Linux 4.6-rc6

[linux/fpc-iii.git] / arch / ia64 / mm / discontig.c

/*
 * Copyright (c) 2000, 2003 Silicon Graphics, Inc.  All rights reserved.
 * Copyright (c) 2001 Intel Corp.
 * Copyright (c) 2001 Tony Luck <tony.luck@intel.com>
 * Copyright (c) 2002 NEC Corp.
 * Copyright (c) 2002 Kimio Suganuma <k-suganuma@da.jp.nec.com>
 * Copyright (c) 2004 Silicon Graphics, Inc
 *      Russ Anderson <rja@sgi.com>
 *      Jesse Barnes <jbarnes@sgi.com>
 *      Jack Steiner <steiner@sgi.com>
 */

/*
 * Platform initialization for Discontig Memory
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/nmi.h>
#include <linux/swap.h>
#include <linux/bootmem.h>
#include <linux/acpi.h>
#include <linux/efi.h>
#include <linux/nodemask.h>
#include <linux/slab.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/meminit.h>
#include <asm/numa.h>
#include <asm/sections.h>

/*
 * Track per-node information needed to setup the boot memory allocator, the
 * per-node areas, and the real VM.
 */
struct early_node_data {
        struct ia64_node_data *node_data;
        unsigned long pernode_addr;
        unsigned long pernode_size;
#ifdef CONFIG_ZONE_DMA
        unsigned long num_dma_physpages;
#endif
        unsigned long min_pfn;
        unsigned long max_pfn;
};

static struct early_node_data mem_data[MAX_NUMNODES] __initdata;
static nodemask_t memory_less_mask __initdata;

pg_data_t *pgdat_list[MAX_NUMNODES];

/*
 * To prevent cache aliasing effects, align per-node structures so that they
 * start at addresses that are strided by node number.
 */
#define MAX_NODE_ALIGN_OFFSET   (32 * 1024 * 1024)
#define NODEDATA_ALIGN(addr, node)                                              \
        ((((addr) + 1024*1024-1) & ~(1024*1024-1)) +                            \
             (((node)*PERCPU_PAGE_SIZE) & (MAX_NODE_ALIGN_OFFSET - 1)))

/**
 * build_node_maps - callback to setup bootmem structs for each node
 * @start: physical start of range
 * @len: length of range
 * @node: node where this range resides
 *
 * We allocate a struct bootmem_data for each piece of memory that we wish to
 * treat as a virtually contiguous block (i.e. each node). Each such block
 * must start on an %IA64_GRANULE_SIZE boundary, so we round the address down
 * if necessary.  Any non-existent pages will simply be part of the virtual
 * memmap.  We also update min_low_pfn and max_low_pfn here as we receive
 * memory ranges from the caller.
 */
static int __init build_node_maps(unsigned long start, unsigned long len,
                                  int node)
{
        unsigned long spfn, epfn, end = start + len;
        struct bootmem_data *bdp = &bootmem_node_data[node];

        epfn = GRANULEROUNDUP(end) >> PAGE_SHIFT;
        spfn = GRANULEROUNDDOWN(start) >> PAGE_SHIFT;

        if (!bdp->node_low_pfn) {
                bdp->node_min_pfn = spfn;
                bdp->node_low_pfn = epfn;
        } else {
                bdp->node_min_pfn = min(spfn, bdp->node_min_pfn);
                bdp->node_low_pfn = max(epfn, bdp->node_low_pfn);
        }

        return 0;
}

/**
 * early_nr_cpus_node - return number of cpus on a given node
 * @node: node to check
 *
 * Count the number of cpus on @node.  We can't use nr_cpus_node() yet because
 * acpi_boot_init() (which builds the node_to_cpu_mask array) hasn't been
 * called yet.  Note that node 0 will also count all non-existent cpus.
 */
static int __meminit early_nr_cpus_node(int node)
{
        int cpu, n = 0;

        for_each_possible_early_cpu(cpu)
                if (node == node_cpuid[cpu].nid)
                        n++;

        return n;
}

/**
 * compute_pernodesize - compute size of pernode data
 * @node: the node id.
 */
static unsigned long __meminit compute_pernodesize(int node)
{
        unsigned long pernodesize = 0, cpus;

        cpus = early_nr_cpus_node(node);
        pernodesize += PERCPU_PAGE_SIZE * cpus;
        pernodesize += node * L1_CACHE_BYTES;
        pernodesize += L1_CACHE_ALIGN(sizeof(pg_data_t));
        pernodesize += L1_CACHE_ALIGN(sizeof(struct ia64_node_data));
        pernodesize += L1_CACHE_ALIGN(sizeof(pg_data_t));
        pernodesize = PAGE_ALIGN(pernodesize);
        return pernodesize;
}

/**
 * per_cpu_node_setup - setup per-cpu areas on each node
 * @cpu_data: per-cpu area on this node
 * @node: node to setup
 *
 * Copy the static per-cpu data into the region we just set aside and then
 * setup __per_cpu_offset for each CPU on this node.  Return a pointer to
 * the end of the area.
 */
static void *per_cpu_node_setup(void *cpu_data, int node)
{
#ifdef CONFIG_SMP
        int cpu;

        for_each_possible_early_cpu(cpu) {
                void *src = cpu == 0 ? __cpu0_per_cpu : __phys_per_cpu_start;

                if (node != node_cpuid[cpu].nid)
                        continue;

                memcpy(__va(cpu_data), src, __per_cpu_end - __per_cpu_start);
                __per_cpu_offset[cpu] = (char *)__va(cpu_data) -
                        __per_cpu_start;

                /*
                 * percpu area for cpu0 is moved from the __init area
                 * which is setup by head.S and used till this point.
                 * Update ar.k3.  This move is ensures that percpu
                 * area for cpu0 is on the correct node and its
                 * virtual address isn't insanely far from other
                 * percpu areas which is important for congruent
                 * percpu allocator.
                 */
                if (cpu == 0)
                        ia64_set_kr(IA64_KR_PER_CPU_DATA,
                                    (unsigned long)cpu_data -
                                    (unsigned long)__per_cpu_start);

                cpu_data += PERCPU_PAGE_SIZE;
        }
#endif
        return cpu_data;
}

#ifdef CONFIG_SMP
/**
 * setup_per_cpu_areas - setup percpu areas
 *
 * Arch code has already allocated and initialized percpu areas.  All
 * this function has to do is to teach the determined layout to the
 * dynamic percpu allocator, which happens to be more complex than
 * creating whole new ones using helpers.
 */
void __init setup_per_cpu_areas(void)
{
        struct pcpu_alloc_info *ai;
        struct pcpu_group_info *uninitialized_var(gi);
        unsigned int *cpu_map;
        void *base;
        unsigned long base_offset;
        unsigned int cpu;
        ssize_t static_size, reserved_size, dyn_size;
        int node, prev_node, unit, nr_units, rc;

        ai = pcpu_alloc_alloc_info(MAX_NUMNODES, nr_cpu_ids);
        if (!ai)
                panic("failed to allocate pcpu_alloc_info");
        cpu_map = ai->groups[0].cpu_map;

        /* determine base */
        base = (void *)ULONG_MAX;
        for_each_possible_cpu(cpu)
                base = min(base,
                           (void *)(__per_cpu_offset[cpu] + __per_cpu_start));
        base_offset = (void *)__per_cpu_start - base;

        /* build cpu_map, units are grouped by node */
        unit = 0;
        for_each_node(node)
                for_each_possible_cpu(cpu)
                        if (node == node_cpuid[cpu].nid)
                                cpu_map[unit++] = cpu;
        nr_units = unit;

        /* set basic parameters */
        static_size = __per_cpu_end - __per_cpu_start;
        reserved_size = PERCPU_MODULE_RESERVE;
        dyn_size = PERCPU_PAGE_SIZE - static_size - reserved_size;
        if (dyn_size < 0)
                panic("percpu area overflow static=%zd reserved=%zd\n",
                      static_size, reserved_size);

        ai->static_size         = static_size;
        ai->reserved_size       = reserved_size;
        ai->dyn_size            = dyn_size;
        ai->unit_size           = PERCPU_PAGE_SIZE;
        ai->atom_size           = PAGE_SIZE;
        ai->alloc_size          = PERCPU_PAGE_SIZE;

        /*
         * CPUs are put into groups according to node.  Walk cpu_map
         * and create new groups at node boundaries.
         */
        prev_node = -1;
        ai->nr_groups = 0;
        for (unit = 0; unit < nr_units; unit++) {
                cpu = cpu_map[unit];
                node = node_cpuid[cpu].nid;

                if (node == prev_node) {
                        gi->nr_units++;
                        continue;
                }
                prev_node = node;

                gi = &ai->groups[ai->nr_groups++];
                gi->nr_units            = 1;
                gi->base_offset         = __per_cpu_offset[cpu] + base_offset;
                gi->cpu_map             = &cpu_map[unit];
        }

        rc = pcpu_setup_first_chunk(ai, base);
        if (rc)
                panic("failed to setup percpu area (err=%d)", rc);

        pcpu_free_alloc_info(ai);
}
#endif

/**
 * fill_pernode - initialize pernode data.
 * @node: the node id.
 * @pernode: physical address of pernode data
 * @pernodesize: size of the pernode data
 */
static void __init fill_pernode(int node, unsigned long pernode,
        unsigned long pernodesize)
{
        void *cpu_data;
        int cpus = early_nr_cpus_node(node);
        struct bootmem_data *bdp = &bootmem_node_data[node];

        mem_data[node].pernode_addr = pernode;
        mem_data[node].pernode_size = pernodesize;
        memset(__va(pernode), 0, pernodesize);

        cpu_data = (void *)pernode;
        pernode += PERCPU_PAGE_SIZE * cpus;
        pernode += node * L1_CACHE_BYTES;

        pgdat_list[node] = __va(pernode);
        pernode += L1_CACHE_ALIGN(sizeof(pg_data_t));

        mem_data[node].node_data = __va(pernode);
        pernode += L1_CACHE_ALIGN(sizeof(struct ia64_node_data));

        pgdat_list[node]->bdata = bdp;
        pernode += L1_CACHE_ALIGN(sizeof(pg_data_t));

        cpu_data = per_cpu_node_setup(cpu_data, node);

        return;
}

/**
 * find_pernode_space - allocate memory for memory map and per-node structures
 * @start: physical start of range
 * @len: length of range
 * @node: node where this range resides
 *
 * This routine reserves space for the per-cpu data struct, the list of
 * pg_data_ts and the per-node data struct.  Each node will have something like
 * the following in the first chunk of addr. space large enough to hold it.
 *
 *    ________________________
 *   |                        |
 *   |~~~~~~~~~~~~~~~~~~~~~~~~| <-- NODEDATA_ALIGN(start, node) for the first
 *   |    PERCPU_PAGE_SIZE *  |     start and length big enough
 *   |    cpus_on_this_node   | Node 0 will also have entries for all non-existent cpus.
 *   |------------------------|
 *   |   local pg_data_t *    |
 *   |------------------------|
 *   |  local ia64_node_data  |
 *   |------------------------|
 *   |          ???           |
 *   |________________________|
 *
 * Once this space has been set aside, the bootmem maps are initialized.  We
 * could probably move the allocation of the per-cpu and ia64_node_data space
 * outside of this function and use alloc_bootmem_node(), but doing it here
 * is straightforward and we get the alignments we want so...
 */
static int __init find_pernode_space(unsigned long start, unsigned long len,
                                     int node)
{
        unsigned long spfn, epfn;
        unsigned long pernodesize = 0, pernode, pages, mapsize;
        struct bootmem_data *bdp = &bootmem_node_data[node];

        spfn = start >> PAGE_SHIFT;
        epfn = (start + len) >> PAGE_SHIFT;

        pages = bdp->node_low_pfn - bdp->node_min_pfn;
        mapsize = bootmem_bootmap_pages(pages) << PAGE_SHIFT;

        /*
         * Make sure this memory falls within this node's usable memory
         * since we may have thrown some away in build_maps().
         */
        if (spfn < bdp->node_min_pfn || epfn > bdp->node_low_pfn)
                return 0;

        /* Don't setup this node's local space twice... */
        if (mem_data[node].pernode_addr)
                return 0;

        /*
         * Calculate total size needed, incl. what's necessary
         * for good alignment and alias prevention.
         */
        pernodesize = compute_pernodesize(node);
        pernode = NODEDATA_ALIGN(start, node);

        /* Is this range big enough for what we want to store here? */
        if (start + len > (pernode + pernodesize + mapsize))
                fill_pernode(node, pernode, pernodesize);

        return 0;
}

/**
 * free_node_bootmem - free bootmem allocator memory for use
 * @start: physical start of range
 * @len: length of range
 * @node: node where this range resides
 *
 * Simply calls the bootmem allocator to free the specified ranged from
 * the given pg_data_t's bdata struct.  After this function has been called
 * for all the entries in the EFI memory map, the bootmem allocator will
 * be ready to service allocation requests.
 */
static int __init free_node_bootmem(unsigned long start, unsigned long len,
                                    int node)
{
        free_bootmem_node(pgdat_list[node], start, len);

        return 0;
}

/**
 * reserve_pernode_space - reserve memory for per-node space
 *
 * Reserve the space used by the bootmem maps & per-node space in the boot
 * allocator so that when we actually create the real mem maps we don't
 * use their memory.
 */
static void __init reserve_pernode_space(void)
{
        unsigned long base, size, pages;
        struct bootmem_data *bdp;
        int node;

        for_each_online_node(node) {
                pg_data_t *pdp = pgdat_list[node];

                if (node_isset(node, memory_less_mask))
                        continue;

                bdp = pdp->bdata;

                /* First the bootmem_map itself */
                pages = bdp->node_low_pfn - bdp->node_min_pfn;
                size = bootmem_bootmap_pages(pages) << PAGE_SHIFT;
                base = __pa(bdp->node_bootmem_map);
                reserve_bootmem_node(pdp, base, size, BOOTMEM_DEFAULT);

                /* Now the per-node space */
                size = mem_data[node].pernode_size;
                base = __pa(mem_data[node].pernode_addr);
                reserve_bootmem_node(pdp, base, size, BOOTMEM_DEFAULT);
        }
}

static void __meminit scatter_node_data(void)
{
        pg_data_t **dst;
        int node;

        /*
         * for_each_online_node() can't be used at here.
         * node_online_map is not set for hot-added nodes at this time,
         * because we are halfway through initialization of the new node's
         * structures.  If for_each_online_node() is used, a new node's
         * pg_data_ptrs will be not initialized. Instead of using it,
         * pgdat_list[] is checked.
         */
        for_each_node(node) {
                if (pgdat_list[node]) {
                        dst = LOCAL_DATA_ADDR(pgdat_list[node])->pg_data_ptrs;
                        memcpy(dst, pgdat_list, sizeof(pgdat_list));
                }
        }
}

/**
 * initialize_pernode_data - fixup per-cpu & per-node pointers
 *
 * Each node's per-node area has a copy of the global pg_data_t list, so
 * we copy that to each node here, as well as setting the per-cpu pointer
 * to the local node data structure.  The active_cpus field of the per-node
 * structure gets setup by the platform_cpu_init() function later.
 */
static void __init initialize_pernode_data(void)
{
        int cpu, node;

        scatter_node_data();

#ifdef CONFIG_SMP
        /* Set the node_data pointer for each per-cpu struct */
        for_each_possible_early_cpu(cpu) {
                node = node_cpuid[cpu].nid;
                per_cpu(ia64_cpu_info, cpu).node_data =
                        mem_data[node].node_data;
        }
#else
        {
                struct cpuinfo_ia64 *cpu0_cpu_info;
                cpu = 0;
                node = node_cpuid[cpu].nid;
                cpu0_cpu_info = (struct cpuinfo_ia64 *)(__phys_per_cpu_start +
                        ((char *)&ia64_cpu_info - __per_cpu_start));
                cpu0_cpu_info->node_data = mem_data[node].node_data;
        }
#endif /* CONFIG_SMP */
}

/**
 * memory_less_node_alloc - * attempt to allocate memory on the best NUMA slit
 *      node but fall back to any other node when __alloc_bootmem_node fails
 *      for best.
 * @nid: node id
 * @pernodesize: size of this node's pernode data
 */
static void __init *memory_less_node_alloc(int nid, unsigned long pernodesize)
{
        void *ptr = NULL;
        u8 best = 0xff;
        int bestnode = -1, node, anynode = 0;

        for_each_online_node(node) {
                if (node_isset(node, memory_less_mask))
                        continue;
                else if (node_distance(nid, node) < best) {
                        best = node_distance(nid, node);
                        bestnode = node;
                }
                anynode = node;
        }

        if (bestnode == -1)
                bestnode = anynode;

        ptr = __alloc_bootmem_node(pgdat_list[bestnode], pernodesize,
                PERCPU_PAGE_SIZE, __pa(MAX_DMA_ADDRESS));

        return ptr;
}

/**
 * memory_less_nodes - allocate and initialize CPU only nodes pernode
 *      information.
 */
static void __init memory_less_nodes(void)
{
        unsigned long pernodesize;
        void *pernode;
        int node;

        for_each_node_mask(node, memory_less_mask) {
                pernodesize = compute_pernodesize(node);
                pernode = memory_less_node_alloc(node, pernodesize);
                fill_pernode(node, __pa(pernode), pernodesize);
        }

        return;
}

/**
 * find_memory - walk the EFI memory map and setup the bootmem allocator
 *
 * Called early in boot to setup the bootmem allocator, and to
 * allocate the per-cpu and per-node structures.
 */
void __init find_memory(void)
{
        int node;

        reserve_memory();

        if (num_online_nodes() == 0) {
                printk(KERN_ERR "node info missing!\n");
                node_set_online(0);
        }

        nodes_or(memory_less_mask, memory_less_mask, node_online_map);
        min_low_pfn = -1;
        max_low_pfn = 0;

        /* These actually end up getting called by call_pernode_memory() */
        efi_memmap_walk(filter_rsvd_memory, build_node_maps);
        efi_memmap_walk(filter_rsvd_memory, find_pernode_space);
        efi_memmap_walk(find_max_min_low_pfn, NULL);

        for_each_online_node(node)
                if (bootmem_node_data[node].node_low_pfn) {
                        node_clear(node, memory_less_mask);
                        mem_data[node].min_pfn = ~0UL;
                }

        efi_memmap_walk(filter_memory, register_active_ranges);

        /*
         * Initialize the boot memory maps in reverse order since that's
         * what the bootmem allocator expects
         */
        for (node = MAX_NUMNODES - 1; node >= 0; node--) {
                unsigned long pernode, pernodesize, map;
                struct bootmem_data *bdp;

                if (!node_online(node))
                        continue;
                else if (node_isset(node, memory_less_mask))
                        continue;

                bdp = &bootmem_node_data[node];
                pernode = mem_data[node].pernode_addr;
                pernodesize = mem_data[node].pernode_size;
                map = pernode + pernodesize;

                init_bootmem_node(pgdat_list[node],
                                  map>>PAGE_SHIFT,
                                  bdp->node_min_pfn,
                                  bdp->node_low_pfn);
        }

        efi_memmap_walk(filter_rsvd_memory, free_node_bootmem);

        reserve_pernode_space();
        memory_less_nodes();
        initialize_pernode_data();

        max_pfn = max_low_pfn;

        find_initrd();
}

#ifdef CONFIG_SMP
/**
 * per_cpu_init - setup per-cpu variables
 *
 * find_pernode_space() does most of this already, we just need to set
 * local_per_cpu_offset
 */
void *per_cpu_init(void)
{
        int cpu;
        static int first_time = 1;

        if (first_time) {
                first_time = 0;
                for_each_possible_early_cpu(cpu)
                        per_cpu(local_per_cpu_offset, cpu) = __per_cpu_offset[cpu];
        }

        return __per_cpu_start + __per_cpu_offset[smp_processor_id()];
}
#endif /* CONFIG_SMP */

/**
 * call_pernode_memory - use SRAT to call callback functions with node info
 * @start: physical start of range
 * @len: length of range
 * @arg: function to call for each range
 *
 * efi_memmap_walk() knows nothing about layout of memory across nodes. Find
 * out to which node a block of memory belongs.  Ignore memory that we cannot
 * identify, and split blocks that run across multiple nodes.
 *
 * Take this opportunity to round the start address up and the end address
 * down to page boundaries.
 */
void call_pernode_memory(unsigned long start, unsigned long len, void *arg)
{
        unsigned long rs, re, end = start + len;
        void (*func)(unsigned long, unsigned long, int);
        int i;

        start = PAGE_ALIGN(start);
        end &= PAGE_MASK;
        if (start >= end)
                return;

        func = arg;

        if (!num_node_memblks) {
                /* No SRAT table, so assume one node (node 0) */
                if (start < end)
                        (*func)(start, end - start, 0);
                return;
        }

        for (i = 0; i < num_node_memblks; i++) {
                rs = max(start, node_memblk[i].start_paddr);
                re = min(end, node_memblk[i].start_paddr +
                         node_memblk[i].size);

                if (rs < re)
                        (*func)(rs, re - rs, node_memblk[i].nid);

                if (re == end)
                        break;
        }
}

/**
 * count_node_pages - callback to build per-node memory info structures
 * @start: physical start of range
 * @len: length of range
 * @node: node where this range resides
 *
 * Each node has it's own number of physical pages, DMAable pages, start, and
 * end page frame number.  This routine will be called by call_pernode_memory()
 * for each piece of usable memory and will setup these values for each node.
 * Very similar to build_maps().
 */
static __init int count_node_pages(unsigned long start, unsigned long len, int node)
{
        unsigned long end = start + len;

#ifdef CONFIG_ZONE_DMA
        if (start <= __pa(MAX_DMA_ADDRESS))
                mem_data[node].num_dma_physpages +=
                        (min(end, __pa(MAX_DMA_ADDRESS)) - start) >>PAGE_SHIFT;
#endif
        start = GRANULEROUNDDOWN(start);
        end = GRANULEROUNDUP(end);
        mem_data[node].max_pfn = max(mem_data[node].max_pfn,
                                     end >> PAGE_SHIFT);
        mem_data[node].min_pfn = min(mem_data[node].min_pfn,
                                     start >> PAGE_SHIFT);

        return 0;
}

/**
 * paging_init - setup page tables
 *
 * paging_init() sets up the page tables for each node of the system and frees
 * the bootmem allocator memory for general use.
 */
void __init paging_init(void)
{
        unsigned long max_dma;
        unsigned long pfn_offset = 0;
        unsigned long max_pfn = 0;
        int node;
        unsigned long max_zone_pfns[MAX_NR_ZONES];

        max_dma = virt_to_phys((void *) MAX_DMA_ADDRESS) >> PAGE_SHIFT;

        efi_memmap_walk(filter_rsvd_memory, count_node_pages);

        sparse_memory_present_with_active_regions(MAX_NUMNODES);
        sparse_init();

#ifdef CONFIG_VIRTUAL_MEM_MAP
        VMALLOC_END -= PAGE_ALIGN(ALIGN(max_low_pfn, MAX_ORDER_NR_PAGES) *
                sizeof(struct page));
        vmem_map = (struct page *) VMALLOC_END;
        efi_memmap_walk(create_mem_map_page_table, NULL);
        printk("Virtual mem_map starts at 0x%p\n", vmem_map);
#endif

        for_each_online_node(node) {
                pfn_offset = mem_data[node].min_pfn;

#ifdef CONFIG_VIRTUAL_MEM_MAP
                NODE_DATA(node)->node_mem_map = vmem_map + pfn_offset;
#endif
                if (mem_data[node].max_pfn > max_pfn)
                        max_pfn = mem_data[node].max_pfn;
        }

        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
#ifdef CONFIG_ZONE_DMA
        max_zone_pfns[ZONE_DMA] = max_dma;
#endif
        max_zone_pfns[ZONE_NORMAL] = max_pfn;
        free_area_init_nodes(max_zone_pfns);

        zero_page_memmap_ptr = virt_to_page(ia64_imva(empty_zero_page));
}

#ifdef CONFIG_MEMORY_HOTPLUG
pg_data_t *arch_alloc_nodedata(int nid)
{
        unsigned long size = compute_pernodesize(nid);

        return kzalloc(size, GFP_KERNEL);
}

void arch_free_nodedata(pg_data_t *pgdat)
{
        kfree(pgdat);
}

void arch_refresh_nodedata(int update_node, pg_data_t *update_pgdat)
{
        pgdat_list[update_node] = update_pgdat;
        scatter_node_data();
}
#endif

#ifdef CONFIG_SPARSEMEM_VMEMMAP
int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
{
        return vmemmap_populate_basepages(start, end, node);
}

void vmemmap_free(unsigned long start, unsigned long end)
{
}
#endif