arch/xtensa/mm/init.c - kernel/lockdown - Git at Google

 /*
  * arch/xtensa/mm/init.c
  *
  * Derived from MIPS, PPC.
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
  * Copyright (C) 2001 - 2005 Tensilica Inc.
  * Copyright (C) 2014 Cadence Design Systems Inc.
  *
  * Chris Zankel	<chris@zankel.net>
  * Joe Taylor	<joe@tensilica.com, joetylr@yahoo.com>
  * Marc Gauthier
  * Kevin Chea
  */

 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/bootmem.h>
 #include <linux/gfp.h>
 #include <linux/highmem.h>
 #include <linux/swap.h>
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/mm.h>

 #include <asm/bootparam.h>
 #include <asm/page.h>
 #include <asm/sections.h>
 #include <asm/sysmem.h>

 struct sysmem_info sysmem __initdata;

 static void __init sysmem_dump(void)
 {
 	unsigned i;

 	pr_debug("Sysmem:\n");
 	for (i = 0; i < sysmem.nr_banks; ++i)
 		pr_debug("  0x%08lx - 0x%08lx (%ldK)\n",
 			 sysmem.bank[i].start, sysmem.bank[i].end,
 			 (sysmem.bank[i].end - sysmem.bank[i].start) >> 10);
 }

 /*
  * Find bank with maximal .start such that bank.start <= start
  */
 static inline struct meminfo * __init find_bank(unsigned long start)
 {
 	unsigned i;
 	struct meminfo *it = NULL;

 	for (i = 0; i < sysmem.nr_banks; ++i)
 		if (sysmem.bank[i].start <= start)
 			it = sysmem.bank + i;
 		else
 			break;
 	return it;
 }

 /*
  * Move all memory banks starting at 'from' to a new place at 'to',
  * adjust nr_banks accordingly.
  * Both 'from' and 'to' must be inside the sysmem.bank.
  *
  * Returns: 0 (success), -ENOMEM (not enough space in the sysmem.bank).
  */
 static int __init move_banks(struct meminfo *to, struct meminfo *from)
 {
 	unsigned n = sysmem.nr_banks - (from - sysmem.bank);

 	if (to > from && to - from + sysmem.nr_banks > SYSMEM_BANKS_MAX)
 		return -ENOMEM;
 	if (to != from)
 		memmove(to, from, n * sizeof(struct meminfo));
 	sysmem.nr_banks += to - from;
 	return 0;
 }

 /*
  * Add new bank to sysmem. Resulting sysmem is the union of bytes of the
  * original sysmem and the new bank.
  *
  * Returns: 0 (success), < 0 (error)
  */
 int __init add_sysmem_bank(unsigned long start, unsigned long end)
 {
 	unsigned i;
 	struct meminfo *it = NULL;
 	unsigned long sz;
 	unsigned long bank_sz = 0;

 	if (start == end ||
 	    (start < end) != (PAGE_ALIGN(start) < (end & PAGE_MASK))) {
 		pr_warn("Ignoring small memory bank 0x%08lx size: %ld bytes\n",
 			start, end - start);
 		return -EINVAL;
 	}

 	start = PAGE_ALIGN(start);
 	end &= PAGE_MASK;
 	sz = end - start;

 	it = find_bank(start);

 	if (it)
 		bank_sz = it->end - it->start;

 	if (it && bank_sz >= start - it->start) {
 		if (end - it->start > bank_sz)
 			it->end = end;
 		else
 			return 0;
 	} else {
 		if (!it)
 			it = sysmem.bank;
 		else
 			++it;

 		if (it - sysmem.bank < sysmem.nr_banks &&
 		    it->start - start <= sz) {
 			it->start = start;
 			if (it->end - it->start < sz)
 				it->end = end;
 			else
 				return 0;
 		} else {
 			if (move_banks(it + 1, it) < 0) {
 				pr_warn("Ignoring memory bank 0x%08lx size %ld bytes\n",
 					start, end - start);
 				return -EINVAL;
 			}
 			it->start = start;
 			it->end = end;
 			return 0;
 		}
 	}
 	sz = it->end - it->start;
 	for (i = it + 1 - sysmem.bank; i < sysmem.nr_banks; ++i)
 		if (sysmem.bank[i].start - it->start <= sz) {
 			if (sz < sysmem.bank[i].end - it->start)
 				it->end = sysmem.bank[i].end;
 		} else {
 			break;
 		}

 	move_banks(it + 1, sysmem.bank + i);
 	return 0;
 }

 /*
  * mem_reserve(start, end, must_exist)
  *
  * Reserve some memory from the memory pool.
  * If must_exist is set and a part of the region being reserved does not exist
  * memory map is not altered.
  *
  * Parameters:
  *  start	Start of region,
  *  end		End of region,
  *  must_exist	Must exist in memory pool.
  *
  * Returns:
  *  0 (success)
  *  < 0 (error)
  */

 int __init mem_reserve(unsigned long start, unsigned long end, int must_exist)
 {
 	struct meminfo *it;
 	struct meminfo *rm = NULL;
 	unsigned long sz;
 	unsigned long bank_sz = 0;

 	start = start & PAGE_MASK;
 	end = PAGE_ALIGN(end);
 	sz = end - start;
 	if (!sz)
 		return -EINVAL;

 	it = find_bank(start);

 	if (it)
 		bank_sz = it->end - it->start;

 	if ((!it || end - it->start > bank_sz) && must_exist) {
 		pr_warn("mem_reserve: [0x%0lx, 0x%0lx) not in any region!\n",
 			start, end);
 		return -EINVAL;
 	}

 	if (it && start - it->start <= bank_sz) {
 		if (start == it->start) {
 			if (end - it->start < bank_sz) {
 				it->start = end;
 				return 0;
 			} else {
 				rm = it;
 			}
 		} else {
 			it->end = start;
 			if (end - it->start < bank_sz)
 				return add_sysmem_bank(end,
 						       it->start + bank_sz);
 			++it;
 		}
 	}

 	if (!it)
 		it = sysmem.bank;

 	for (; it < sysmem.bank + sysmem.nr_banks; ++it) {
 		if (it->end - start <= sz) {
 			if (!rm)
 				rm = it;
 		} else {
 			if (it->start - start < sz)
 				it->start = end;
 			break;
 		}
 	}

 	if (rm)
 		move_banks(rm, it);

 	return 0;
 }


 /*
  * Initialize the bootmem system and give it all low memory we have available.
  */

 void __init bootmem_init(void)
 {
 	unsigned long pfn;
 	unsigned long bootmap_start, bootmap_size;
 	int i;

 	/* Reserve all memory below PLATFORM_DEFAULT_MEM_START, as memory
 	 * accounting doesn't work for pages below that address.
 	 *
 	 * If PLATFORM_DEFAULT_MEM_START is zero reserve page at address 0:
 	 * successfull allocations should never return NULL.
 	 */
 	if (PLATFORM_DEFAULT_MEM_START)
 		mem_reserve(0, PLATFORM_DEFAULT_MEM_START, 0);
 	else
 		mem_reserve(0, 1, 0);

 	sysmem_dump();
 	max_low_pfn = max_pfn = 0;
 	min_low_pfn = ~0;

 	for (i=0; i < sysmem.nr_banks; i++) {
 		pfn = PAGE_ALIGN(sysmem.bank[i].start) >> PAGE_SHIFT;
 		if (pfn < min_low_pfn)
 			min_low_pfn = pfn;
 		pfn = PAGE_ALIGN(sysmem.bank[i].end - 1) >> PAGE_SHIFT;
 		if (pfn > max_pfn)
 			max_pfn = pfn;
 	}

 	if (min_low_pfn > max_pfn)
 		panic("No memory found!\n");

 	max_low_pfn = max_pfn < MAX_MEM_PFN >> PAGE_SHIFT ?
 		max_pfn : MAX_MEM_PFN >> PAGE_SHIFT;

 	/* Find an area to use for the bootmem bitmap. */

 	bootmap_size = bootmem_bootmap_pages(max_low_pfn - min_low_pfn);
 	bootmap_size <<= PAGE_SHIFT;
 	bootmap_start = ~0;

 	for (i=0; i<sysmem.nr_banks; i++)
 		if (sysmem.bank[i].end - sysmem.bank[i].start >= bootmap_size) {
 			bootmap_start = sysmem.bank[i].start;
 			break;
 		}

 	if (bootmap_start == ~0UL)
 		panic("Cannot find %ld bytes for bootmap\n", bootmap_size);

 	/* Reserve the bootmem bitmap area */

 	mem_reserve(bootmap_start, bootmap_start + bootmap_size, 1);
 	bootmap_size = init_bootmem_node(NODE_DATA(0),
 					 bootmap_start >> PAGE_SHIFT,
 					 min_low_pfn,
 					 max_low_pfn);

 	/* Add all remaining memory pieces into the bootmem map */

 	for (i = 0; i < sysmem.nr_banks; i++) {
 		if (sysmem.bank[i].start >> PAGE_SHIFT < max_low_pfn) {
 			unsigned long end = min(max_low_pfn << PAGE_SHIFT,
 						sysmem.bank[i].end);
 			free_bootmem(sysmem.bank[i].start,
 				     end - sysmem.bank[i].start);
 		}
 	}

 }


 void __init zones_init(void)
 {
 	/* All pages are DMA-able, so we put them all in the DMA zone. */
 	unsigned long zones_size[MAX_NR_ZONES] = {
 		[ZONE_DMA] = max_low_pfn - ARCH_PFN_OFFSET,
 #ifdef CONFIG_HIGHMEM
 		[ZONE_HIGHMEM] = max_pfn - max_low_pfn,
 #endif
 	};
 	free_area_init_node(0, zones_size, ARCH_PFN_OFFSET, NULL);
 }

 /*
  * Initialize memory pages.
  */

 void __init mem_init(void)
 {
 #ifdef CONFIG_HIGHMEM
 	unsigned long tmp;

 	reset_all_zones_managed_pages();
 	for (tmp = max_low_pfn; tmp < max_pfn; tmp++)
 		free_highmem_page(pfn_to_page(tmp));
 #endif

 	max_mapnr = max_pfn - ARCH_PFN_OFFSET;
 	high_memory = (void *)__va(max_low_pfn << PAGE_SHIFT);

 	free_all_bootmem();

 	mem_init_print_info(NULL);
 	pr_info("virtual kernel memory layout:\n"
 #ifdef CONFIG_HIGHMEM
 		"    pkmap   : 0x%08lx - 0x%08lx  (%5lu kB)\n"
 		"    fixmap  : 0x%08lx - 0x%08lx  (%5lu kB)\n"
 #endif
 #ifdef CONFIG_MMU
 		"    vmalloc : 0x%08x - 0x%08x  (%5u MB)\n"
 #endif
 		"    lowmem  : 0x%08lx - 0x%08lx  (%5lu MB)\n",
 #ifdef CONFIG_HIGHMEM
 		PKMAP_BASE, PKMAP_BASE + LAST_PKMAP * PAGE_SIZE,
 		(LAST_PKMAP*PAGE_SIZE) >> 10,
 		FIXADDR_START, FIXADDR_TOP,
 		(FIXADDR_TOP - FIXADDR_START) >> 10,
 #endif
 #ifdef CONFIG_MMU
 		VMALLOC_START, VMALLOC_END,
 		(VMALLOC_END - VMALLOC_START) >> 20,
 		PAGE_OFFSET, PAGE_OFFSET +
 		(max_low_pfn - min_low_pfn) * PAGE_SIZE,
 #else
 		min_low_pfn * PAGE_SIZE, max_low_pfn * PAGE_SIZE,
 #endif
 		((max_low_pfn - min_low_pfn) * PAGE_SIZE) >> 20);
 }

 #ifdef CONFIG_BLK_DEV_INITRD
 extern int initrd_is_mapped;

 void free_initrd_mem(unsigned long start, unsigned long end)
 {
 	if (initrd_is_mapped)
 		free_reserved_area((void *)start, (void *)end, -1, "initrd");
 }
 #endif

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

 static void __init parse_memmap_one(char *p)
 {
 	char *oldp;
 	unsigned long start_at, mem_size;

 	if (!p)
 		return;

 	oldp = p;
 	mem_size = memparse(p, &p);
 	if (p == oldp)
 		return;

 	switch (*p) {
 	case '@':
 		start_at = memparse(p + 1, &p);
 		add_sysmem_bank(start_at, start_at + mem_size);
 		break;

 	case '$':
 		start_at = memparse(p + 1, &p);
 		mem_reserve(start_at, start_at + mem_size, 0);
 		break;

 	case 0:
 		mem_reserve(mem_size, 0, 0);
 		break;

 	default:
 		pr_warn("Unrecognized memmap syntax: %s\n", p);
 		break;
 	}
 }

 static int __init parse_memmap_opt(char *str)
 {
 	while (str) {
 		char *k = strchr(str, ',');

 		if (k)
 			*k++ = 0;

 		parse_memmap_one(str);
 		str = k;
 	}

 	return 0;
 }
 early_param("memmap", parse_memmap_opt);
	/*
	* arch/xtensa/mm/init.c
	*
	* Derived from MIPS, PPC.
	*
	* This file is subject to the terms and conditions of the GNU General Public
	* License. See the file "COPYING" in the main directory of this archive
	* for more details.
	*
	* Copyright (C) 2001 - 2005 Tensilica Inc.
	* Copyright (C) 2014 Cadence Design Systems Inc.
	*
	* Chris Zankel <chris@zankel.net>
	* Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
	* Marc Gauthier
	* Kevin Chea
	*/

	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/bootmem.h>
	#include <linux/gfp.h>
	#include <linux/highmem.h>
	#include <linux/swap.h>
	#include <linux/mman.h>
	#include <linux/nodemask.h>
	#include <linux/mm.h>

	#include <asm/bootparam.h>
	#include <asm/page.h>
	#include <asm/sections.h>
	#include <asm/sysmem.h>

	struct sysmem_info sysmem __initdata;

	static void __init sysmem_dump(void)
	{
	unsigned i;

	pr_debug("Sysmem:\n");
	for (i = 0; i < sysmem.nr_banks; ++i)
	pr_debug(" 0x%08lx - 0x%08lx (%ldK)\n",
	sysmem.bank[i].start, sysmem.bank[i].end,
	(sysmem.bank[i].end - sysmem.bank[i].start) >> 10);
	}

	/*
	* Find bank with maximal .start such that bank.start <= start
	*/
	static inline struct meminfo * __init find_bank(unsigned long start)
	{
	unsigned i;
	struct meminfo *it = NULL;

	for (i = 0; i < sysmem.nr_banks; ++i)
	if (sysmem.bank[i].start <= start)
	it = sysmem.bank + i;
	else
	break;
	return it;
	}

	/*
	* Move all memory banks starting at 'from' to a new place at 'to',
	* adjust nr_banks accordingly.
	* Both 'from' and 'to' must be inside the sysmem.bank.
	*
	* Returns: 0 (success), -ENOMEM (not enough space in the sysmem.bank).
	*/
	static int __init move_banks(struct meminfo to, struct meminfo from)
	{
	unsigned n = sysmem.nr_banks - (from - sysmem.bank);

	if (to > from && to - from + sysmem.nr_banks > SYSMEM_BANKS_MAX)
	return -ENOMEM;
	if (to != from)
	memmove(to, from, n * sizeof(struct meminfo));
	sysmem.nr_banks += to - from;
	return 0;
	}

	/*
	* Add new bank to sysmem. Resulting sysmem is the union of bytes of the
	* original sysmem and the new bank.
	*
	* Returns: 0 (success), < 0 (error)
	*/
	int __init add_sysmem_bank(unsigned long start, unsigned long end)
	{
	unsigned i;
	struct meminfo *it = NULL;
	unsigned long sz;
	unsigned long bank_sz = 0;

	if (start == end \|\|
	(start < end) != (PAGE_ALIGN(start) < (end & PAGE_MASK))) {
	pr_warn("Ignoring small memory bank 0x%08lx size: %ld bytes\n",
	start, end - start);
	return -EINVAL;
	}

	start = PAGE_ALIGN(start);
	end &= PAGE_MASK;
	sz = end - start;

	it = find_bank(start);

	if (it)
	bank_sz = it->end - it->start;

	if (it && bank_sz >= start - it->start) {
	if (end - it->start > bank_sz)
	it->end = end;
	else
	return 0;
	} else {
	if (!it)
	it = sysmem.bank;
	else
	++it;

	if (it - sysmem.bank < sysmem.nr_banks &&
	it->start - start <= sz) {
	it->start = start;
	if (it->end - it->start < sz)
	it->end = end;
	else
	return 0;
	} else {
	if (move_banks(it + 1, it) < 0) {
	pr_warn("Ignoring memory bank 0x%08lx size %ld bytes\n",
	start, end - start);
	return -EINVAL;
	}
	it->start = start;
	it->end = end;
	return 0;
	}
	}
	sz = it->end - it->start;
	for (i = it + 1 - sysmem.bank; i < sysmem.nr_banks; ++i)
	if (sysmem.bank[i].start - it->start <= sz) {
	if (sz < sysmem.bank[i].end - it->start)
	it->end = sysmem.bank[i].end;
	} else {
	break;
	}

	move_banks(it + 1, sysmem.bank + i);
	return 0;
	}

	/*
	* mem_reserve(start, end, must_exist)
	*
	* Reserve some memory from the memory pool.
	* If must_exist is set and a part of the region being reserved does not exist
	* memory map is not altered.
	*
	* Parameters:
	* start Start of region,
	* end End of region,
	* must_exist Must exist in memory pool.
	*
	* Returns:
	* 0 (success)
	* < 0 (error)
	*/

	int __init mem_reserve(unsigned long start, unsigned long end, int must_exist)
	{
	struct meminfo *it;
	struct meminfo *rm = NULL;
	unsigned long sz;
	unsigned long bank_sz = 0;

	start = start & PAGE_MASK;
	end = PAGE_ALIGN(end);
	sz = end - start;
	if (!sz)
	return -EINVAL;

	it = find_bank(start);

	if (it)
	bank_sz = it->end - it->start;

	if ((!it \|\| end - it->start > bank_sz) && must_exist) {
	pr_warn("mem_reserve: [0x%0lx, 0x%0lx) not in any region!\n",
	start, end);
	return -EINVAL;
	}

	if (it && start - it->start <= bank_sz) {
	if (start == it->start) {
	if (end - it->start < bank_sz) {
	it->start = end;
	return 0;
	} else {
	rm = it;
	}
	} else {
	it->end = start;
	if (end - it->start < bank_sz)
	return add_sysmem_bank(end,
	it->start + bank_sz);
	++it;
	}
	}

	if (!it)
	it = sysmem.bank;

	for (; it < sysmem.bank + sysmem.nr_banks; ++it) {
	if (it->end - start <= sz) {
	if (!rm)
	rm = it;
	} else {
	if (it->start - start < sz)
	it->start = end;
	break;
	}
	}

	if (rm)
	move_banks(rm, it);

	return 0;
	}


	/*
	* Initialize the bootmem system and give it all low memory we have available.
	*/

	void __init bootmem_init(void)
	{
	unsigned long pfn;
	unsigned long bootmap_start, bootmap_size;
	int i;

	/* Reserve all memory below PLATFORM_DEFAULT_MEM_START, as memory
	* accounting doesn't work for pages below that address.
	*
	* If PLATFORM_DEFAULT_MEM_START is zero reserve page at address 0:
	* successfull allocations should never return NULL.
	*/
	if (PLATFORM_DEFAULT_MEM_START)
	mem_reserve(0, PLATFORM_DEFAULT_MEM_START, 0);
	else
	mem_reserve(0, 1, 0);

	sysmem_dump();
	max_low_pfn = max_pfn = 0;
	min_low_pfn = ~0;

	for (i=0; i < sysmem.nr_banks; i++) {
	pfn = PAGE_ALIGN(sysmem.bank[i].start) >> PAGE_SHIFT;
	if (pfn < min_low_pfn)
	min_low_pfn = pfn;
	pfn = PAGE_ALIGN(sysmem.bank[i].end - 1) >> PAGE_SHIFT;
	if (pfn > max_pfn)
	max_pfn = pfn;
	}

	if (min_low_pfn > max_pfn)
	panic("No memory found!\n");

	max_low_pfn = max_pfn < MAX_MEM_PFN >> PAGE_SHIFT ?
	max_pfn : MAX_MEM_PFN >> PAGE_SHIFT;

	/* Find an area to use for the bootmem bitmap. */

	bootmap_size = bootmem_bootmap_pages(max_low_pfn - min_low_pfn);
	bootmap_size <<= PAGE_SHIFT;
	bootmap_start = ~0;

	for (i=0; i<sysmem.nr_banks; i++)
	if (sysmem.bank[i].end - sysmem.bank[i].start >= bootmap_size) {
	bootmap_start = sysmem.bank[i].start;
	break;
	}

	if (bootmap_start == ~0UL)
	panic("Cannot find %ld bytes for bootmap\n", bootmap_size);

	/* Reserve the bootmem bitmap area */

	mem_reserve(bootmap_start, bootmap_start + bootmap_size, 1);
	bootmap_size = init_bootmem_node(NODE_DATA(0),
	bootmap_start >> PAGE_SHIFT,
	min_low_pfn,
	max_low_pfn);

	/* Add all remaining memory pieces into the bootmem map */

	for (i = 0; i < sysmem.nr_banks; i++) {
	if (sysmem.bank[i].start >> PAGE_SHIFT < max_low_pfn) {
	unsigned long end = min(max_low_pfn << PAGE_SHIFT,
	sysmem.bank[i].end);
	free_bootmem(sysmem.bank[i].start,
	end - sysmem.bank[i].start);
	}
	}

	}


	void __init zones_init(void)
	{
	/* All pages are DMA-able, so we put them all in the DMA zone. */
	unsigned long zones_size[MAX_NR_ZONES] = {
	[ZONE_DMA] = max_low_pfn - ARCH_PFN_OFFSET,
	#ifdef CONFIG_HIGHMEM
	[ZONE_HIGHMEM] = max_pfn - max_low_pfn,
	#endif
	};
	free_area_init_node(0, zones_size, ARCH_PFN_OFFSET, NULL);
	}

	/*
	* Initialize memory pages.
	*/

	void __init mem_init(void)
	{
	#ifdef CONFIG_HIGHMEM
	unsigned long tmp;

	reset_all_zones_managed_pages();
	for (tmp = max_low_pfn; tmp < max_pfn; tmp++)
	free_highmem_page(pfn_to_page(tmp));
	#endif

	max_mapnr = max_pfn - ARCH_PFN_OFFSET;
	high_memory = (void *)__va(max_low_pfn << PAGE_SHIFT);

	free_all_bootmem();

	mem_init_print_info(NULL);
	pr_info("virtual kernel memory layout:\n"
	#ifdef CONFIG_HIGHMEM
	" pkmap : 0x%08lx - 0x%08lx (%5lu kB)\n"
	" fixmap : 0x%08lx - 0x%08lx (%5lu kB)\n"
	#endif
	#ifdef CONFIG_MMU
	" vmalloc : 0x%08x - 0x%08x (%5u MB)\n"
	#endif
	" lowmem : 0x%08lx - 0x%08lx (%5lu MB)\n",
	#ifdef CONFIG_HIGHMEM
	PKMAP_BASE, PKMAP_BASE + LAST_PKMAP * PAGE_SIZE,
	(LAST_PKMAP*PAGE_SIZE) >> 10,
	FIXADDR_START, FIXADDR_TOP,
	(FIXADDR_TOP - FIXADDR_START) >> 10,
	#endif
	#ifdef CONFIG_MMU
	VMALLOC_START, VMALLOC_END,
	(VMALLOC_END - VMALLOC_START) >> 20,
	PAGE_OFFSET, PAGE_OFFSET +
	(max_low_pfn - min_low_pfn) * PAGE_SIZE,
	#else
	min_low_pfn * PAGE_SIZE, max_low_pfn * PAGE_SIZE,
	#endif
	((max_low_pfn - min_low_pfn) * PAGE_SIZE) >> 20);
	}

	#ifdef CONFIG_BLK_DEV_INITRD
	extern int initrd_is_mapped;

	void free_initrd_mem(unsigned long start, unsigned long end)
	{
	if (initrd_is_mapped)
	free_reserved_area((void )start, (void )end, -1, "initrd");
	}
	#endif

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

	static void __init parse_memmap_one(char *p)
	{
	char *oldp;
	unsigned long start_at, mem_size;

	if (!p)
	return;

	oldp = p;
	mem_size = memparse(p, &p);
	if (p == oldp)
	return;

	switch (*p) {
	case '@':
	start_at = memparse(p + 1, &p);
	add_sysmem_bank(start_at, start_at + mem_size);
	break;

	case '$':
	start_at = memparse(p + 1, &p);
	mem_reserve(start_at, start_at + mem_size, 0);
	break;

	case 0:
	mem_reserve(mem_size, 0, 0);
	break;

	default:
	pr_warn("Unrecognized memmap syntax: %s\n", p);
	break;
	}
	}

	static int __init parse_memmap_opt(char *str)
	{
	while (str) {
	char *k = strchr(str, ',');

	if (k)
	*k++ = 0;

	parse_memmap_one(str);
	str = k;
	}

	return 0;
	}
	early_param("memmap", parse_memmap_opt);