arch/x86_64/kernel/e820.c - linux-3.10 - Gitiles Standalone

 /*
  * Handle the memory map.
  * The functions here do the job until bootmem takes over.
  * $Id: e820.c,v 1.4 2002/09/19 19:25:32 ak Exp $
  */
 #include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/ioport.h>
 #include <linux/string.h>
 #include <asm/page.h>
 #include <asm/e820.h>
 #include <asm/proto.h>
 #include <asm/bootsetup.h>

 extern char _end[];

 /*
  * PFN of last memory page.
  */
 unsigned long end_pfn;

 /*
  * end_pfn only includes RAM, while end_pfn_map includes all e820 entries.
  * The direct mapping extends to end_pfn_map, so that we can directly access
  * apertures, ACPI and other tables without having to play with fixmaps.
  */
 unsigned long end_pfn_map;

 /*
  * Last pfn which the user wants to use.
  */
 unsigned long end_user_pfn = MAXMEM>>PAGE_SHIFT;

 extern struct resource code_resource, data_resource;

 /* Check for some hardcoded bad areas that early boot is not allowed to touch */
 static inline int bad_addr(unsigned long *addrp, unsigned long size)
 {
 	unsigned long addr = *addrp, last = addr + size;

 	/* various gunk below that needed for SMP startup */
 	if (addr < 0x8000) {
 		*addrp = 0x8000;
 		return 1;
 	}

 	/* direct mapping tables of the kernel */
 	if (last >= table_start<<PAGE_SHIFT && addr < table_end<<PAGE_SHIFT) {
 		*addrp = table_end << PAGE_SHIFT;
 		return 1;
 	}

 	/* initrd */
 #ifdef CONFIG_BLK_DEV_INITRD
 	if (LOADER_TYPE && INITRD_START && last >= INITRD_START &&
 	    addr < INITRD_START+INITRD_SIZE) {
 		*addrp = INITRD_START + INITRD_SIZE;
 		return 1;
 	}
 #endif
 	/* kernel code + 640k memory hole (later should not be needed, but
 	   be paranoid for now) */
 	if (last >= 640*1024 && addr < __pa_symbol(&_end)) {
 		*addrp = __pa_symbol(&_end);
 		return 1;
 	}
 	/* XXX ramdisk image here? */
 	return 0;
 }

 int __init e820_mapped(unsigned long start, unsigned long end, unsigned type)
 {
 	int i;
 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 		if (type && ei->type != type)
 			continue;
 		if (ei->addr >= end || ei->addr + ei->size < start)
 			continue;
 		return 1;
 	}
 	return 0;
 }

 /*
  * Find a free area in a specific range.
  */
 unsigned long __init find_e820_area(unsigned long start, unsigned long end, unsigned size)
 {
 	int i;
 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 		unsigned long addr = ei->addr, last;
 		if (ei->type != E820_RAM)
 			continue;
 		if (addr < start)
 			addr = start;
 		if (addr > ei->addr + ei->size)
 			continue;
 		while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size)
 			;
 		last = addr + size;
 		if (last > ei->addr + ei->size)
 			continue;
 		if (last > end)
 			continue;
 		return addr;
 	}
 	return -1UL;
 }

 /*
  * Free bootmem based on the e820 table for a node.
  */
 void __init e820_bootmem_free(pg_data_t *pgdat, unsigned long start,unsigned long end)
 {
 	int i;
 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 		unsigned long last, addr;

 		if (ei->type != E820_RAM ||
 		    ei->addr+ei->size <= start ||
 		    ei->addr > end)
 			continue;

 		addr = round_up(ei->addr, PAGE_SIZE);
 		if (addr < start)
 			addr = start;

 		last = round_down(ei->addr + ei->size, PAGE_SIZE);
 		if (last >= end)
 			last = end;

 		if (last > addr && last-addr >= PAGE_SIZE)
 			free_bootmem_node(pgdat, addr, last-addr);
 	}
 }

 /*
  * Find the highest page frame number we have available
  */
 unsigned long __init e820_end_of_ram(void)
 {
 	int i;
 	unsigned long end_pfn = 0;

 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 		unsigned long start, end;

 		start = round_up(ei->addr, PAGE_SIZE);
 		end = round_down(ei->addr + ei->size, PAGE_SIZE);
 		if (start >= end)
 			continue;
 		if (ei->type == E820_RAM) {
 		if (end > end_pfn<<PAGE_SHIFT)
 			end_pfn = end>>PAGE_SHIFT;
 		} else {
 			if (end > end_pfn_map<<PAGE_SHIFT)
 				end_pfn_map = end>>PAGE_SHIFT;
 		}
 	}

 	if (end_pfn > end_pfn_map)
 		end_pfn_map = end_pfn;
 	if (end_pfn_map > MAXMEM>>PAGE_SHIFT)
 		end_pfn_map = MAXMEM>>PAGE_SHIFT;
 	if (end_pfn > end_user_pfn)
 		end_pfn = end_user_pfn;
 	if (end_pfn > end_pfn_map)
 		end_pfn = end_pfn_map;

 	return end_pfn;
 }

 /*
  * Mark e820 reserved areas as busy for the resource manager.
  */
 void __init e820_reserve_resources(void)
 {
 	int i;
 	for (i = 0; i < e820.nr_map; i++) {
 		struct resource *res;
 		if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
 			continue;
 		res = alloc_bootmem_low(sizeof(struct resource));
 		switch (e820.map[i].type) {
 		case E820_RAM:	res->name = "System RAM"; break;
 		case E820_ACPI:	res->name = "ACPI Tables"; break;
 		case E820_NVS:	res->name = "ACPI Non-volatile Storage"; break;
 		default:	res->name = "reserved";
 		}
 		res->start = e820.map[i].addr;
 		res->end = res->start + e820.map[i].size - 1;
 		res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		request_resource(&iomem_resource, res);
 		if (e820.map[i].type == E820_RAM) {
 			/*
 			 *  We don't know which RAM region contains kernel data,
 			 *  so we try it repeatedly and let the resource manager
 			 *  test it.
 			 */
 			request_resource(res, &code_resource);
 			request_resource(res, &data_resource);
 		}
 	}
 }

 /*
  * Add a memory region to the kernel e820 map.
  */
 void __init add_memory_region(unsigned long start, unsigned long size, int type)
 {
 	int x = e820.nr_map;

 	if (x == E820MAX) {
 		printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
 		return;
 	}

 	e820.map[x].addr = start;
 	e820.map[x].size = size;
 	e820.map[x].type = type;
 	e820.nr_map++;
 }

 void __init e820_print_map(char *who)
 {
 	int i;

 	for (i = 0; i < e820.nr_map; i++) {
 		printk(" %s: %016Lx - %016Lx ", who,
 			(unsigned long long) e820.map[i].addr,
 			(unsigned long long) (e820.map[i].addr + e820.map[i].size));
 		switch (e820.map[i].type) {
 		case E820_RAM:	printk("(usable)\n");
 				break;
 		case E820_RESERVED:
 				printk("(reserved)\n");
 				break;
 		case E820_ACPI:
 				printk("(ACPI data)\n");
 				break;
 		case E820_NVS:
 				printk("(ACPI NVS)\n");
 				break;
 		default:	printk("type %u\n", e820.map[i].type);
 				break;
 		}
 	}
 }

 /*
  * Sanitize the BIOS e820 map.
  *
  * Some e820 responses include overlapping entries.  The following
  * replaces the original e820 map with a new one, removing overlaps.
  *
  */
 static int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
 {
 	struct change_member {
 		struct e820entry *pbios; /* pointer to original bios entry */
 		unsigned long long addr; /* address for this change point */
 	};
 	static struct change_member change_point_list[2*E820MAX] __initdata;
 	static struct change_member *change_point[2*E820MAX] __initdata;
 	static struct e820entry *overlap_list[E820MAX] __initdata;
 	static struct e820entry new_bios[E820MAX] __initdata;
 	struct change_member *change_tmp;
 	unsigned long current_type, last_type;
 	unsigned long long last_addr;
 	int chgidx, still_changing;
 	int overlap_entries;
 	int new_bios_entry;
 	int old_nr, new_nr;
 	int i;

 	/*
 		Visually we're performing the following (1,2,3,4 = memory types)...

 		Sample memory map (w/overlaps):
 		   ____22__________________
 		   ______________________4_
 		   ____1111________________
 		   _44_____________________
 		   11111111________________
 		   ____________________33__
 		   ___________44___________
 		   __________33333_________
 		   ______________22________
 		   ___________________2222_
 		   _________111111111______
 		   _____________________11_
 		   _________________4______

 		Sanitized equivalent (no overlap):
 		   1_______________________
 		   _44_____________________
 		   ___1____________________
 		   ____22__________________
 		   ______11________________
 		   _________1______________
 		   __________3_____________
 		   ___________44___________
 		   _____________33_________
 		   _______________2________
 		   ________________1_______
 		   _________________4______
 		   ___________________2____
 		   ____________________33__
 		   ______________________4_
 	*/

 	/* if there's only one memory region, don't bother */
 	if (*pnr_map < 2)
 		return -1;

 	old_nr = *pnr_map;

 	/* bail out if we find any unreasonable addresses in bios map */
 	for (i=0; i<old_nr; i++)
 		if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr)
 			return -1;

 	/* create pointers for initial change-point information (for sorting) */
 	for (i=0; i < 2*old_nr; i++)
 		change_point[i] = &change_point_list[i];

 	/* record all known change-points (starting and ending addresses) */
 	chgidx = 0;
 	for (i=0; i < old_nr; i++)	{
 		change_point[chgidx]->addr = biosmap[i].addr;
 		change_point[chgidx++]->pbios = &biosmap[i];
 		change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
 		change_point[chgidx++]->pbios = &biosmap[i];
 	}

 	/* sort change-point list by memory addresses (low -> high) */
 	still_changing = 1;
 	while (still_changing)	{
 		still_changing = 0;
 		for (i=1; i < 2*old_nr; i++)  {
 			/* if <current_addr> > <last_addr>, swap */
 			/* or, if current=<start_addr> & last=<end_addr>, swap */
 			if ((change_point[i]->addr < change_point[i-1]->addr) ||
 				((change_point[i]->addr == change_point[i-1]->addr) &&
 				 (change_point[i]->addr == change_point[i]->pbios->addr) &&
 				 (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
 			   )
 			{
 				change_tmp = change_point[i];
 				change_point[i] = change_point[i-1];
 				change_point[i-1] = change_tmp;
 				still_changing=1;
 			}
 		}
 	}

 	/* create a new bios memory map, removing overlaps */
 	overlap_entries=0;	 /* number of entries in the overlap table */
 	new_bios_entry=0;	 /* index for creating new bios map entries */
 	last_type = 0;		 /* start with undefined memory type */
 	last_addr = 0;		 /* start with 0 as last starting address */
 	/* loop through change-points, determining affect on the new bios map */
 	for (chgidx=0; chgidx < 2*old_nr; chgidx++)
 	{
 		/* keep track of all overlapping bios entries */
 		if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
 		{
 			/* add map entry to overlap list (> 1 entry implies an overlap) */
 			overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
 		}
 		else
 		{
 			/* remove entry from list (order independent, so swap with last) */
 			for (i=0; i<overlap_entries; i++)
 			{
 				if (overlap_list[i] == change_point[chgidx]->pbios)
 					overlap_list[i] = overlap_list[overlap_entries-1];
 			}
 			overlap_entries--;
 		}
 		/* if there are overlapping entries, decide which "type" to use */
 		/* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
 		current_type = 0;
 		for (i=0; i<overlap_entries; i++)
 			if (overlap_list[i]->type > current_type)
 				current_type = overlap_list[i]->type;
 		/* continue building up new bios map based on this information */
 		if (current_type != last_type)	{
 			if (last_type != 0)	 {
 				new_bios[new_bios_entry].size =
 					change_point[chgidx]->addr - last_addr;
 				/* move forward only if the new size was non-zero */
 				if (new_bios[new_bios_entry].size != 0)
 					if (++new_bios_entry >= E820MAX)
 						break; 	/* no more space left for new bios entries */
 			}
 			if (current_type != 0)	{
 				new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
 				new_bios[new_bios_entry].type = current_type;
 				last_addr=change_point[chgidx]->addr;
 			}
 			last_type = current_type;
 		}
 	}
 	new_nr = new_bios_entry;   /* retain count for new bios entries */

 	/* copy new bios mapping into original location */
 	memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
 	*pnr_map = new_nr;

 	return 0;
 }

 /*
  * Copy the BIOS e820 map into a safe place.
  *
  * Sanity-check it while we're at it..
  *
  * If we're lucky and live on a modern system, the setup code
  * will have given us a memory map that we can use to properly
  * set up memory.  If we aren't, we'll fake a memory map.
  *
  * We check to see that the memory map contains at least 2 elements
  * before we'll use it, because the detection code in setup.S may
  * not be perfect and most every PC known to man has two memory
  * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
  * thinkpad 560x, for example, does not cooperate with the memory
  * detection code.)
  */
 static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
 {
 	/* Only one memory region (or negative)? Ignore it */
 	if (nr_map < 2)
 		return -1;

 	do {
 		unsigned long start = biosmap->addr;
 		unsigned long size = biosmap->size;
 		unsigned long end = start + size;
 		unsigned long type = biosmap->type;

 		/* Overflow in 64 bits? Ignore the memory map. */
 		if (start > end)
 			return -1;

 		/*
 		 * Some BIOSes claim RAM in the 640k - 1M region.
 		 * Not right. Fix it up.
 		 *
 		 * This should be removed on Hammer which is supposed to not
 		 * have non e820 covered ISA mappings there, but I had some strange
 		 * problems so it stays for now.  -AK
 		 */
 		if (type == E820_RAM) {
 			if (start < 0x100000ULL && end > 0xA0000ULL) {
 				if (start < 0xA0000ULL)
 					add_memory_region(start, 0xA0000ULL-start, type);
 				if (end <= 0x100000ULL)
 					continue;
 				start = 0x100000ULL;
 				size = end - start;
 			}
 		}

 		add_memory_region(start, size, type);
 	} while (biosmap++,--nr_map);
 	return 0;
 }

 void __init setup_memory_region(void)
 {
 	char *who = "BIOS-e820";

 	/*
 	 * Try to copy the BIOS-supplied E820-map.
 	 *
 	 * Otherwise fake a memory map; one section from 0k->640k,
 	 * the next section from 1mb->appropriate_mem_k
 	 */
 	sanitize_e820_map(E820_MAP, &E820_MAP_NR);
 	if (copy_e820_map(E820_MAP, E820_MAP_NR) < 0) {
 		unsigned long mem_size;

 		/* compare results from other methods and take the greater */
 		if (ALT_MEM_K < EXT_MEM_K) {
 			mem_size = EXT_MEM_K;
 			who = "BIOS-88";
 		} else {
 			mem_size = ALT_MEM_K;
 			who = "BIOS-e801";
 		}

 		e820.nr_map = 0;
 		add_memory_region(0, LOWMEMSIZE(), E820_RAM);
 		add_memory_region(HIGH_MEMORY, mem_size << 10, E820_RAM);
   	}
 	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
 	e820_print_map(who);
 }

 void __init parse_memopt(char *p, char **from)
 {
 	end_user_pfn = memparse(p, from);
 	end_user_pfn >>= PAGE_SHIFT;
 }
	/*
	* Handle the memory map.
	* The functions here do the job until bootmem takes over.
	* $Id: e820.c,v 1.4 2002/09/19 19:25:32 ak Exp $
	*/
	#include <linux/config.h>
	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <linux/init.h>
	#include <linux/bootmem.h>
	#include <linux/ioport.h>
	#include <linux/string.h>
	#include <asm/page.h>
	#include <asm/e820.h>
	#include <asm/proto.h>
	#include <asm/bootsetup.h>

	extern char _end[];

	/*
	* PFN of last memory page.
	*/
	unsigned long end_pfn;

	/*
	* end_pfn only includes RAM, while end_pfn_map includes all e820 entries.
	* The direct mapping extends to end_pfn_map, so that we can directly access
	* apertures, ACPI and other tables without having to play with fixmaps.
	*/
	unsigned long end_pfn_map;

	/*
	* Last pfn which the user wants to use.
	*/
	unsigned long end_user_pfn = MAXMEM>>PAGE_SHIFT;

	extern struct resource code_resource, data_resource;

	/* Check for some hardcoded bad areas that early boot is not allowed to touch */
	static inline int bad_addr(unsigned long *addrp, unsigned long size)
	{
	unsigned long addr = *addrp, last = addr + size;

	/* various gunk below that needed for SMP startup */
	if (addr < 0x8000) {
	*addrp = 0x8000;
	return 1;
	}

	/* direct mapping tables of the kernel */
	if (last >= table_start<<PAGE_SHIFT && addr < table_end<<PAGE_SHIFT) {
	*addrp = table_end << PAGE_SHIFT;
	return 1;
	}

	/* initrd */
	#ifdef CONFIG_BLK_DEV_INITRD
	if (LOADER_TYPE && INITRD_START && last >= INITRD_START &&
	addr < INITRD_START+INITRD_SIZE) {
	*addrp = INITRD_START + INITRD_SIZE;
	return 1;
	}
	#endif
	/* kernel code + 640k memory hole (later should not be needed, but
	be paranoid for now) */
	if (last >= 640*1024 && addr < __pa_symbol(&_end)) {
	*addrp = __pa_symbol(&_end);
	return 1;
	}
	/* XXX ramdisk image here? */
	return 0;
	}

	int __init e820_mapped(unsigned long start, unsigned long end, unsigned type)
	{
	int i;
	for (i = 0; i < e820.nr_map; i++) {
	struct e820entry *ei = &e820.map[i];
	if (type && ei->type != type)
	continue;
	if (ei->addr >= end \|\| ei->addr + ei->size < start)
	continue;
	return 1;
	}
	return 0;
	}

	/*
	* Find a free area in a specific range.
	*/
	unsigned long __init find_e820_area(unsigned long start, unsigned long end, unsigned size)
	{
	int i;
	for (i = 0; i < e820.nr_map; i++) {
	struct e820entry *ei = &e820.map[i];
	unsigned long addr = ei->addr, last;
	if (ei->type != E820_RAM)
	continue;
	if (addr < start)
	addr = start;
	if (addr > ei->addr + ei->size)
	continue;
	while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size)
	;
	last = addr + size;
	if (last > ei->addr + ei->size)
	continue;
	if (last > end)
	continue;
	return addr;
	}
	return -1UL;
	}

	/*
	* Free bootmem based on the e820 table for a node.
	*/
	void __init e820_bootmem_free(pg_data_t *pgdat, unsigned long start,unsigned long end)
	{
	int i;
	for (i = 0; i < e820.nr_map; i++) {
	struct e820entry *ei = &e820.map[i];
	unsigned long last, addr;

	if (ei->type != E820_RAM \|\|
	ei->addr+ei->size <= start \|\|
	ei->addr > end)
	continue;

	addr = round_up(ei->addr, PAGE_SIZE);
	if (addr < start)
	addr = start;

	last = round_down(ei->addr + ei->size, PAGE_SIZE);
	if (last >= end)
	last = end;

	if (last > addr && last-addr >= PAGE_SIZE)
	free_bootmem_node(pgdat, addr, last-addr);
	}
	}

	/*
	* Find the highest page frame number we have available
	*/
	unsigned long __init e820_end_of_ram(void)
	{
	int i;
	unsigned long end_pfn = 0;

	for (i = 0; i < e820.nr_map; i++) {
	struct e820entry *ei = &e820.map[i];
	unsigned long start, end;

	start = round_up(ei->addr, PAGE_SIZE);
	end = round_down(ei->addr + ei->size, PAGE_SIZE);
	if (start >= end)
	continue;
	if (ei->type == E820_RAM) {
	if (end > end_pfn<<PAGE_SHIFT)
	end_pfn = end>>PAGE_SHIFT;
	} else {
	if (end > end_pfn_map<<PAGE_SHIFT)
	end_pfn_map = end>>PAGE_SHIFT;
	}
	}

	if (end_pfn > end_pfn_map)
	end_pfn_map = end_pfn;
	if (end_pfn_map > MAXMEM>>PAGE_SHIFT)
	end_pfn_map = MAXMEM>>PAGE_SHIFT;
	if (end_pfn > end_user_pfn)
	end_pfn = end_user_pfn;
	if (end_pfn > end_pfn_map)
	end_pfn = end_pfn_map;

	return end_pfn;
	}

	/*
	* Mark e820 reserved areas as busy for the resource manager.
	*/
	void __init e820_reserve_resources(void)
	{
	int i;
	for (i = 0; i < e820.nr_map; i++) {
	struct resource *res;
	if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
	continue;
	res = alloc_bootmem_low(sizeof(struct resource));
	switch (e820.map[i].type) {
	case E820_RAM: res->name = "System RAM"; break;
	case E820_ACPI: res->name = "ACPI Tables"; break;
	case E820_NVS: res->name = "ACPI Non-volatile Storage"; break;
	default: res->name = "reserved";
	}
	res->start = e820.map[i].addr;
	res->end = res->start + e820.map[i].size - 1;
	res->flags = IORESOURCE_MEM \| IORESOURCE_BUSY;
	request_resource(&iomem_resource, res);
	if (e820.map[i].type == E820_RAM) {
	/*
	* We don't know which RAM region contains kernel data,
	* so we try it repeatedly and let the resource manager
	* test it.
	*/
	request_resource(res, &code_resource);
	request_resource(res, &data_resource);
	}
	}
	}

	/*
	* Add a memory region to the kernel e820 map.
	*/
	void __init add_memory_region(unsigned long start, unsigned long size, int type)
	{
	int x = e820.nr_map;

	if (x == E820MAX) {
	printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
	return;
	}

	e820.map[x].addr = start;
	e820.map[x].size = size;
	e820.map[x].type = type;
	e820.nr_map++;
	}

	void __init e820_print_map(char *who)
	{
	int i;

	for (i = 0; i < e820.nr_map; i++) {
	printk(" %s: %016Lx - %016Lx ", who,
	(unsigned long long) e820.map[i].addr,
	(unsigned long long) (e820.map[i].addr + e820.map[i].size));
	switch (e820.map[i].type) {
	case E820_RAM: printk("(usable)\n");
	break;
	case E820_RESERVED:
	printk("(reserved)\n");
	break;
	case E820_ACPI:
	printk("(ACPI data)\n");
	break;
	case E820_NVS:
	printk("(ACPI NVS)\n");
	break;
	default: printk("type %u\n", e820.map[i].type);
	break;
	}
	}
	}

	/*
	* Sanitize the BIOS e820 map.
	*
	* Some e820 responses include overlapping entries. The following
	* replaces the original e820 map with a new one, removing overlaps.
	*
	*/
	static int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
	{
	struct change_member {
	struct e820entry pbios; / pointer to original bios entry */
	unsigned long long addr; /* address for this change point */
	};
	static struct change_member change_point_list[2*E820MAX] __initdata;
	static struct change_member change_point[2E820MAX] __initdata;
	static struct e820entry *overlap_list[E820MAX] __initdata;
	static struct e820entry new_bios[E820MAX] __initdata;
	struct change_member *change_tmp;
	unsigned long current_type, last_type;
	unsigned long long last_addr;
	int chgidx, still_changing;
	int overlap_entries;
	int new_bios_entry;
	int old_nr, new_nr;
	int i;

	/*
	Visually we're performing the following (1,2,3,4 = memory types)...

	Sample memory map (w/overlaps):
	____22__________________
	______________________4_
	____1111________________
	_44_____________________
	11111111________________
	____________________33__
	___________44___________
	__________33333_________
	______________22________
	___________________2222_
	_________111111111______
	_____________________11_
	_________________4______

	Sanitized equivalent (no overlap):
	1_______________________
	_44_____________________
	___1____________________
	____22__________________
	______11________________
	_________1______________
	__________3_____________
	___________44___________
	_____________33_________
	_______________2________
	________________1_______
	_________________4______
	___________________2____
	____________________33__
	______________________4_
	*/

	/* if there's only one memory region, don't bother */
	if (*pnr_map < 2)
	return -1;

	old_nr = *pnr_map;

	/* bail out if we find any unreasonable addresses in bios map */
	for (i=0; i<old_nr; i++)
	if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr)
	return -1;

	/* create pointers for initial change-point information (for sorting) */
	for (i=0; i < 2*old_nr; i++)
	change_point[i] = &change_point_list[i];

	/* record all known change-points (starting and ending addresses) */
	chgidx = 0;
	for (i=0; i < old_nr; i++) {
	change_point[chgidx]->addr = biosmap[i].addr;
	change_point[chgidx++]->pbios = &biosmap[i];
	change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
	change_point[chgidx++]->pbios = &biosmap[i];
	}

	/* sort change-point list by memory addresses (low -> high) */
	still_changing = 1;
	while (still_changing) {
	still_changing = 0;
	for (i=1; i < 2*old_nr; i++) {
	/* if <current_addr> > <last_addr>, swap */
	/* or, if current=<start_addr> & last=<end_addr>, swap */
	if ((change_point[i]->addr < change_point[i-1]->addr) \|\|
	((change_point[i]->addr == change_point[i-1]->addr) &&
	(change_point[i]->addr == change_point[i]->pbios->addr) &&
	(change_point[i-1]->addr != change_point[i-1]->pbios->addr))
	)
	{
	change_tmp = change_point[i];
	change_point[i] = change_point[i-1];
	change_point[i-1] = change_tmp;
	still_changing=1;
	}
	}
	}

	/* create a new bios memory map, removing overlaps */
	overlap_entries=0; /* number of entries in the overlap table */
	new_bios_entry=0; /* index for creating new bios map entries */
	last_type = 0; /* start with undefined memory type */
	last_addr = 0; /* start with 0 as last starting address */
	/* loop through change-points, determining affect on the new bios map */
	for (chgidx=0; chgidx < 2*old_nr; chgidx++)
	{
	/* keep track of all overlapping bios entries */
	if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
	{
	/* add map entry to overlap list (> 1 entry implies an overlap) */
	overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
	}
	else
	{
	/* remove entry from list (order independent, so swap with last) */
	for (i=0; i<overlap_entries; i++)
	{
	if (overlap_list[i] == change_point[chgidx]->pbios)
	overlap_list[i] = overlap_list[overlap_entries-1];
	}
	overlap_entries--;
	}
	/* if there are overlapping entries, decide which "type" to use */
	/* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
	current_type = 0;
	for (i=0; i<overlap_entries; i++)
	if (overlap_list[i]->type > current_type)
	current_type = overlap_list[i]->type;
	/* continue building up new bios map based on this information */
	if (current_type != last_type) {
	if (last_type != 0) {
	new_bios[new_bios_entry].size =
	change_point[chgidx]->addr - last_addr;
	/* move forward only if the new size was non-zero */
	if (new_bios[new_bios_entry].size != 0)
	if (++new_bios_entry >= E820MAX)
	break; /* no more space left for new bios entries */
	}
	if (current_type != 0) {
	new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
	new_bios[new_bios_entry].type = current_type;
	last_addr=change_point[chgidx]->addr;
	}
	last_type = current_type;
	}
	}
	new_nr = new_bios_entry; /* retain count for new bios entries */

	/* copy new bios mapping into original location */
	memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
	*pnr_map = new_nr;

	return 0;
	}

	/*
	* Copy the BIOS e820 map into a safe place.
	*
	* Sanity-check it while we're at it..
	*
	* If we're lucky and live on a modern system, the setup code
	* will have given us a memory map that we can use to properly
	* set up memory. If we aren't, we'll fake a memory map.
	*
	* We check to see that the memory map contains at least 2 elements
	* before we'll use it, because the detection code in setup.S may
	* not be perfect and most every PC known to man has two memory
	* regions: one from 0 to 640k, and one from 1mb up. (The IBM
	* thinkpad 560x, for example, does not cooperate with the memory
	* detection code.)
	*/
	static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
	{
	/* Only one memory region (or negative)? Ignore it */
	if (nr_map < 2)
	return -1;

	do {
	unsigned long start = biosmap->addr;
	unsigned long size = biosmap->size;
	unsigned long end = start + size;
	unsigned long type = biosmap->type;

	/* Overflow in 64 bits? Ignore the memory map. */
	if (start > end)
	return -1;

	/*
	* Some BIOSes claim RAM in the 640k - 1M region.
	* Not right. Fix it up.
	*
	* This should be removed on Hammer which is supposed to not
	* have non e820 covered ISA mappings there, but I had some strange
	* problems so it stays for now. -AK
	*/
	if (type == E820_RAM) {
	if (start < 0x100000ULL && end > 0xA0000ULL) {
	if (start < 0xA0000ULL)
	add_memory_region(start, 0xA0000ULL-start, type);
	if (end <= 0x100000ULL)
	continue;
	start = 0x100000ULL;
	size = end - start;
	}
	}

	add_memory_region(start, size, type);
	} while (biosmap++,--nr_map);
	return 0;
	}

	void __init setup_memory_region(void)
	{
	char *who = "BIOS-e820";

	/*
	* Try to copy the BIOS-supplied E820-map.
	*
	* Otherwise fake a memory map; one section from 0k->640k,
	* the next section from 1mb->appropriate_mem_k
	*/
	sanitize_e820_map(E820_MAP, &E820_MAP_NR);
	if (copy_e820_map(E820_MAP, E820_MAP_NR) < 0) {
	unsigned long mem_size;

	/* compare results from other methods and take the greater */
	if (ALT_MEM_K < EXT_MEM_K) {
	mem_size = EXT_MEM_K;
	who = "BIOS-88";
	} else {
	mem_size = ALT_MEM_K;
	who = "BIOS-e801";
	}

	e820.nr_map = 0;
	add_memory_region(0, LOWMEMSIZE(), E820_RAM);
	add_memory_region(HIGH_MEMORY, mem_size << 10, E820_RAM);
	}
	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
	e820_print_map(who);
	}

	void __init parse_memopt(char p, char *from)
	{
	end_user_pfn = memparse(p, from);
	end_user_pfn >>= PAGE_SHIFT;
	}