arch/unicore32/mm/init.c - kernel/quantenna - Git at Google

 /*
  *  linux/arch/unicore32/mm/init.c
  *
  *  Copyright (C) 2010 GUAN Xue-tao
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/swap.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
 #include <linux/highmem.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/sort.h>
 #include <linux/dma-mapping.h>
 #include <linux/export.h>

 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/sizes.h>
 #include <asm/tlb.h>
 #include <asm/memblock.h>
 #include <mach/map.h>

 #include "mm.h"

 static unsigned long phys_initrd_start __initdata = 0x01000000;
 static unsigned long phys_initrd_size __initdata = SZ_8M;

 static int __init early_initrd(char *p)
 {
 	unsigned long start, size;
 	char *endp;

 	start = memparse(p, &endp);
 	if (*endp == ',') {
 		size = memparse(endp + 1, NULL);

 		phys_initrd_start = start;
 		phys_initrd_size = size;
 	}
 	return 0;
 }
 early_param("initrd", early_initrd);

 /*
  * This keeps memory configuration data used by a couple memory
  * initialization functions, as well as show_mem() for the skipping
  * of holes in the memory map.  It is populated by uc32_add_memory().
  */
 struct meminfo meminfo;

 void show_mem(unsigned int filter)
 {
 	int free = 0, total = 0, reserved = 0;
 	int shared = 0, cached = 0, slab = 0, i;
 	struct meminfo *mi = &meminfo;

 	printk(KERN_DEFAULT "Mem-info:\n");
 	show_free_areas(filter);

 	for_each_bank(i, mi) {
 		struct membank *bank = &mi->bank[i];
 		unsigned int pfn1, pfn2;
 		struct page *page, *end;

 		pfn1 = bank_pfn_start(bank);
 		pfn2 = bank_pfn_end(bank);

 		page = pfn_to_page(pfn1);
 		end  = pfn_to_page(pfn2 - 1) + 1;

 		do {
 			total++;
 			if (PageReserved(page))
 				reserved++;
 			else if (PageSwapCache(page))
 				cached++;
 			else if (PageSlab(page))
 				slab++;
 			else if (!page_count(page))
 				free++;
 			else
 				shared += page_count(page) - 1;
 			page++;
 		} while (page < end);
 	}

 	printk(KERN_DEFAULT "%d pages of RAM\n", total);
 	printk(KERN_DEFAULT "%d free pages\n", free);
 	printk(KERN_DEFAULT "%d reserved pages\n", reserved);
 	printk(KERN_DEFAULT "%d slab pages\n", slab);
 	printk(KERN_DEFAULT "%d pages shared\n", shared);
 	printk(KERN_DEFAULT "%d pages swap cached\n", cached);
 }

 static void __init find_limits(unsigned long *min, unsigned long *max_low,
 	unsigned long *max_high)
 {
 	struct meminfo *mi = &meminfo;
 	int i;

 	*min = -1UL;
 	*max_low = *max_high = 0;

 	for_each_bank(i, mi) {
 		struct membank *bank = &mi->bank[i];
 		unsigned long start, end;

 		start = bank_pfn_start(bank);
 		end = bank_pfn_end(bank);

 		if (*min > start)
 			*min = start;
 		if (*max_high < end)
 			*max_high = end;
 		if (bank->highmem)
 			continue;
 		if (*max_low < end)
 			*max_low = end;
 	}
 }

 static void __init uc32_bootmem_init(unsigned long start_pfn,
 	unsigned long end_pfn)
 {
 	struct memblock_region *reg;
 	unsigned int boot_pages;
 	phys_addr_t bitmap;
 	pg_data_t *pgdat;

 	/*
 	 * Allocate the bootmem bitmap page.  This must be in a region
 	 * of memory which has already been mapped.
 	 */
 	boot_pages = bootmem_bootmap_pages(end_pfn - start_pfn);
 	bitmap = memblock_alloc_base(boot_pages << PAGE_SHIFT, L1_CACHE_BYTES,
 				__pfn_to_phys(end_pfn));

 	/*
 	 * Initialise the bootmem allocator, handing the
 	 * memory banks over to bootmem.
 	 */
 	node_set_online(0);
 	pgdat = NODE_DATA(0);
 	init_bootmem_node(pgdat, __phys_to_pfn(bitmap), start_pfn, end_pfn);

 	/* Free the lowmem regions from memblock into bootmem. */
 	for_each_memblock(memory, reg) {
 		unsigned long start = memblock_region_memory_base_pfn(reg);
 		unsigned long end = memblock_region_memory_end_pfn(reg);

 		if (end >= end_pfn)
 			end = end_pfn;
 		if (start >= end)
 			break;

 		free_bootmem(__pfn_to_phys(start), (end - start) << PAGE_SHIFT);
 	}

 	/* Reserve the lowmem memblock reserved regions in bootmem. */
 	for_each_memblock(reserved, reg) {
 		unsigned long start = memblock_region_reserved_base_pfn(reg);
 		unsigned long end = memblock_region_reserved_end_pfn(reg);

 		if (end >= end_pfn)
 			end = end_pfn;
 		if (start >= end)
 			break;

 		reserve_bootmem(__pfn_to_phys(start),
 			(end - start) << PAGE_SHIFT, BOOTMEM_DEFAULT);
 	}
 }

 static void __init uc32_bootmem_free(unsigned long min, unsigned long max_low,
 	unsigned long max_high)
 {
 	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
 	struct memblock_region *reg;

 	/*
 	 * initialise the zones.
 	 */
 	memset(zone_size, 0, sizeof(zone_size));

 	/*
 	 * The memory size has already been determined.  If we need
 	 * to do anything fancy with the allocation of this memory
 	 * to the zones, now is the time to do it.
 	 */
 	zone_size[0] = max_low - min;

 	/*
 	 * Calculate the size of the holes.
 	 *  holes = node_size - sum(bank_sizes)
 	 */
 	memcpy(zhole_size, zone_size, sizeof(zhole_size));
 	for_each_memblock(memory, reg) {
 		unsigned long start = memblock_region_memory_base_pfn(reg);
 		unsigned long end = memblock_region_memory_end_pfn(reg);

 		if (start < max_low) {
 			unsigned long low_end = min(end, max_low);
 			zhole_size[0] -= low_end - start;
 		}
 	}

 	/*
 	 * Adjust the sizes according to any special requirements for
 	 * this machine type.
 	 */
 	arch_adjust_zones(zone_size, zhole_size);

 	free_area_init_node(0, zone_size, min, zhole_size);
 }

 int pfn_valid(unsigned long pfn)
 {
 	return memblock_is_memory(pfn << PAGE_SHIFT);
 }
 EXPORT_SYMBOL(pfn_valid);

 static void uc32_memory_present(void)
 {
 }

 static int __init meminfo_cmp(const void *_a, const void *_b)
 {
 	const struct membank *a = _a, *b = _b;
 	long cmp = bank_pfn_start(a) - bank_pfn_start(b);
 	return cmp < 0 ? -1 : cmp > 0 ? 1 : 0;
 }

 void __init uc32_memblock_init(struct meminfo *mi)
 {
 	int i;

 	sort(&meminfo.bank, meminfo.nr_banks, sizeof(meminfo.bank[0]),
 		meminfo_cmp, NULL);

 	for (i = 0; i < mi->nr_banks; i++)
 		memblock_add(mi->bank[i].start, mi->bank[i].size);

 	/* Register the kernel text, kernel data and initrd with memblock. */
 	memblock_reserve(__pa(_text), _end - _text);

 #ifdef CONFIG_BLK_DEV_INITRD
 	if (phys_initrd_size) {
 		memblock_reserve(phys_initrd_start, phys_initrd_size);

 		/* Now convert initrd to virtual addresses */
 		initrd_start = __phys_to_virt(phys_initrd_start);
 		initrd_end = initrd_start + phys_initrd_size;
 	}
 #endif

 	uc32_mm_memblock_reserve();

 	memblock_allow_resize();
 	memblock_dump_all();
 }

 void __init bootmem_init(void)
 {
 	unsigned long min, max_low, max_high;

 	max_low = max_high = 0;

 	find_limits(&min, &max_low, &max_high);

 	uc32_bootmem_init(min, max_low);

 #ifdef CONFIG_SWIOTLB
 	swiotlb_init(1);
 #endif
 	/*
 	 * Sparsemem tries to allocate bootmem in memory_present(),
 	 * so must be done after the fixed reservations
 	 */
 	uc32_memory_present();

 	/*
 	 * sparse_init() needs the bootmem allocator up and running.
 	 */
 	sparse_init();

 	/*
 	 * Now free the memory - free_area_init_node needs
 	 * the sparse mem_map arrays initialized by sparse_init()
 	 * for memmap_init_zone(), otherwise all PFNs are invalid.
 	 */
 	uc32_bootmem_free(min, max_low, max_high);

 	high_memory = __va((max_low << PAGE_SHIFT) - 1) + 1;

 	/*
 	 * This doesn't seem to be used by the Linux memory manager any
 	 * more, but is used by ll_rw_block.  If we can get rid of it, we
 	 * also get rid of some of the stuff above as well.
 	 *
 	 * Note: max_low_pfn and max_pfn reflect the number of _pages_ in
 	 * the system, not the maximum PFN.
 	 */
 	max_low_pfn = max_low - PHYS_PFN_OFFSET;
 	max_pfn = max_high - PHYS_PFN_OFFSET;
 }

 static inline void
 free_memmap(unsigned long start_pfn, unsigned long end_pfn)
 {
 	struct page *start_pg, *end_pg;
 	unsigned long pg, pgend;

 	/*
 	 * Convert start_pfn/end_pfn to a struct page pointer.
 	 */
 	start_pg = pfn_to_page(start_pfn - 1) + 1;
 	end_pg = pfn_to_page(end_pfn);

 	/*
 	 * Convert to physical addresses, and
 	 * round start upwards and end downwards.
 	 */
 	pg = PAGE_ALIGN(__pa(start_pg));
 	pgend = __pa(end_pg) & PAGE_MASK;

 	/*
 	 * If there are free pages between these,
 	 * free the section of the memmap array.
 	 */
 	if (pg < pgend)
 		free_bootmem(pg, pgend - pg);
 }

 /*
  * The mem_map array can get very big.  Free the unused area of the memory map.
  */
 static void __init free_unused_memmap(struct meminfo *mi)
 {
 	unsigned long bank_start, prev_bank_end = 0;
 	unsigned int i;

 	/*
 	 * This relies on each bank being in address order.
 	 * The banks are sorted previously in bootmem_init().
 	 */
 	for_each_bank(i, mi) {
 		struct membank *bank = &mi->bank[i];

 		bank_start = bank_pfn_start(bank);

 		/*
 		 * If we had a previous bank, and there is a space
 		 * between the current bank and the previous, free it.
 		 */
 		if (prev_bank_end && prev_bank_end < bank_start)
 			free_memmap(prev_bank_end, bank_start);

 		/*
 		 * Align up here since the VM subsystem insists that the
 		 * memmap entries are valid from the bank end aligned to
 		 * MAX_ORDER_NR_PAGES.
 		 */
 		prev_bank_end = ALIGN(bank_pfn_end(bank), MAX_ORDER_NR_PAGES);
 	}
 }

 /*
  * mem_init() marks the free areas in the mem_map and tells us how much
  * memory is free.  This is done after various parts of the system have
  * claimed their memory after the kernel image.
  */
 void __init mem_init(void)
 {
 	max_mapnr   = pfn_to_page(max_pfn + PHYS_PFN_OFFSET) - mem_map;

 	free_unused_memmap(&meminfo);

 	/* this will put all unused low memory onto the freelists */
 	free_all_bootmem();

 	mem_init_print_info(NULL);
 	printk(KERN_NOTICE "Virtual kernel memory layout:\n"
 		"    vector  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
 		"    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 		"    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 		"    modules : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 		"      .init : 0x%p" " - 0x%p" "   (%4d kB)\n"
 		"      .text : 0x%p" " - 0x%p" "   (%4d kB)\n"
 		"      .data : 0x%p" " - 0x%p" "   (%4d kB)\n",

 		VECTORS_BASE, VECTORS_BASE + PAGE_SIZE,
 		DIV_ROUND_UP(PAGE_SIZE, SZ_1K),
 		VMALLOC_START, VMALLOC_END,
 		DIV_ROUND_UP((VMALLOC_END - VMALLOC_START), SZ_1M),
 		PAGE_OFFSET, (unsigned long)high_memory,
 		DIV_ROUND_UP(((unsigned long)high_memory - PAGE_OFFSET), SZ_1M),
 		MODULES_VADDR, MODULES_END,
 		DIV_ROUND_UP((MODULES_END - MODULES_VADDR), SZ_1M),

 		__init_begin, __init_end,
 		DIV_ROUND_UP((__init_end - __init_begin), SZ_1K),
 		_stext, _etext,
 		DIV_ROUND_UP((_etext - _stext), SZ_1K),
 		_sdata, _edata,
 		DIV_ROUND_UP((_edata - _sdata), SZ_1K));

 	BUILD_BUG_ON(TASK_SIZE				> MODULES_VADDR);
 	BUG_ON(TASK_SIZE				> MODULES_VADDR);

 	if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
 		/*
 		 * On a machine this small we won't get
 		 * anywhere without overcommit, so turn
 		 * it on by default.
 		 */
 		sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
 	}
 }

 void free_initmem(void)
 {
 	free_initmem_default(-1);
 }

 #ifdef CONFIG_BLK_DEV_INITRD

 static int keep_initrd;

 void free_initrd_mem(unsigned long start, unsigned long end)
 {
 	if (!keep_initrd)
 		free_reserved_area((void *)start, (void *)end, -1, "initrd");
 }

 static int __init keepinitrd_setup(char *__unused)
 {
 	keep_initrd = 1;
 	return 1;
 }

 __setup("keepinitrd", keepinitrd_setup);
 #endif
	/*
	* linux/arch/unicore32/mm/init.c
	*
	* Copyright (C) 2010 GUAN Xue-tao
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/swap.h>
	#include <linux/init.h>
	#include <linux/bootmem.h>
	#include <linux/mman.h>
	#include <linux/nodemask.h>
	#include <linux/initrd.h>
	#include <linux/highmem.h>
	#include <linux/gfp.h>
	#include <linux/memblock.h>
	#include <linux/sort.h>
	#include <linux/dma-mapping.h>
	#include <linux/export.h>

	#include <asm/sections.h>
	#include <asm/setup.h>
	#include <asm/sizes.h>
	#include <asm/tlb.h>
	#include <asm/memblock.h>
	#include <mach/map.h>

	#include "mm.h"

	static unsigned long phys_initrd_start __initdata = 0x01000000;
	static unsigned long phys_initrd_size __initdata = SZ_8M;

	static int __init early_initrd(char *p)
	{
	unsigned long start, size;
	char *endp;

	start = memparse(p, &endp);
	if (*endp == ',') {
	size = memparse(endp + 1, NULL);

	phys_initrd_start = start;
	phys_initrd_size = size;
	}
	return 0;
	}
	early_param("initrd", early_initrd);

	/*
	* This keeps memory configuration data used by a couple memory
	* initialization functions, as well as show_mem() for the skipping
	* of holes in the memory map. It is populated by uc32_add_memory().
	*/
	struct meminfo meminfo;

	void show_mem(unsigned int filter)
	{
	int free = 0, total = 0, reserved = 0;
	int shared = 0, cached = 0, slab = 0, i;
	struct meminfo *mi = &meminfo;

	printk(KERN_DEFAULT "Mem-info:\n");
	show_free_areas(filter);

	for_each_bank(i, mi) {
	struct membank *bank = &mi->bank[i];
	unsigned int pfn1, pfn2;
	struct page page, end;

	pfn1 = bank_pfn_start(bank);
	pfn2 = bank_pfn_end(bank);

	page = pfn_to_page(pfn1);
	end = pfn_to_page(pfn2 - 1) + 1;

	do {
	total++;
	if (PageReserved(page))
	reserved++;
	else if (PageSwapCache(page))
	cached++;
	else if (PageSlab(page))
	slab++;
	else if (!page_count(page))
	free++;
	else
	shared += page_count(page) - 1;
	page++;
	} while (page < end);
	}

	printk(KERN_DEFAULT "%d pages of RAM\n", total);
	printk(KERN_DEFAULT "%d free pages\n", free);
	printk(KERN_DEFAULT "%d reserved pages\n", reserved);
	printk(KERN_DEFAULT "%d slab pages\n", slab);
	printk(KERN_DEFAULT "%d pages shared\n", shared);
	printk(KERN_DEFAULT "%d pages swap cached\n", cached);
	}

	static void __init find_limits(unsigned long min, unsigned long max_low,
	unsigned long *max_high)
	{
	struct meminfo *mi = &meminfo;
	int i;

	*min = -1UL;
	max_low = max_high = 0;

	for_each_bank(i, mi) {
	struct membank *bank = &mi->bank[i];
	unsigned long start, end;

	start = bank_pfn_start(bank);
	end = bank_pfn_end(bank);

	if (*min > start)
	*min = start;
	if (*max_high < end)
	*max_high = end;
	if (bank->highmem)
	continue;
	if (*max_low < end)
	*max_low = end;
	}
	}

	static void __init uc32_bootmem_init(unsigned long start_pfn,
	unsigned long end_pfn)
	{
	struct memblock_region *reg;
	unsigned int boot_pages;
	phys_addr_t bitmap;
	pg_data_t *pgdat;

	/*
	* Allocate the bootmem bitmap page. This must be in a region
	* of memory which has already been mapped.
	*/
	boot_pages = bootmem_bootmap_pages(end_pfn - start_pfn);
	bitmap = memblock_alloc_base(boot_pages << PAGE_SHIFT, L1_CACHE_BYTES,
	__pfn_to_phys(end_pfn));

	/*
	* Initialise the bootmem allocator, handing the
	* memory banks over to bootmem.
	*/
	node_set_online(0);
	pgdat = NODE_DATA(0);
	init_bootmem_node(pgdat, __phys_to_pfn(bitmap), start_pfn, end_pfn);

	/* Free the lowmem regions from memblock into bootmem. */
	for_each_memblock(memory, reg) {
	unsigned long start = memblock_region_memory_base_pfn(reg);
	unsigned long end = memblock_region_memory_end_pfn(reg);

	if (end >= end_pfn)
	end = end_pfn;
	if (start >= end)
	break;

	free_bootmem(__pfn_to_phys(start), (end - start) << PAGE_SHIFT);
	}

	/* Reserve the lowmem memblock reserved regions in bootmem. */
	for_each_memblock(reserved, reg) {
	unsigned long start = memblock_region_reserved_base_pfn(reg);
	unsigned long end = memblock_region_reserved_end_pfn(reg);

	if (end >= end_pfn)
	end = end_pfn;
	if (start >= end)
	break;

	reserve_bootmem(__pfn_to_phys(start),
	(end - start) << PAGE_SHIFT, BOOTMEM_DEFAULT);
	}
	}

	static void __init uc32_bootmem_free(unsigned long min, unsigned long max_low,
	unsigned long max_high)
	{
	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
	struct memblock_region *reg;

	/*
	* initialise the zones.
	*/
	memset(zone_size, 0, sizeof(zone_size));

	/*
	* The memory size has already been determined. If we need
	* to do anything fancy with the allocation of this memory
	* to the zones, now is the time to do it.
	*/
	zone_size[0] = max_low - min;

	/*
	* Calculate the size of the holes.
	* holes = node_size - sum(bank_sizes)
	*/
	memcpy(zhole_size, zone_size, sizeof(zhole_size));
	for_each_memblock(memory, reg) {
	unsigned long start = memblock_region_memory_base_pfn(reg);
	unsigned long end = memblock_region_memory_end_pfn(reg);

	if (start < max_low) {
	unsigned long low_end = min(end, max_low);
	zhole_size[0] -= low_end - start;
	}
	}

	/*
	* Adjust the sizes according to any special requirements for
	* this machine type.
	*/
	arch_adjust_zones(zone_size, zhole_size);

	free_area_init_node(0, zone_size, min, zhole_size);
	}

	int pfn_valid(unsigned long pfn)
	{
	return memblock_is_memory(pfn << PAGE_SHIFT);
	}
	EXPORT_SYMBOL(pfn_valid);

	static void uc32_memory_present(void)
	{
	}

	static int __init meminfo_cmp(const void _a, const void _b)
	{
	const struct membank a = _a, b = _b;
	long cmp = bank_pfn_start(a) - bank_pfn_start(b);
	return cmp < 0 ? -1 : cmp > 0 ? 1 : 0;
	}

	void __init uc32_memblock_init(struct meminfo *mi)
	{
	int i;

	sort(&meminfo.bank, meminfo.nr_banks, sizeof(meminfo.bank[0]),
	meminfo_cmp, NULL);

	for (i = 0; i < mi->nr_banks; i++)
	memblock_add(mi->bank[i].start, mi->bank[i].size);

	/* Register the kernel text, kernel data and initrd with memblock. */
	memblock_reserve(__pa(_text), _end - _text);

	#ifdef CONFIG_BLK_DEV_INITRD
	if (phys_initrd_size) {
	memblock_reserve(phys_initrd_start, phys_initrd_size);

	/* Now convert initrd to virtual addresses */
	initrd_start = __phys_to_virt(phys_initrd_start);
	initrd_end = initrd_start + phys_initrd_size;
	}
	#endif

	uc32_mm_memblock_reserve();

	memblock_allow_resize();
	memblock_dump_all();
	}

	void __init bootmem_init(void)
	{
	unsigned long min, max_low, max_high;

	max_low = max_high = 0;

	find_limits(&min, &max_low, &max_high);

	uc32_bootmem_init(min, max_low);

	#ifdef CONFIG_SWIOTLB
	swiotlb_init(1);
	#endif
	/*
	* Sparsemem tries to allocate bootmem in memory_present(),
	* so must be done after the fixed reservations
	*/
	uc32_memory_present();

	/*
	* sparse_init() needs the bootmem allocator up and running.
	*/
	sparse_init();

	/*
	* Now free the memory - free_area_init_node needs
	* the sparse mem_map arrays initialized by sparse_init()
	* for memmap_init_zone(), otherwise all PFNs are invalid.
	*/
	uc32_bootmem_free(min, max_low, max_high);

	high_memory = __va((max_low << PAGE_SHIFT) - 1) + 1;

	/*
	* This doesn't seem to be used by the Linux memory manager any
	* more, but is used by ll_rw_block. If we can get rid of it, we
	* also get rid of some of the stuff above as well.
	*
	* Note: max_low_pfn and max_pfn reflect the number of _pages_ in
	* the system, not the maximum PFN.
	*/
	max_low_pfn = max_low - PHYS_PFN_OFFSET;
	max_pfn = max_high - PHYS_PFN_OFFSET;
	}

	static inline void
	free_memmap(unsigned long start_pfn, unsigned long end_pfn)
	{
	struct page start_pg, end_pg;
	unsigned long pg, pgend;

	/*
	* Convert start_pfn/end_pfn to a struct page pointer.
	*/
	start_pg = pfn_to_page(start_pfn - 1) + 1;
	end_pg = pfn_to_page(end_pfn);

	/*
	* Convert to physical addresses, and
	* round start upwards and end downwards.
	*/
	pg = PAGE_ALIGN(__pa(start_pg));
	pgend = __pa(end_pg) & PAGE_MASK;

	/*
	* If there are free pages between these,
	* free the section of the memmap array.
	*/
	if (pg < pgend)
	free_bootmem(pg, pgend - pg);
	}

	/*
	* The mem_map array can get very big. Free the unused area of the memory map.
	*/
	static void __init free_unused_memmap(struct meminfo *mi)
	{
	unsigned long bank_start, prev_bank_end = 0;
	unsigned int i;

	/*
	* This relies on each bank being in address order.
	* The banks are sorted previously in bootmem_init().
	*/
	for_each_bank(i, mi) {
	struct membank *bank = &mi->bank[i];

	bank_start = bank_pfn_start(bank);

	/*
	* If we had a previous bank, and there is a space
	* between the current bank and the previous, free it.
	*/
	if (prev_bank_end && prev_bank_end < bank_start)
	free_memmap(prev_bank_end, bank_start);

	/*
	* Align up here since the VM subsystem insists that the
	* memmap entries are valid from the bank end aligned to
	* MAX_ORDER_NR_PAGES.
	*/
	prev_bank_end = ALIGN(bank_pfn_end(bank), MAX_ORDER_NR_PAGES);
	}
	}

	/*
	* mem_init() marks the free areas in the mem_map and tells us how much
	* memory is free. This is done after various parts of the system have
	* claimed their memory after the kernel image.
	*/
	void __init mem_init(void)
	{
	max_mapnr = pfn_to_page(max_pfn + PHYS_PFN_OFFSET) - mem_map;

	free_unused_memmap(&meminfo);

	/* this will put all unused low memory onto the freelists */
	free_all_bootmem();

	mem_init_print_info(NULL);
	printk(KERN_NOTICE "Virtual kernel memory layout:\n"
	" vector : 0x%08lx - 0x%08lx (%4ld kB)\n"
	" vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n"
	" lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n"
	" modules : 0x%08lx - 0x%08lx (%4ld MB)\n"
	" .init : 0x%p" " - 0x%p" " (%4d kB)\n"
	" .text : 0x%p" " - 0x%p" " (%4d kB)\n"
	" .data : 0x%p" " - 0x%p" " (%4d kB)\n",

	VECTORS_BASE, VECTORS_BASE + PAGE_SIZE,
	DIV_ROUND_UP(PAGE_SIZE, SZ_1K),
	VMALLOC_START, VMALLOC_END,
	DIV_ROUND_UP((VMALLOC_END - VMALLOC_START), SZ_1M),
	PAGE_OFFSET, (unsigned long)high_memory,
	DIV_ROUND_UP(((unsigned long)high_memory - PAGE_OFFSET), SZ_1M),
	MODULES_VADDR, MODULES_END,
	DIV_ROUND_UP((MODULES_END - MODULES_VADDR), SZ_1M),

	__init_begin, __init_end,
	DIV_ROUND_UP((__init_end - __init_begin), SZ_1K),
	_stext, _etext,
	DIV_ROUND_UP((_etext - _stext), SZ_1K),
	_sdata, _edata,
	DIV_ROUND_UP((_edata - _sdata), SZ_1K));

	BUILD_BUG_ON(TASK_SIZE > MODULES_VADDR);
	BUG_ON(TASK_SIZE > MODULES_VADDR);

	if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
	/*
	* On a machine this small we won't get
	* anywhere without overcommit, so turn
	* it on by default.
	*/
	sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
	}
	}

	void free_initmem(void)
	{
	free_initmem_default(-1);
	}

	#ifdef CONFIG_BLK_DEV_INITRD

	static int keep_initrd;

	void free_initrd_mem(unsigned long start, unsigned long end)
	{
	if (!keep_initrd)
	free_reserved_area((void )start, (void )end, -1, "initrd");
	}

	static int __init keepinitrd_setup(char *__unused)
	{
	keep_initrd = 1;
	return 1;
	}

	__setup("keepinitrd", keepinitrd_setup);
	#endif