make runtime services
815 * available we have to include runtime
816 * memory regions in memory map */
817 memcpy(next_md
, md
, memmap
.desc_size
);
818 p1
+= memmap
.desc_size
;
824 memmap
.map_end
= memmap
.map
+
825 (memmap
.nr_map
* memmap
.desc_size
);
828 void __init
limit_regions(unsigned long long size
)
830 unsigned long long current_addr
;
833 print_memory_map("limit_regions start");
835 efi_limit_regions(size
);
838 for (i
= 0; i
< e820
.nr_map
; i
++) {
839 current_addr
= e820
.map
[i
].addr
+ e820
.map
[i
].size
;
840 if (current_addr
< size
)
843 if (e820
.map
[i
].type
!= E820_RAM
)
846 if (e820
.map
[i
].addr
>= size
) {
848 * This region starts past the end of the
849 * requested size, skip it completely.
854 e820
.map
[i
].size
-= current_addr
- size
;
856 print_memory_map("limit_regions endfor");
859 print_memory_map("limit_regions endfunc");
863 * This function checks if any part of the range <start,end> is mapped
867 e820_any_mapped(u64 start
, u64 end
, unsigned type
)
870 for (i
= 0; i
< e820
.nr_map
; i
++) {
871 const struct e820entry
*ei
= &e820
.map
[i
];
872 if (type
&& ei
->type
!= type
)
874 if (ei
->addr
>= end
|| ei
->addr
+ ei
->size
<= start
)
880 EXPORT_SYMBOL_GPL(e820_any_mapped
);
883 * This function checks if the entire range <start,end> is mapped with type.
885 * Note: this function only works correct if the e820 table is sorted and
886 * not-overlapping, which is the case
889 e820_all_mapped(unsigned long s
, unsigned long e
, unsigned type
)
894 for (i
= 0; i
< e820
.nr_map
; i
++) {
895 struct e820entry
*ei
= &e820
.map
[i
];
896 if (type
&& ei
->type
!= type
)
898 /* is the region (part) in overlap with the current region ?*/
899 if (ei
->addr
>= end
|| ei
->addr
+ ei
->size
<= start
)
901 /* if the region is at the beginning of <start,end> we move
902 * start to the end of the region since it's ok until there
904 if (ei
->addr
<= start
)
905 start
= ei
->addr
+ ei
->size
;
906 /* if start is now at or beyond end, we're done, full
909 return 1; /* we're done */
914 static int __init
parse_memmap(char *arg
)
919 if (strcmp(arg
, "exactmap") == 0) {
920 #ifdef CONFIG_CRASH_DUMP
921 /* If we are doing a crash dump, we
922 * still need to know the real mem
923 * size before original memory map is
927 saved_max_pfn
= max_pfn
;
930 user_defined_memmap
= 1;
932 /* If the user specifies memory size, we
933 * limit the BIOS-provided memory map to
934 * that size. exactmap can be used to specify
935 * the exact map. mem=number can be used to
936 * trim the existing memory map.
938 unsigned long long start_at
, mem_size
;
940 mem_size
= memparse(arg
, &arg
);
942 start_at
= memparse(arg
+1, &arg
);
943 add_memory_region(start_at
, mem_size
, E820_RAM
);
944 } else if (*arg
== '#') {
945 start_at
= memparse(arg
+1, &arg
);
946 add_memory_region(start_at
, mem_size
, E820_ACPI
);
947 } else if (*arg
== '$') {
948 start_at
= memparse(arg
+1, &arg
);
949 add_memory_region(start_at
, mem_size
, E820_RESERVED
);
951 limit_regions(mem_size
);
952 user_defined_memmap
= 1;
957 early_param("memmap", parse_memmap
);