[apple/xnu.git] / osfmk / vm / vm_resident.c

/*
 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
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/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *      File:   vm/vm_page.c
 *      Author: Avadis Tevanian, Jr., Michael Wayne Young
 *
 *      Resident memory management module.
 */

#include <debug.h>
#include <libkern/OSAtomic.h>

#include <mach/clock_types.h>
#include <mach/vm_prot.h>
#include <mach/vm_statistics.h>
#include <mach/sdt.h>
#include <kern/counters.h>
#include <kern/sched_prim.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/zalloc.h>
#include <kern/xpr.h>
#include <vm/pmap.h>
#include <vm/vm_init.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_kern.h>                 /* kernel_memory_allocate() */
#include <kern/misc_protos.h>
#include <zone_debug.h>
#include <vm/cpm.h>
#include <ppc/mappings.h>               /* (BRINGUP) */
#include <pexpert/pexpert.h>    /* (BRINGUP) */

#include <vm/vm_protos.h>
#include <vm/memory_object.h>
#include <vm/vm_purgeable_internal.h>

#if CONFIG_EMBEDDED
#include <sys/kern_memorystatus.h>
#endif

int                     speculative_age_index = 0;
int                     speculative_steal_index = 0;

struct vm_speculative_age_q vm_page_queue_speculative[VM_PAGE_MAX_SPECULATIVE_AGE_Q + 1];


/*
 *      Associated with page of user-allocatable memory is a
 *      page structure.
 */

/*
 *      These variables record the values returned by vm_page_bootstrap,
 *      for debugging purposes.  The implementation of pmap_steal_memory
 *      and pmap_startup here also uses them internally.
 */

vm_offset_t virtual_space_start;
vm_offset_t virtual_space_end;
int     vm_page_pages;

/*
 *      The vm_page_lookup() routine, which provides for fast
 *      (virtual memory object, offset) to page lookup, employs
 *      the following hash table.  The vm_page_{insert,remove}
 *      routines install and remove associations in the table.
 *      [This table is often called the virtual-to-physical,
 *      or VP, table.]
 */
typedef struct {
        vm_page_t       pages;
#if     MACH_PAGE_HASH_STATS
        int             cur_count;              /* current count */
        int             hi_count;               /* high water mark */
#endif /* MACH_PAGE_HASH_STATS */
} vm_page_bucket_t;

vm_page_bucket_t *vm_page_buckets;              /* Array of buckets */
unsigned int    vm_page_bucket_count = 0;       /* How big is array? */
unsigned int    vm_page_hash_mask;              /* Mask for hash function */
unsigned int    vm_page_hash_shift;             /* Shift for hash function */
uint32_t        vm_page_bucket_hash;            /* Basic bucket hash */
decl_simple_lock_data(,vm_page_bucket_lock)


#if     MACH_PAGE_HASH_STATS
/* This routine is only for debug.  It is intended to be called by
 * hand by a developer using a kernel debugger.  This routine prints
 * out vm_page_hash table statistics to the kernel debug console.
 */
void
hash_debug(void)
{
        int     i;
        int     numbuckets = 0;
        int     highsum = 0;
        int     maxdepth = 0;

        for (i = 0; i < vm_page_bucket_count; i++) {
                if (vm_page_buckets[i].hi_count) {
                        numbuckets++;
                        highsum += vm_page_buckets[i].hi_count;
                        if (vm_page_buckets[i].hi_count > maxdepth)
                                maxdepth = vm_page_buckets[i].hi_count;
                }
        }
        printf("Total number of buckets: %d\n", vm_page_bucket_count);
        printf("Number used buckets:     %d = %d%%\n",
                numbuckets, 100*numbuckets/vm_page_bucket_count);
        printf("Number unused buckets:   %d = %d%%\n",
                vm_page_bucket_count - numbuckets,
                100*(vm_page_bucket_count-numbuckets)/vm_page_bucket_count);
        printf("Sum of bucket max depth: %d\n", highsum);
        printf("Average bucket depth:    %d.%2d\n",
                highsum/vm_page_bucket_count,
                highsum%vm_page_bucket_count);
        printf("Maximum bucket depth:    %d\n", maxdepth);
}
#endif /* MACH_PAGE_HASH_STATS */

/*
 *      The virtual page size is currently implemented as a runtime
 *      variable, but is constant once initialized using vm_set_page_size.
 *      This initialization must be done in the machine-dependent
 *      bootstrap sequence, before calling other machine-independent
 *      initializations.
 *
 *      All references to the virtual page size outside this
 *      module must use the PAGE_SIZE, PAGE_MASK and PAGE_SHIFT
 *      constants.
 */
vm_size_t       page_size  = PAGE_SIZE;
vm_size_t       page_mask  = PAGE_MASK;
int             page_shift = PAGE_SHIFT;

/*
 *      Resident page structures are initialized from
 *      a template (see vm_page_alloc).
 *
 *      When adding a new field to the virtual memory
 *      object structure, be sure to add initialization
 *      (see vm_page_bootstrap).
 */
struct vm_page  vm_page_template;

vm_page_t       vm_pages = VM_PAGE_NULL;
unsigned int    vm_pages_count = 0;

/*
 *      Resident pages that represent real memory
 *      are allocated from a set of free lists,
 *      one per color.
 */
unsigned int    vm_colors;
unsigned int    vm_color_mask;                  /* mask is == (vm_colors-1) */
unsigned int    vm_cache_geometry_colors = 0;   /* set by hw dependent code during startup */
queue_head_t    vm_page_queue_free[MAX_COLORS];
vm_page_t       vm_page_queue_fictitious;
unsigned int    vm_page_free_wanted;
unsigned int    vm_page_free_wanted_privileged;
unsigned int    vm_page_free_count;
unsigned int    vm_page_fictitious_count;

unsigned int    vm_page_free_count_minimum;     /* debugging */

/*
 *      Occasionally, the virtual memory system uses
 *      resident page structures that do not refer to
 *      real pages, for example to leave a page with
 *      important state information in the VP table.
 *
 *      These page structures are allocated the way
 *      most other kernel structures are.
 */
zone_t  vm_page_zone;
decl_mutex_data(,vm_page_alloc_lock)
unsigned int io_throttle_zero_fill;

/*
 *      Fictitious pages don't have a physical address,
 *      but we must initialize phys_page to something.
 *      For debugging, this should be a strange value
 *      that the pmap module can recognize in assertions.
 */
vm_offset_t vm_page_fictitious_addr = (vm_offset_t) -1;

/*
 *      Guard pages are not accessible so they don't
 *      need a physical address, but we need to enter
 *      one in the pmap.
 *      Let's make it recognizable and make sure that
 *      we don't use a real physical page with that
 *      physical address.
 */
vm_offset_t vm_page_guard_addr = (vm_offset_t) -2;

/*
 *      Resident page structures are also chained on
 *      queues that are used by the page replacement
 *      system (pageout daemon).  These queues are
 *      defined here, but are shared by the pageout
 *      module.  The inactive queue is broken into 
 *      inactive and zf for convenience as the 
 *      pageout daemon often assignes a higher 
 *      affinity to zf pages
 */
queue_head_t    vm_page_queue_active;
queue_head_t    vm_page_queue_inactive;
queue_head_t    vm_page_queue_zf;       /* inactive memory queue for zero fill */

unsigned int    vm_page_active_count;
unsigned int    vm_page_inactive_count;
unsigned int    vm_page_throttled_count;
unsigned int    vm_page_speculative_count;
unsigned int    vm_page_wire_count;
unsigned int    vm_page_gobble_count = 0;
unsigned int    vm_page_wire_count_warning = 0;
unsigned int    vm_page_gobble_count_warning = 0;

unsigned int    vm_page_purgeable_count = 0; /* # of pages purgeable now */
uint64_t        vm_page_purged_count = 0;    /* total count of purged pages */

unsigned int    vm_page_speculative_recreated = 0;
unsigned int    vm_page_speculative_created = 0;
unsigned int    vm_page_speculative_used = 0;

ppnum_t         vm_lopage_poolstart = 0;
ppnum_t         vm_lopage_poolend = 0;
int             vm_lopage_poolsize = 0;
uint64_t        max_valid_dma_address = 0xffffffffffffffffULL;


/*
 *      Several page replacement parameters are also
 *      shared with this module, so that page allocation
 *      (done here in vm_page_alloc) can trigger the
 *      pageout daemon.
 */
unsigned int    vm_page_free_target = 0;
unsigned int    vm_page_free_min = 0;
unsigned int    vm_page_inactive_target = 0;
unsigned int    vm_page_inactive_min = 0;
unsigned int    vm_page_free_reserved = 0;
unsigned int    vm_page_zfill_throttle_count = 0;

/*
 *      The VM system has a couple of heuristics for deciding
 *      that pages are "uninteresting" and should be placed
 *      on the inactive queue as likely candidates for replacement.
 *      These variables let the heuristics be controlled at run-time
 *      to make experimentation easier.
 */

boolean_t vm_page_deactivate_hint = TRUE;

/*
 *      vm_set_page_size:
 *
 *      Sets the page size, perhaps based upon the memory
 *      size.  Must be called before any use of page-size
 *      dependent functions.
 *
 *      Sets page_shift and page_mask from page_size.
 */
void
vm_set_page_size(void)
{
        page_mask = page_size - 1;

        if ((page_mask & page_size) != 0)
                panic("vm_set_page_size: page size not a power of two");

        for (page_shift = 0; ; page_shift++)
                if ((1U << page_shift) == page_size)
                        break;
}


/* Called once during statup, once the cache geometry is known.
 */
static void
vm_page_set_colors( void )
{
        unsigned int    n, override;
        
        if ( PE_parse_boot_arg("colors", &override) )           /* colors specified as a boot-arg? */
                n = override;   
        else if ( vm_cache_geometry_colors )                    /* do we know what the cache geometry is? */
                n = vm_cache_geometry_colors;
        else    n = DEFAULT_COLORS;                             /* use default if all else fails */

        if ( n == 0 )
                n = 1;
        if ( n > MAX_COLORS )
                n = MAX_COLORS;
                
        /* the count must be a power of 2  */
        if ( ( n & (n - 1)) !=0  )
                panic("vm_page_set_colors");
        
        vm_colors = n;
        vm_color_mask = n - 1;
}


/*
 *      vm_page_bootstrap:
 *
 *      Initializes the resident memory module.
 *
 *      Allocates memory for the page cells, and
 *      for the object/offset-to-page hash table headers.
 *      Each page cell is initialized and placed on the free list.
 *      Returns the range of available kernel virtual memory.
 */

void
vm_page_bootstrap(
        vm_offset_t             *startp,
        vm_offset_t             *endp)
{
        register vm_page_t      m;
        unsigned int            i;
        unsigned int            log1;
        unsigned int            log2;
        unsigned int            size;

        /*
         *      Initialize the vm_page template.
         */

        m = &vm_page_template;
        m->object = VM_OBJECT_NULL;             /* reset later */
        m->offset = (vm_object_offset_t) -1;    /* reset later */
        m->wire_count = 0;

        m->pageq.next = NULL;
        m->pageq.prev = NULL;
        m->listq.next = NULL;
        m->listq.prev = NULL;

        m->speculative = FALSE;
        m->throttled = FALSE;
        m->inactive = FALSE;
        m->active = FALSE;
        m->no_cache = FALSE;
        m->laundry = FALSE;
        m->free = FALSE;
        m->pmapped = FALSE;
        m->wpmapped = FALSE;
        m->reference = FALSE;
        m->pageout = FALSE;
        m->dump_cleaning = FALSE;
        m->list_req_pending = FALSE;

        m->busy = TRUE;
        m->wanted = FALSE;
        m->tabled = FALSE;
        m->fictitious = FALSE;
        m->private = FALSE;
        m->absent = FALSE;
        m->error = FALSE;
        m->dirty = FALSE;
        m->cleaning = FALSE;
        m->precious = FALSE;
        m->clustered = FALSE;
        m->unusual = FALSE;
        m->restart = FALSE;
        m->zero_fill = FALSE;
        m->encrypted = FALSE;
        m->encrypted_cleaning = FALSE;
        m->deactivated = FALSE;

        m->phys_page = 0;               /* reset later */

        /*
         *      Initialize the page queues.
         */

        mutex_init(&vm_page_queue_free_lock, 0);
        mutex_init(&vm_page_queue_lock, 0);

        mutex_init(&vm_purgeable_queue_lock, 0);
    
        for (i = 0; i < PURGEABLE_Q_TYPE_MAX; i++) {
                int group;

                purgeable_queues[i].token_q_head = 0;
                purgeable_queues[i].token_q_tail = 0;
                for (group = 0; group < NUM_VOLATILE_GROUPS; group++)
                        queue_init(&purgeable_queues[i].objq[group]);

                purgeable_queues[i].type = i;
                purgeable_queues[i].new_pages = 0;
#if MACH_ASSERT
                purgeable_queues[i].debug_count_tokens = 0;
                purgeable_queues[i].debug_count_objects = 0;
#endif
        };
    
        for (i = 0; i < MAX_COLORS; i++ )
                queue_init(&vm_page_queue_free[i]);
        queue_init(&vm_lopage_queue_free);
        vm_page_queue_fictitious = VM_PAGE_NULL;
        queue_init(&vm_page_queue_active);
        queue_init(&vm_page_queue_inactive);
        queue_init(&vm_page_queue_throttled);
        queue_init(&vm_page_queue_zf);

        for ( i = 0; i <= VM_PAGE_MAX_SPECULATIVE_AGE_Q; i++ ) {
                queue_init(&vm_page_queue_speculative[i].age_q);

                vm_page_queue_speculative[i].age_ts.tv_sec = 0;
                vm_page_queue_speculative[i].age_ts.tv_nsec = 0;
        }
        vm_page_free_wanted = 0;
        vm_page_free_wanted_privileged = 0;
        
        vm_page_set_colors();


        /*
         *      Steal memory for the map and zone subsystems.
         */

        vm_map_steal_memory();
        zone_steal_memory();

        /*
         *      Allocate (and initialize) the virtual-to-physical
         *      table hash buckets.
         *
         *      The number of buckets should be a power of two to
         *      get a good hash function.  The following computation
         *      chooses the first power of two that is greater
         *      than the number of physical pages in the system.
         */

        simple_lock_init(&vm_page_bucket_lock, 0);
        
        if (vm_page_bucket_count == 0) {
                unsigned int npages = pmap_free_pages();

                vm_page_bucket_count = 1;
                while (vm_page_bucket_count < npages)
                        vm_page_bucket_count <<= 1;
        }

        vm_page_hash_mask = vm_page_bucket_count - 1;

        /*
         *      Calculate object shift value for hashing algorithm:
         *              O = log2(sizeof(struct vm_object))
         *              B = log2(vm_page_bucket_count)
         *              hash shifts the object left by
         *              B/2 - O
         */
        size = vm_page_bucket_count;
        for (log1 = 0; size > 1; log1++) 
                size /= 2;
        size = sizeof(struct vm_object);
        for (log2 = 0; size > 1; log2++) 
                size /= 2;
        vm_page_hash_shift = log1/2 - log2 + 1;
        
        vm_page_bucket_hash = 1 << ((log1 + 1) >> 1);           /* Get (ceiling of sqrt of table size) */
        vm_page_bucket_hash |= 1 << ((log1 + 1) >> 2);          /* Get (ceiling of quadroot of table size) */
        vm_page_bucket_hash |= 1;                                                       /* Set bit and add 1 - always must be 1 to insure unique series */

        if (vm_page_hash_mask & vm_page_bucket_count)
                printf("vm_page_bootstrap: WARNING -- strange page hash\n");

        vm_page_buckets = (vm_page_bucket_t *)
                pmap_steal_memory(vm_page_bucket_count *
                                  sizeof(vm_page_bucket_t));

        for (i = 0; i < vm_page_bucket_count; i++) {
                register vm_page_bucket_t *bucket = &vm_page_buckets[i];

                bucket->pages = VM_PAGE_NULL;
#if     MACH_PAGE_HASH_STATS
                bucket->cur_count = 0;
                bucket->hi_count = 0;
#endif /* MACH_PAGE_HASH_STATS */
        }

        /*
         *      Machine-dependent code allocates the resident page table.
         *      It uses vm_page_init to initialize the page frames.
         *      The code also returns to us the virtual space available
         *      to the kernel.  We don't trust the pmap module
         *      to get the alignment right.
         */

        pmap_startup(&virtual_space_start, &virtual_space_end);
        virtual_space_start = round_page(virtual_space_start);
        virtual_space_end = trunc_page(virtual_space_end);

        *startp = virtual_space_start;
        *endp = virtual_space_end;

        /*
         *      Compute the initial "wire" count.
         *      Up until now, the pages which have been set aside are not under 
         *      the VM system's control, so although they aren't explicitly
         *      wired, they nonetheless can't be moved. At this moment,
         *      all VM managed pages are "free", courtesy of pmap_startup.
         */
        vm_page_wire_count = atop_64(max_mem) - vm_page_free_count;     /* initial value */
        vm_page_free_count_minimum = vm_page_free_count;

        printf("vm_page_bootstrap: %d free pages and %d wired pages\n",
               vm_page_free_count, vm_page_wire_count);

        simple_lock_init(&vm_paging_lock, 0);
}

#ifndef MACHINE_PAGES
/*
 *      We implement pmap_steal_memory and pmap_startup with the help
 *      of two simpler functions, pmap_virtual_space and pmap_next_page.
 */

void *
pmap_steal_memory(
        vm_size_t size)
{
        vm_offset_t addr, vaddr;
        ppnum_t phys_page;

        /*
         *      We round the size to a round multiple.
         */

        size = (size + sizeof (void *) - 1) &~ (sizeof (void *) - 1);

        /*
         *      If this is the first call to pmap_steal_memory,
         *      we have to initialize ourself.
         */

        if (virtual_space_start == virtual_space_end) {
                pmap_virtual_space(&virtual_space_start, &virtual_space_end);

                /*
                 *      The initial values must be aligned properly, and
                 *      we don't trust the pmap module to do it right.
                 */

                virtual_space_start = round_page(virtual_space_start);
                virtual_space_end = trunc_page(virtual_space_end);
        }

        /*
         *      Allocate virtual memory for this request.
         */

        addr = virtual_space_start;
        virtual_space_start += size;

        kprintf("pmap_steal_memory: %08X - %08X; size=%08X\n", addr, virtual_space_start, size);        /* (TEST/DEBUG) */

        /*
         *      Allocate and map physical pages to back new virtual pages.
         */

        for (vaddr = round_page(addr);
             vaddr < addr + size;
             vaddr += PAGE_SIZE) {
                if (!pmap_next_page(&phys_page))
                        panic("pmap_steal_memory");

                /*
                 *      XXX Logically, these mappings should be wired,
                 *      but some pmap modules barf if they are.
                 */

                pmap_enter(kernel_pmap, vaddr, phys_page,
                           VM_PROT_READ|VM_PROT_WRITE, 
                                VM_WIMG_USE_DEFAULT, FALSE);
                /*
                 * Account for newly stolen memory
                 */
                vm_page_wire_count++;

        }

        return (void *) addr;
}

void
pmap_startup(
        vm_offset_t *startp,
        vm_offset_t *endp)
{
        unsigned int i, npages, pages_initialized, fill, fillval;
        ppnum_t         phys_page;
        addr64_t        tmpaddr;
        unsigned int    num_of_lopages = 0;
        unsigned int    last_index;

        /*
         *      We calculate how many page frames we will have
         *      and then allocate the page structures in one chunk.
         */

        tmpaddr = (addr64_t)pmap_free_pages() * (addr64_t)PAGE_SIZE;    /* Get the amount of memory left */
        tmpaddr = tmpaddr + (addr64_t)(round_page_32(virtual_space_start) - virtual_space_start);       /* Account for any slop */
        npages = (unsigned int)(tmpaddr / (addr64_t)(PAGE_SIZE + sizeof(*vm_pages)));   /* Figure size of all vm_page_ts, including enough to hold the vm_page_ts */

        vm_pages = (vm_page_t) pmap_steal_memory(npages * sizeof *vm_pages);

        /*
         *      Initialize the page frames.
         */
        for (i = 0, pages_initialized = 0; i < npages; i++) {
                if (!pmap_next_page(&phys_page))
                        break;

                vm_page_init(&vm_pages[i], phys_page);
                vm_page_pages++;
                pages_initialized++;
        }
        vm_pages_count = pages_initialized;

        /*
         * Check if we want to initialize pages to a known value
         */
        fill = 0;                                                               /* Assume no fill */
        if (PE_parse_boot_arg("fill", &fillval)) fill = 1;                      /* Set fill */
        

        /*
         * if vm_lopage_poolsize is non-zero, than we need to reserve
         * a pool of pages whose addresess are less than 4G... this pool
         * is used by drivers whose hardware can't DMA beyond 32 bits...
         *
         * note that I'm assuming that the page list is ascending and
         * ordered w/r to the physical address
         */
        for (i = 0, num_of_lopages = vm_lopage_poolsize; num_of_lopages && i < pages_initialized; num_of_lopages--, i++) {
                vm_page_t m;

                m = &vm_pages[i];

                if (m->phys_page >= (1 << (32 - PAGE_SHIFT)))
                        panic("couldn't reserve the lopage pool: not enough lo pages\n");

                if (m->phys_page < vm_lopage_poolend)
                        panic("couldn't reserve the lopage pool: page list out of order\n");

                vm_lopage_poolend = m->phys_page;

                if (vm_lopage_poolstart == 0)
                        vm_lopage_poolstart = m->phys_page;
                else {
                        if (m->phys_page < vm_lopage_poolstart)
                                panic("couldn't reserve the lopage pool: page list out of order\n");
                }

                if (fill)
                        fillPage(m->phys_page, fillval);                /* Fill the page with a know value if requested at boot */                      

                vm_page_release(m);
        } 
        last_index = i;

        // -debug code remove
        if (2 == vm_himemory_mode) {
                // free low -> high so high is preferred
                for (i = last_index + 1; i <= pages_initialized; i++) {
                        if(fill) fillPage(vm_pages[i - 1].phys_page, fillval);          /* Fill the page with a know value if requested at boot */                      
                        vm_page_release(&vm_pages[i - 1]);
                }
        }
        else
        // debug code remove-

        /*
         * Release pages in reverse order so that physical pages
         * initially get allocated in ascending addresses. This keeps
         * the devices (which must address physical memory) happy if
         * they require several consecutive pages.
         */
        for (i = pages_initialized; i > last_index; i--) {
                if(fill) fillPage(vm_pages[i - 1].phys_page, fillval);          /* Fill the page with a know value if requested at boot */                      
                vm_page_release(&vm_pages[i - 1]);
        }

#if 0
        {
                vm_page_t xx, xxo, xxl;
                int i, j, k, l;
        
                j = 0;                                                                                                  /* (BRINGUP) */
                xxl = 0;
                
                for( i = 0; i < vm_colors; i++ ) {
                        queue_iterate(&vm_page_queue_free[i],
                                      xx,
                                      vm_page_t,
                                      pageq) {  /* BRINGUP */
                                j++;                                                                                            /* (BRINGUP) */
                                if(j > vm_page_free_count) {                                            /* (BRINGUP) */
                                        panic("pmap_startup: too many pages, xx = %08X, xxl = %08X\n", xx, xxl);
                                }
                                
                                l = vm_page_free_count - j;                                                     /* (BRINGUP) */
                                k = 0;                                                                                          /* (BRINGUP) */
                                
                                if(((j - 1) & 0xFFFF) == 0) kprintf("checking number %d of %d\n", j, vm_page_free_count);

                                for(xxo = xx->pageq.next; xxo != &vm_page_queue_free[i]; xxo = xxo->pageq.next) {       /* (BRINGUP) */
                                        k++;
                                        if(k > l) panic("pmap_startup: too many in secondary check %d %d\n", k, l);
                                        if((xx->phys_page & 0xFFFFFFFF) == (xxo->phys_page & 0xFFFFFFFF)) {     /* (BRINGUP) */
                                                panic("pmap_startup: duplicate physaddr, xx = %08X, xxo = %08X\n", xx, xxo);
                                        }
                                }

                                xxl = xx;
                        }
                }
                
                if(j != vm_page_free_count) {                                           /* (BRINGUP) */
                        panic("pmap_startup: vm_page_free_count does not match, calc =  %d, vm_page_free_count = %08X\n", j, vm_page_free_count);
                }
        }
#endif


        /*
         *      We have to re-align virtual_space_start,
         *      because pmap_steal_memory has been using it.
         */

        virtual_space_start = round_page_32(virtual_space_start);

        *startp = virtual_space_start;
        *endp = virtual_space_end;
}
#endif  /* MACHINE_PAGES */

/*
 *      Routine:        vm_page_module_init
 *      Purpose:
 *              Second initialization pass, to be done after
 *              the basic VM system is ready.
 */
void
vm_page_module_init(void)
{
        vm_page_zone = zinit((vm_size_t) sizeof(struct vm_page),
                             0, PAGE_SIZE, "vm pages");

#if     ZONE_DEBUG
        zone_debug_disable(vm_page_zone);
#endif  /* ZONE_DEBUG */

        zone_change(vm_page_zone, Z_EXPAND, FALSE);
        zone_change(vm_page_zone, Z_EXHAUST, TRUE);
        zone_change(vm_page_zone, Z_FOREIGN, TRUE);

        /*
         * Adjust zone statistics to account for the real pages allocated
         * in vm_page_create(). [Q: is this really what we want?]
         */
        vm_page_zone->count += vm_page_pages;
        vm_page_zone->cur_size += vm_page_pages * vm_page_zone->elem_size;

        mutex_init(&vm_page_alloc_lock, 0);
}

/*
 *      Routine:        vm_page_create
 *      Purpose:
 *              After the VM system is up, machine-dependent code
 *              may stumble across more physical memory.  For example,
 *              memory that it was reserving for a frame buffer.
 *              vm_page_create turns this memory into available pages.
 */

void
vm_page_create(
        ppnum_t start,
        ppnum_t end)
{
        ppnum_t         phys_page;
        vm_page_t       m;

        for (phys_page = start;
             phys_page < end;
             phys_page++) {
                while ((m = (vm_page_t) vm_page_grab_fictitious())
                        == VM_PAGE_NULL)
                        vm_page_more_fictitious();

                vm_page_init(m, phys_page);
                vm_page_pages++;
                vm_page_release(m);
        }
}

/*
 *      vm_page_hash:
 *
 *      Distributes the object/offset key pair among hash buckets.
 *
 *      NOTE:   The bucket count must be a power of 2
 */
#define vm_page_hash(object, offset) (\
        ( (natural_t)((uint32_t)object * vm_page_bucket_hash) + ((uint32_t)atop_64(offset) ^ vm_page_bucket_hash))\
         & vm_page_hash_mask)


/*
 *      vm_page_insert:         [ internal use only ]
 *
 *      Inserts the given mem entry into the object/object-page
 *      table and object list.
 *
 *      The object must be locked.
 */
void
vm_page_insert(
        vm_page_t               mem,
        vm_object_t             object,
        vm_object_offset_t      offset)
{
        vm_page_insert_internal(mem, object, offset, FALSE);
}


void
vm_page_insert_internal(
        vm_page_t               mem,
        vm_object_t             object,
        vm_object_offset_t      offset,
        boolean_t       queues_lock_held)
{
        register vm_page_bucket_t *bucket;

        XPR(XPR_VM_PAGE,
                "vm_page_insert, object 0x%X offset 0x%X page 0x%X\n",
                (integer_t)object, (integer_t)offset, (integer_t)mem, 0,0);

        VM_PAGE_CHECK(mem);

        if (object == vm_submap_object) {
                /* the vm_submap_object is only a placeholder for submaps */
                panic("vm_page_insert(vm_submap_object,0x%llx)\n", offset);
        }

        vm_object_lock_assert_exclusive(object);
#if DEBUG
        if (mem->tabled || mem->object != VM_OBJECT_NULL)
                panic("vm_page_insert: page %p for (obj=%p,off=0x%llx) "
                      "already in (obj=%p,off=0x%llx)",
                      mem, object, offset, mem->object, mem->offset);
#endif
        assert(!object->internal || offset < object->size);

        /* only insert "pageout" pages into "pageout" objects,
         * and normal pages into normal objects */
        assert(object->pageout == mem->pageout);

        assert(vm_page_lookup(object, offset) == VM_PAGE_NULL);

        /*
         *      Record the object/offset pair in this page
         */

        mem->object = object;
        mem->offset = offset;

        /*
         *      Insert it into the object_object/offset hash table
         */

        bucket = &vm_page_buckets[vm_page_hash(object, offset)];
        simple_lock(&vm_page_bucket_lock);
        mem->next = bucket->pages;
        bucket->pages = mem;
#if     MACH_PAGE_HASH_STATS
        if (++bucket->cur_count > bucket->hi_count)
                bucket->hi_count = bucket->cur_count;
#endif /* MACH_PAGE_HASH_STATS */
        simple_unlock(&vm_page_bucket_lock);

        /*
         *      Now link into the object's list of backed pages.
         */

        VM_PAGE_INSERT(mem, object);
        mem->tabled = TRUE;

        /*
         *      Show that the object has one more resident page.
         */

        object->resident_page_count++;

        if (object->purgable == VM_PURGABLE_VOLATILE ||
            object->purgable == VM_PURGABLE_EMPTY) {
                if (queues_lock_held == FALSE)
                        vm_page_lockspin_queues();

                vm_page_purgeable_count++;

                if (queues_lock_held == FALSE)
                        vm_page_unlock_queues();
        }
}

/*
 *      vm_page_replace:
 *
 *      Exactly like vm_page_insert, except that we first
 *      remove any existing page at the given offset in object.
 *
 *      The object and page queues must be locked.
 */

void
vm_page_replace(
        register vm_page_t              mem,
        register vm_object_t            object,
        register vm_object_offset_t     offset)
{
        vm_page_bucket_t *bucket;
        vm_page_t        found_m = VM_PAGE_NULL;

        VM_PAGE_CHECK(mem);
        vm_object_lock_assert_exclusive(object);
#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);

        if (mem->tabled || mem->object != VM_OBJECT_NULL)
                panic("vm_page_replace: page %p for (obj=%p,off=0x%llx) "
                      "already in (obj=%p,off=0x%llx)",
                      mem, object, offset, mem->object, mem->offset);
#endif
        /*
         *      Record the object/offset pair in this page
         */

        mem->object = object;
        mem->offset = offset;

        /*
         *      Insert it into the object_object/offset hash table,
         *      replacing any page that might have been there.
         */

        bucket = &vm_page_buckets[vm_page_hash(object, offset)];
        simple_lock(&vm_page_bucket_lock);

        if (bucket->pages) {
                vm_page_t *mp = &bucket->pages;
                register vm_page_t m = *mp;

                do {
                        if (m->object == object && m->offset == offset) {
                                /*
                                 * Remove old page from hash list
                                 */
                                *mp = m->next;

                                found_m = m;
                                break;
                        }
                        mp = &m->next;
                } while ((m = *mp));

                mem->next = bucket->pages;
        } else {
                mem->next = VM_PAGE_NULL;
        }
        /*
         * insert new page at head of hash list
         */
        bucket->pages = mem;

        simple_unlock(&vm_page_bucket_lock);

        if (found_m) {
                /*
                 * there was already a page at the specified
                 * offset for this object... remove it from
                 * the object and free it back to the free list
                 */
                VM_PAGE_REMOVE(found_m);
                found_m->tabled = FALSE;

                found_m->object = VM_OBJECT_NULL;
                found_m->offset = (vm_object_offset_t) -1;
                object->resident_page_count--;

                if (object->purgable == VM_PURGABLE_VOLATILE ||
                    object->purgable == VM_PURGABLE_EMPTY) {
                        assert(vm_page_purgeable_count > 0);
                        vm_page_purgeable_count--;
                }
                                        
                /*
                 * Return page to the free list.
                 * Note the page is not tabled now
                 */
                vm_page_free(found_m);
        }
        /*
         *      Now link into the object's list of backed pages.
         */

        VM_PAGE_INSERT(mem, object);
        mem->tabled = TRUE;

        /*
         *      And show that the object has one more resident
         *      page.
         */

        object->resident_page_count++;

        if (object->purgable == VM_PURGABLE_VOLATILE ||
            object->purgable == VM_PURGABLE_EMPTY) {
                vm_page_purgeable_count++;
        }
}

/*
 *      vm_page_remove:         [ internal use only ]
 *
 *      Removes the given mem entry from the object/offset-page
 *      table and the object page list.
 *
 *      The object and page queues must be locked.
 */

void
vm_page_remove(
        register vm_page_t      mem)
{
        register vm_page_bucket_t       *bucket;
        register vm_page_t      this;

        XPR(XPR_VM_PAGE,
                "vm_page_remove, object 0x%X offset 0x%X page 0x%X\n",
                (integer_t)mem->object, (integer_t)mem->offset, 
                (integer_t)mem, 0,0);
#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        vm_object_lock_assert_exclusive(mem->object);
        assert(mem->tabled);
        assert(!mem->cleaning);
        VM_PAGE_CHECK(mem);


        /*
         *      Remove from the object_object/offset hash table
         */

        bucket = &vm_page_buckets[vm_page_hash(mem->object, mem->offset)];
        simple_lock(&vm_page_bucket_lock);
        if ((this = bucket->pages) == mem) {
                /* optimize for common case */

                bucket->pages = mem->next;
        } else {
                register vm_page_t      *prev;

                for (prev = &this->next;
                     (this = *prev) != mem;
                     prev = &this->next)
                        continue;
                *prev = this->next;
        }
#if     MACH_PAGE_HASH_STATS
        bucket->cur_count--;
#endif /* MACH_PAGE_HASH_STATS */
        simple_unlock(&vm_page_bucket_lock);

        /*
         *      Now remove from the object's list of backed pages.
         */

        VM_PAGE_REMOVE(mem);

        /*
         *      And show that the object has one fewer resident
         *      page.
         */

        mem->object->resident_page_count--;

        if (mem->object->purgable == VM_PURGABLE_VOLATILE ||
            mem->object->purgable == VM_PURGABLE_EMPTY) {
                assert(vm_page_purgeable_count > 0);
                vm_page_purgeable_count--;
        }
        mem->tabled = FALSE;
        mem->object = VM_OBJECT_NULL;
        mem->offset = (vm_object_offset_t) -1;
}

/*
 *      vm_page_lookup:
 *
 *      Returns the page associated with the object/offset
 *      pair specified; if none is found, VM_PAGE_NULL is returned.
 *
 *      The object must be locked.  No side effects.
 */

unsigned long vm_page_lookup_hint = 0;
unsigned long vm_page_lookup_hint_next = 0;
unsigned long vm_page_lookup_hint_prev = 0;
unsigned long vm_page_lookup_hint_miss = 0;
unsigned long vm_page_lookup_bucket_NULL = 0;
unsigned long vm_page_lookup_miss = 0;


vm_page_t
vm_page_lookup(
        register vm_object_t            object,
        register vm_object_offset_t     offset)
{
        register vm_page_t      mem;
        register vm_page_bucket_t *bucket;
        queue_entry_t           qe;

        vm_object_lock_assert_held(object);
        mem = object->memq_hint;

        if (mem != VM_PAGE_NULL) {
                assert(mem->object == object);

                if (mem->offset == offset) {
                        vm_page_lookup_hint++;
                        return mem;
                }
                qe = queue_next(&mem->listq);

                if (! queue_end(&object->memq, qe)) {
                        vm_page_t       next_page;

                        next_page = (vm_page_t) qe;
                        assert(next_page->object == object);

                        if (next_page->offset == offset) {
                                vm_page_lookup_hint_next++;
                                object->memq_hint = next_page; /* new hint */
                                return next_page;
                        }
                }
                qe = queue_prev(&mem->listq);

                if (! queue_end(&object->memq, qe)) {
                        vm_page_t prev_page;

                        prev_page = (vm_page_t) qe;
                        assert(prev_page->object == object);

                        if (prev_page->offset == offset) {
                                vm_page_lookup_hint_prev++;
                                object->memq_hint = prev_page; /* new hint */
                                return prev_page;
                        }
                }
        }
        /*
         * Search the hash table for this object/offset pair
         */
        bucket = &vm_page_buckets[vm_page_hash(object, offset)];

        /*
         * since we hold the object lock, we are guaranteed that no
         * new pages can be inserted into this object... this in turn
         * guarantess that the page we're looking for can't exist
         * if the bucket it hashes to is currently NULL even when looked
         * at outside the scope of the hash bucket lock... this is a 
         * really cheap optimiztion to avoid taking the lock
         */
        if (bucket->pages == VM_PAGE_NULL) {
                vm_page_lookup_bucket_NULL++;

                return (VM_PAGE_NULL);
        }
        simple_lock(&vm_page_bucket_lock);

        for (mem = bucket->pages; mem != VM_PAGE_NULL; mem = mem->next) {
                VM_PAGE_CHECK(mem);
                if ((mem->object == object) && (mem->offset == offset))
                        break;
        }
        simple_unlock(&vm_page_bucket_lock);

        if (mem != VM_PAGE_NULL) {
                if (object->memq_hint != VM_PAGE_NULL) {
                        vm_page_lookup_hint_miss++;
                }
                assert(mem->object == object);
                object->memq_hint = mem;
        } else
                vm_page_lookup_miss++;

        return(mem);
}


/*
 *      vm_page_rename:
 *
 *      Move the given memory entry from its
 *      current object to the specified target object/offset.
 *
 *      The object must be locked.
 */
void
vm_page_rename(
        register vm_page_t              mem,
        register vm_object_t            new_object,
        vm_object_offset_t              new_offset,
        boolean_t                       encrypted_ok)
{
        assert(mem->object != new_object);

        /*
         * ENCRYPTED SWAP:
         * The encryption key is based on the page's memory object
         * (aka "pager") and paging offset.  Moving the page to
         * another VM object changes its "pager" and "paging_offset"
         * so it has to be decrypted first, or we would lose the key.
         *
         * One exception is VM object collapsing, where we transfer pages
         * from one backing object to its parent object.  This operation also
         * transfers the paging information, so the <pager,paging_offset> info
         * should remain consistent.  The caller (vm_object_do_collapse())
         * sets "encrypted_ok" in this case.
         */
        if (!encrypted_ok && mem->encrypted) {
                panic("vm_page_rename: page %p is encrypted\n", mem);
        }

        /*
         *      Changes to mem->object require the page lock because
         *      the pageout daemon uses that lock to get the object.
         */

        XPR(XPR_VM_PAGE,
                "vm_page_rename, new object 0x%X, offset 0x%X page 0x%X\n",
                (integer_t)new_object, (integer_t)new_offset, 
                (integer_t)mem, 0,0);

        vm_page_lockspin_queues();
        vm_page_remove(mem);
        vm_page_insert(mem, new_object, new_offset);
        vm_page_unlock_queues();
}

/*
 *      vm_page_init:
 *
 *      Initialize the fields in a new page.
 *      This takes a structure with random values and initializes it
 *      so that it can be given to vm_page_release or vm_page_insert.
 */
void
vm_page_init(
        vm_page_t       mem,
        ppnum_t phys_page)
{
        assert(phys_page);
        *mem = vm_page_template;
        mem->phys_page = phys_page;
}

/*
 *      vm_page_grab_fictitious:
 *
 *      Remove a fictitious page from the free list.
 *      Returns VM_PAGE_NULL if there are no free pages.
 */
int     c_vm_page_grab_fictitious = 0;
int     c_vm_page_release_fictitious = 0;
int     c_vm_page_more_fictitious = 0;

extern vm_page_t vm_page_grab_fictitious_common(vm_offset_t phys_addr);

vm_page_t
vm_page_grab_fictitious_common(
        vm_offset_t phys_addr)
{
        register vm_page_t m;

        m = (vm_page_t)zget(vm_page_zone);
        if (m) {
                vm_page_init(m, phys_addr);
                m->fictitious = TRUE;
        }

        c_vm_page_grab_fictitious++;
        return m;
}

vm_page_t
vm_page_grab_fictitious(void)
{
        return vm_page_grab_fictitious_common(vm_page_fictitious_addr);
}

vm_page_t
vm_page_grab_guard(void)
{
        return vm_page_grab_fictitious_common(vm_page_guard_addr);
}

/*
 *      vm_page_release_fictitious:
 *
 *      Release a fictitious page to the free list.
 */

void
vm_page_release_fictitious(
        register vm_page_t m)
{
        assert(!m->free);
        assert(m->busy);
        assert(m->fictitious);
        assert(m->phys_page == vm_page_fictitious_addr ||
               m->phys_page == vm_page_guard_addr);

        c_vm_page_release_fictitious++;
#if DEBUG
        if (m->free)
                panic("vm_page_release_fictitious");
#endif
        m->free = TRUE;
        zfree(vm_page_zone, m);
}

/*
 *      vm_page_more_fictitious:
 *
 *      Add more fictitious pages to the free list.
 *      Allowed to block. This routine is way intimate
 *      with the zones code, for several reasons:
 *      1. we need to carve some page structures out of physical
 *         memory before zones work, so they _cannot_ come from
 *         the zone_map.
 *      2. the zone needs to be collectable in order to prevent
 *         growth without bound. These structures are used by
 *         the device pager (by the hundreds and thousands), as
 *         private pages for pageout, and as blocking pages for
 *         pagein. Temporary bursts in demand should not result in
 *         permanent allocation of a resource.
 *      3. To smooth allocation humps, we allocate single pages
 *         with kernel_memory_allocate(), and cram them into the
 *         zone. This also allows us to initialize the vm_page_t's
 *         on the way into the zone, so that zget() always returns
 *         an initialized structure. The zone free element pointer
 *         and the free page pointer are both the first item in the
 *         vm_page_t.
 *      4. By having the pages in the zone pre-initialized, we need
 *         not keep 2 levels of lists. The garbage collector simply
 *         scans our list, and reduces physical memory usage as it
 *         sees fit.
 */

void vm_page_more_fictitious(void)
{
        register vm_page_t m;
        vm_offset_t addr;
        kern_return_t retval;
        int i;

        c_vm_page_more_fictitious++;

        /*
         * Allocate a single page from the zone_map. Do not wait if no physical
         * pages are immediately available, and do not zero the space. We need
         * our own blocking lock here to prevent having multiple,
         * simultaneous requests from piling up on the zone_map lock. Exactly
         * one (of our) threads should be potentially waiting on the map lock.
         * If winner is not vm-privileged, then the page allocation will fail,
         * and it will temporarily block here in the vm_page_wait().
         */
        mutex_lock(&vm_page_alloc_lock);
        /*
         * If another thread allocated space, just bail out now.
         */
        if (zone_free_count(vm_page_zone) > 5) {
                /*
                 * The number "5" is a small number that is larger than the
                 * number of fictitious pages that any single caller will
                 * attempt to allocate. Otherwise, a thread will attempt to
                 * acquire a fictitious page (vm_page_grab_fictitious), fail,
                 * release all of the resources and locks already acquired,
                 * and then call this routine. This routine finds the pages
                 * that the caller released, so fails to allocate new space.
                 * The process repeats infinitely. The largest known number
                 * of fictitious pages required in this manner is 2. 5 is
                 * simply a somewhat larger number.
                 */
                mutex_unlock(&vm_page_alloc_lock);
                return;
        }

        retval = kernel_memory_allocate(zone_map,
                                        &addr, PAGE_SIZE, VM_PROT_ALL,
                                        KMA_KOBJECT|KMA_NOPAGEWAIT);
        if (retval != KERN_SUCCESS) { 
                /*
                 * No page was available. Tell the pageout daemon, drop the
                 * lock to give another thread a chance at it, and
                 * wait for the pageout daemon to make progress.
                 */
                mutex_unlock(&vm_page_alloc_lock);
                vm_page_wait(THREAD_UNINT);
                return;
        }
        /*
         * Initialize as many vm_page_t's as will fit on this page. This
         * depends on the zone code disturbing ONLY the first item of
         * each zone element.
         */
        m = (vm_page_t)addr;
        for (i = PAGE_SIZE/sizeof(struct vm_page); i > 0; i--) {
                vm_page_init(m, vm_page_fictitious_addr);
                m->fictitious = TRUE;
                m++;
        }
        zcram(vm_page_zone, (void *) addr, PAGE_SIZE);
        mutex_unlock(&vm_page_alloc_lock);
}


/*
 *      vm_pool_low():
 *
 *      Return true if it is not likely that a non-vm_privileged thread
 *      can get memory without blocking.  Advisory only, since the
 *      situation may change under us.
 */
int
vm_pool_low(void)
{
        /* No locking, at worst we will fib. */
        return( vm_page_free_count < vm_page_free_reserved );
}



/*
 * this is an interface to support bring-up of drivers
 * on platforms with physical memory > 4G...
 */
int             vm_himemory_mode = 0;


/*
 * this interface exists to support hardware controllers
 * incapable of generating DMAs with more than 32 bits
 * of address on platforms with physical memory > 4G...
 */
unsigned int    vm_lopage_free_count = 0;
unsigned int    vm_lopage_max_count = 0;
queue_head_t    vm_lopage_queue_free;

vm_page_t
vm_page_grablo(void)
{
        register vm_page_t      mem;
        unsigned int vm_lopage_alloc_count;

        if (vm_lopage_poolsize == 0)
                return (vm_page_grab());

        mutex_lock(&vm_page_queue_free_lock);

        if (! queue_empty(&vm_lopage_queue_free)) {
                queue_remove_first(&vm_lopage_queue_free,
                                   mem,
                                   vm_page_t,
                                   pageq);
                assert(mem->free);
                assert(mem->busy);
                assert(!mem->pmapped);
                assert(!mem->wpmapped);

                mem->pageq.next = NULL;
                mem->pageq.prev = NULL;
                mem->free = FALSE;

                vm_lopage_free_count--;
                vm_lopage_alloc_count = (vm_lopage_poolend - vm_lopage_poolstart) - vm_lopage_free_count;
                if (vm_lopage_alloc_count > vm_lopage_max_count)
                        vm_lopage_max_count = vm_lopage_alloc_count;
        } else {
                mem = VM_PAGE_NULL;
        }
        mutex_unlock(&vm_page_queue_free_lock);

        return (mem);
}


/*
 *      vm_page_grab:
 *
 *      first try to grab a page from the per-cpu free list...
 *      this must be done while pre-emption is disabled... if
 *      a page is available, we're done... 
 *      if no page is available, grab the vm_page_queue_free_lock
 *      and see if current number of free pages would allow us
 *      to grab at least 1... if not, return VM_PAGE_NULL as before... 
 *      if there are pages available, disable preemption and
 *      recheck the state of the per-cpu free list... we could
 *      have been preempted and moved to a different cpu, or
 *      some other thread could have re-filled it... if still
 *      empty, figure out how many pages we can steal from the
 *      global free queue and move to the per-cpu queue...
 *      return 1 of these pages when done... only wakeup the
 *      pageout_scan thread if we moved pages from the global
 *      list... no need for the wakeup if we've satisfied the
 *      request from the per-cpu queue.
 */

#define COLOR_GROUPS_TO_STEAL   4


vm_page_t
vm_page_grab( void )
{
        vm_page_t       mem;


        disable_preemption();

        if ((mem = PROCESSOR_DATA(current_processor(), free_pages))) {
return_page_from_cpu_list:
                PROCESSOR_DATA(current_processor(), page_grab_count) += 1;
                PROCESSOR_DATA(current_processor(), free_pages) = mem->pageq.next;
                mem->pageq.next = NULL;

                enable_preemption();

                assert(mem->listq.next == NULL && mem->listq.prev == NULL);
                assert(mem->tabled == FALSE);
                assert(mem->object == VM_OBJECT_NULL);
                assert(!mem->laundry);
                assert(!mem->free);
                assert(pmap_verify_free(mem->phys_page));
                assert(mem->busy);
                assert(!mem->encrypted);
                assert(!mem->pmapped);
                assert(!mem->wpmapped);

                return mem;
        }
        enable_preemption();


        mutex_lock(&vm_page_queue_free_lock);

        /*
         *      Optionally produce warnings if the wire or gobble
         *      counts exceed some threshold.
         */
        if (vm_page_wire_count_warning > 0
            && vm_page_wire_count >= vm_page_wire_count_warning) {
                printf("mk: vm_page_grab(): high wired page count of %d\n",
                        vm_page_wire_count);
                assert(vm_page_wire_count < vm_page_wire_count_warning);
        }
        if (vm_page_gobble_count_warning > 0
            && vm_page_gobble_count >= vm_page_gobble_count_warning) {
                printf("mk: vm_page_grab(): high gobbled page count of %d\n",
                        vm_page_gobble_count);
                assert(vm_page_gobble_count < vm_page_gobble_count_warning);
        }

        /*
         *      Only let privileged threads (involved in pageout)
         *      dip into the reserved pool.
         */
        if ((vm_page_free_count < vm_page_free_reserved) &&
            !(current_thread()->options & TH_OPT_VMPRIV)) {
                mutex_unlock(&vm_page_queue_free_lock);
                mem = VM_PAGE_NULL;
        }
        else {
               vm_page_t        head;
               vm_page_t        tail;
               unsigned int     pages_to_steal;
               unsigned int     color;

               while ( vm_page_free_count == 0 ) {

                        mutex_unlock(&vm_page_queue_free_lock);
                        /*
                         * must be a privileged thread to be
                         * in this state since a non-privileged 
                         * thread would have bailed if we were
                         * under the vm_page_free_reserved mark
                         */
                        VM_PAGE_WAIT();
                        mutex_lock(&vm_page_queue_free_lock);
                }

                disable_preemption();

                if ((mem = PROCESSOR_DATA(current_processor(), free_pages))) {
                        mutex_unlock(&vm_page_queue_free_lock);

                        /*
                         * we got preempted and moved to another processor
                         * or we got preempted and someone else ran and filled the cache
                         */
                        goto return_page_from_cpu_list;
                }
                if (vm_page_free_count <= vm_page_free_reserved)
                        pages_to_steal = 1;
                else {
                        pages_to_steal = COLOR_GROUPS_TO_STEAL * vm_colors;
                
                        if (pages_to_steal > (vm_page_free_count - vm_page_free_reserved))
                                pages_to_steal = (vm_page_free_count - vm_page_free_reserved);
                }
                color = PROCESSOR_DATA(current_processor(), start_color);
                head = tail = NULL;

                while (pages_to_steal--) {
                        if (--vm_page_free_count < vm_page_free_count_minimum)
                                vm_page_free_count_minimum = vm_page_free_count;

                        while (queue_empty(&vm_page_queue_free[color]))
                                color = (color + 1) & vm_color_mask;
                
                        queue_remove_first(&vm_page_queue_free[color],
                                           mem,
                                           vm_page_t,
                                           pageq);
                        mem->pageq.next = NULL;
                        mem->pageq.prev = NULL;

                        color = (color + 1) & vm_color_mask;

                        if (head == NULL)
                                head = mem;
                        else
                                tail->pageq.next = (queue_t)mem;
                        tail = mem;

                        mem->pageq.prev = NULL;
                        assert(mem->listq.next == NULL && mem->listq.prev == NULL);
                        assert(mem->tabled == FALSE);
                        assert(mem->object == VM_OBJECT_NULL);
                        assert(!mem->laundry);
                        assert(mem->free);
                        mem->free = FALSE;

                        assert(pmap_verify_free(mem->phys_page));
                        assert(mem->busy);
                        assert(!mem->free);
                        assert(!mem->encrypted);
                        assert(!mem->pmapped);
                        assert(!mem->wpmapped);
                }
                PROCESSOR_DATA(current_processor(), free_pages) = head->pageq.next;
                PROCESSOR_DATA(current_processor(), start_color) = color;

                /*
                 * satisfy this request
                 */
                PROCESSOR_DATA(current_processor(), page_grab_count) += 1;
                mem = head;
                mem->pageq.next = NULL;

                mutex_unlock(&vm_page_queue_free_lock);

                enable_preemption();
        }
        /*
         *      Decide if we should poke the pageout daemon.
         *      We do this if the free count is less than the low
         *      water mark, or if the free count is less than the high
         *      water mark (but above the low water mark) and the inactive
         *      count is less than its target.
         *
         *      We don't have the counts locked ... if they change a little,
         *      it doesn't really matter.
         */
        if ((vm_page_free_count < vm_page_free_min) ||
            ((vm_page_free_count < vm_page_free_target) &&
             ((vm_page_inactive_count + vm_page_speculative_count) < vm_page_inactive_min)))
                thread_wakeup((event_t) &vm_page_free_wanted);

#if CONFIG_EMBEDDED
        {
        int     percent_avail;

        /*
         * Decide if we need to poke the memorystatus notification thread.
         */
        percent_avail = 
                (vm_page_active_count + vm_page_inactive_count + 
                 vm_page_speculative_count + vm_page_free_count +
                 vm_page_purgeable_count ) * 100 /
                atop_64(max_mem);
        if (percent_avail <= (kern_memorystatus_level - 5)) {
                kern_memorystatus_level = percent_avail;
                thread_wakeup((event_t)&kern_memorystatus_wakeup);
        }
        }
#endif

//      dbgLog(mem->phys_page, vm_page_free_count, vm_page_wire_count, 4);      /* (TEST/DEBUG) */

        return mem;
}

/*
 *      vm_page_release:
 *
 *      Return a page to the free list.
 */

void
vm_page_release(
        register vm_page_t      mem)
{
        unsigned int    color;
#if 0
        unsigned int pindex;
        phys_entry *physent;

        physent = mapping_phys_lookup(mem->phys_page, &pindex);         /* (BRINGUP) */
        if(physent->ppLink & ppN) {                                                                                     /* (BRINGUP) */
                panic("vm_page_release: already released - %08X %08X\n", mem, mem->phys_page);
        }
        physent->ppLink = physent->ppLink | ppN;                                                        /* (BRINGUP) */
#endif
        assert(!mem->private && !mem->fictitious);

//      dbgLog(mem->phys_page, vm_page_free_count, vm_page_wire_count, 5);      /* (TEST/DEBUG) */

        mutex_lock(&vm_page_queue_free_lock);
#if DEBUG
        if (mem->free)
                panic("vm_page_release");
#endif
        mem->free = TRUE;

        assert(mem->busy);
        assert(!mem->laundry);
        assert(mem->object == VM_OBJECT_NULL);
        assert(mem->pageq.next == NULL &&
               mem->pageq.prev == NULL);
        assert(mem->listq.next == NULL &&
               mem->listq.prev == NULL);
        
        if (mem->phys_page <= vm_lopage_poolend && mem->phys_page >= vm_lopage_poolstart) {
                /*
                 * this exists to support hardware controllers
                 * incapable of generating DMAs with more than 32 bits
                 * of address on platforms with physical memory > 4G...
                 */
                queue_enter_first(&vm_lopage_queue_free,
                                  mem,
                                  vm_page_t,
                                  pageq);
                vm_lopage_free_count++;
        } else {          
                color = mem->phys_page & vm_color_mask;
                queue_enter_first(&vm_page_queue_free[color],
                                  mem,
                                  vm_page_t,
                                  pageq);
                vm_page_free_count++;
                /*
                 *      Check if we should wake up someone waiting for page.
                 *      But don't bother waking them unless they can allocate.
                 *
                 *      We wakeup only one thread, to prevent starvation.
                 *      Because the scheduling system handles wait queues FIFO,
                 *      if we wakeup all waiting threads, one greedy thread
                 *      can starve multiple niceguy threads.  When the threads
                 *      all wakeup, the greedy threads runs first, grabs the page,
                 *      and waits for another page.  It will be the first to run
                 *      when the next page is freed.
                 *
                 *      However, there is a slight danger here.
                 *      The thread we wake might not use the free page.
                 *      Then the other threads could wait indefinitely
                 *      while the page goes unused.  To forestall this,
                 *      the pageout daemon will keep making free pages
                 *      as long as vm_page_free_wanted is non-zero.
                 */

                if ((vm_page_free_wanted_privileged > 0) && vm_page_free_count) {
                        vm_page_free_wanted_privileged--;
                        thread_wakeup_one((event_t) &vm_page_free_wanted_privileged);
                } else if ((vm_page_free_wanted > 0) &&
                           (vm_page_free_count >= vm_page_free_reserved)) {
                        vm_page_free_wanted--;
                        thread_wakeup_one((event_t) &vm_page_free_count);
                }
        }
        mutex_unlock(&vm_page_queue_free_lock);

#if CONFIG_EMBEDDED
        {
        int     percent_avail;

        /*
         * Decide if we need to poke the memorystatus notification thread.
         * Locking is not a big issue, as only a single thread delivers these.
         */
        percent_avail = 
                (vm_page_active_count + vm_page_inactive_count + 
                 vm_page_speculative_count + vm_page_free_count +
                 vm_page_purgeable_count ) * 100 /
                atop_64(max_mem);
        if (percent_avail >= (kern_memorystatus_level + 5)) {
                kern_memorystatus_level = percent_avail;
                thread_wakeup((event_t)&kern_memorystatus_wakeup);
        }
        }
#endif
}

/*
 *      vm_page_wait:
 *
 *      Wait for a page to become available.
 *      If there are plenty of free pages, then we don't sleep.
 *
 *      Returns:
 *              TRUE:  There may be another page, try again
 *              FALSE: We were interrupted out of our wait, don't try again
 */

boolean_t
vm_page_wait(
        int     interruptible )
{
        /*
         *      We can't use vm_page_free_reserved to make this
         *      determination.  Consider: some thread might
         *      need to allocate two pages.  The first allocation
         *      succeeds, the second fails.  After the first page is freed,
         *      a call to vm_page_wait must really block.
         */
        kern_return_t   wait_result;
        int             need_wakeup = 0;
        int             is_privileged = current_thread()->options & TH_OPT_VMPRIV;

        mutex_lock(&vm_page_queue_free_lock);

        if (is_privileged && vm_page_free_count) {
                mutex_unlock(&vm_page_queue_free_lock);
                return TRUE;
        }
        if (vm_page_free_count < vm_page_free_target) {

                if (is_privileged) {
                        if (vm_page_free_wanted_privileged++ == 0)
                                need_wakeup = 1;
                        wait_result = assert_wait((event_t)&vm_page_free_wanted_privileged, interruptible);
                } else {
                        if (vm_page_free_wanted++ == 0)
                                need_wakeup = 1;
                        wait_result = assert_wait((event_t)&vm_page_free_count, interruptible);
                }
                mutex_unlock(&vm_page_queue_free_lock);
                counter(c_vm_page_wait_block++);

                if (need_wakeup)
                        thread_wakeup((event_t)&vm_page_free_wanted);

                if (wait_result == THREAD_WAITING)
                        wait_result = thread_block(THREAD_CONTINUE_NULL);

                return(wait_result == THREAD_AWAKENED);
        } else {
                mutex_unlock(&vm_page_queue_free_lock);
                return TRUE;
        }
}

/*
 *      vm_page_alloc:
 *
 *      Allocate and return a memory cell associated
 *      with this VM object/offset pair.
 *
 *      Object must be locked.
 */

vm_page_t
vm_page_alloc(
        vm_object_t             object,
        vm_object_offset_t      offset)
{
        register vm_page_t      mem;

        vm_object_lock_assert_exclusive(object);
        mem = vm_page_grab();
        if (mem == VM_PAGE_NULL)
                return VM_PAGE_NULL;

        vm_page_insert(mem, object, offset);

        return(mem);
}

vm_page_t
vm_page_alloclo(
        vm_object_t             object,
        vm_object_offset_t      offset)
{
        register vm_page_t      mem;

        vm_object_lock_assert_exclusive(object);
        mem = vm_page_grablo();
        if (mem == VM_PAGE_NULL)
                return VM_PAGE_NULL;

        vm_page_insert(mem, object, offset);

        return(mem);
}


/*
 *      vm_page_alloc_guard:
 *      
 *      Allocate a ficticious page which will be used
 *      as a guard page.  The page will be inserted into
 *      the object and returned to the caller.
 */

vm_page_t
vm_page_alloc_guard(
        vm_object_t             object,
        vm_object_offset_t      offset)
{
        register vm_page_t      mem;

        vm_object_lock_assert_exclusive(object);
        mem = vm_page_grab_guard();
        if (mem == VM_PAGE_NULL)
                return VM_PAGE_NULL;

        vm_page_insert(mem, object, offset);

        return(mem);
}


counter(unsigned int c_laundry_pages_freed = 0;)

boolean_t       vm_page_free_verify = TRUE;
/*
 *      vm_page_free:
 *
 *      Returns the given page to the free list,
 *      disassociating it with any VM object.
 *
 *      Object and page queues must be locked prior to entry.
 */
void
vm_page_free_prepare(
        register vm_page_t      mem)
{
        VM_PAGE_CHECK(mem);
        assert(!mem->free);
        assert(!mem->cleaning);
        assert(!mem->pageout);

#if DEBUG
        if (vm_page_free_verify && !mem->fictitious && !mem->private) {
                assert(pmap_verify_free(mem->phys_page));
        }
        if (mem->object)
                vm_object_lock_assert_exclusive(mem->object);
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);

        if (mem->free)
               panic("vm_page_free: freeing page on free list\n");
#endif

        if (mem->laundry) {
                /*
                 * We may have to free a page while it's being laundered
                 * if we lost its pager (due to a forced unmount, for example).
                 * We need to call vm_pageout_throttle_up() before removing
                 * the page from its VM object, so that we can find out on
                 * which pageout queue the page is.
                 */
                vm_pageout_throttle_up(mem);
                counter(++c_laundry_pages_freed);
        }

        if (mem->tabled)
                vm_page_remove(mem);    /* clears tabled, object, offset */

        VM_PAGE_QUEUES_REMOVE(mem);     /* clears active/inactive/throttled/speculative */

        if (mem->wire_count) {
                if (!mem->private && !mem->fictitious)
                        vm_page_wire_count--;
                mem->wire_count = 0;
                assert(!mem->gobbled);
        } else if (mem->gobbled) {
                if (!mem->private && !mem->fictitious)
                        vm_page_wire_count--;
                vm_page_gobble_count--;
        }
        mem->gobbled = FALSE;

        PAGE_WAKEUP(mem);       /* clears wanted */

        /* Some of these may be unnecessary */
        mem->busy = TRUE;
        mem->absent = FALSE;
        mem->error = FALSE;
        mem->dirty = FALSE;
        mem->precious = FALSE;
        mem->reference = FALSE;
        mem->encrypted = FALSE;
        mem->encrypted_cleaning = FALSE;
        mem->deactivated = FALSE;
        mem->pmapped = FALSE;
        mem->wpmapped = FALSE;

        if (mem->private) {
                mem->private = FALSE;
                mem->fictitious = TRUE;
                mem->phys_page = vm_page_fictitious_addr;
        }
        if (!mem->fictitious) {
                if (mem->zero_fill == TRUE) {
                        mem->zero_fill = FALSE;
                        OSAddAtomic(-1, (SInt32 *)&vm_zf_count);
                }
                vm_page_init(mem, mem->phys_page);
        }
}

void
vm_page_free(
        vm_page_t       mem)
{
        vm_page_free_prepare(mem);      
        if (mem->fictitious) {
                vm_page_release_fictitious(mem);
        } else {
                vm_page_release(mem);
        }
}

/*
 * Free a list of pages.  The list can be up to several hundred pages,
 * as blocked up by vm_pageout_scan().
 * The big win is not having to take the page q and free list locks once
 * per page.  We sort the incoming pages into n lists, one for
 * each color.
 *
 * The page queues must be locked, and are kept locked.
 */
void
vm_page_free_list(
        vm_page_t       mem)
{
        vm_page_t       nxt;
        int             pg_count = 0;
        int             color;
        int             inuse_list_head = -1;

        queue_head_t    free_list[MAX_COLORS];
        int             inuse[MAX_COLORS];

        for (color = 0; color < (signed) vm_colors; color++) {
                queue_init(&free_list[color]);
        }
        
#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        while (mem) {
#if DEBUG
                if (mem->tabled || mem->object)
                        panic("vm_page_free_list: freeing tabled page\n");
                if (mem->inactive || mem->active || mem->throttled || mem->free)
                        panic("vm_page_free_list: freeing page on list\n");
                if (vm_page_free_verify && !mem->fictitious && !mem->private) {
                        assert(pmap_verify_free(mem->phys_page));
                }
#endif
                assert(mem->pageq.prev == NULL);
                assert(mem->busy);
                assert(!mem->free);
                nxt = (vm_page_t)(mem->pageq.next);

                if (!mem->fictitious) {
                        mem->free = TRUE;

                        color = mem->phys_page & vm_color_mask;
                        if (queue_empty(&free_list[color])) {
                                inuse[color] = inuse_list_head;
                                inuse_list_head = color;
                        }
                        queue_enter_first(&free_list[color],
                                          mem,
                                          vm_page_t,
                                          pageq);
                        pg_count++;
                } else {
                        assert(mem->phys_page == vm_page_fictitious_addr ||
                               mem->phys_page == vm_page_guard_addr);
                        vm_page_release_fictitious(mem);
                }
                mem = nxt;
        }
        if (pg_count) {
                unsigned int    avail_free_count;
          
                mutex_lock(&vm_page_queue_free_lock);

                color = inuse_list_head;
                
                while( color != -1 ) {
                        vm_page_t first, last;
                        vm_page_t first_free;

                        first = (vm_page_t) queue_first(&free_list[color]);
                        last = (vm_page_t) queue_last(&free_list[color]);
                        first_free = (vm_page_t) queue_first(&vm_page_queue_free[color]);

                        if (queue_empty(&vm_page_queue_free[color])) {
                                queue_last(&vm_page_queue_free[color]) =
                                        (queue_entry_t) last;
                        } else {
                                queue_prev(&first_free->pageq) =
                                        (queue_entry_t) last;
                        }
                        queue_first(&vm_page_queue_free[color]) =
                                (queue_entry_t) first;
                        queue_prev(&first->pageq) =
                                (queue_entry_t) &vm_page_queue_free[color];
                        queue_next(&last->pageq) =
                                (queue_entry_t) first_free;
                        color = inuse[color];
                }
                
                vm_page_free_count += pg_count;
                avail_free_count = vm_page_free_count;

                while ((vm_page_free_wanted_privileged > 0) && avail_free_count) {
                        vm_page_free_wanted_privileged--;
                        avail_free_count--;

                        thread_wakeup_one((event_t) &vm_page_free_wanted_privileged);
                }

                if ((vm_page_free_wanted > 0) &&
                    (avail_free_count >= vm_page_free_reserved)) {
                        unsigned int  available_pages;

                        if (avail_free_count >= vm_page_free_reserved) {
                                available_pages = (avail_free_count - vm_page_free_reserved);
                        } else {
                                available_pages = 0;
                        }

                        if (available_pages >= vm_page_free_wanted) {
                                vm_page_free_wanted = 0;
                                thread_wakeup((event_t) &vm_page_free_count);
                        } else {
                                while (available_pages--) {
                                        vm_page_free_wanted--;
                                        thread_wakeup_one((event_t) &vm_page_free_count);
                                }
                        }
                }
                mutex_unlock(&vm_page_queue_free_lock);

#if CONFIG_EMBEDDED
                {
                int percent_avail;

                /*
                 * Decide if we need to poke the memorystatus notification thread.
                 */
                percent_avail = 
                        (vm_page_active_count + vm_page_inactive_count + 
                         vm_page_speculative_count + vm_page_free_count +
                         vm_page_purgeable_count ) * 100 /
                        atop_64(max_mem);
                if (percent_avail >= (kern_memorystatus_level + 5)) {
                        kern_memorystatus_level = percent_avail;
                        thread_wakeup((event_t)&kern_memorystatus_wakeup);
                }
                }
#endif
        }
}


/*
 *      vm_page_wire:
 *
 *      Mark this page as wired down by yet
 *      another map, removing it from paging queues
 *      as necessary.
 *
 *      The page's object and the page queues must be locked.
 */
void
vm_page_wire(
        register vm_page_t      mem)
{

//      dbgLog(current_thread(), mem->offset, mem->object, 1);  /* (TEST/DEBUG) */

        VM_PAGE_CHECK(mem);
#if DEBUG
        if (mem->object)
                vm_object_lock_assert_exclusive(mem->object);
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        if (mem->wire_count == 0) {
                VM_PAGE_QUEUES_REMOVE(mem);
                if (!mem->private && !mem->fictitious && !mem->gobbled)
                        vm_page_wire_count++;
                if (mem->gobbled)
                        vm_page_gobble_count--;
                mem->gobbled = FALSE;
                if (mem->zero_fill == TRUE) {
                        mem->zero_fill = FALSE;
                        OSAddAtomic(-1, (SInt32 *)&vm_zf_count);
                }
                /* 
                 * ENCRYPTED SWAP:
                 * The page could be encrypted, but
                 * We don't have to decrypt it here
                 * because we don't guarantee that the
                 * data is actually valid at this point.
                 * The page will get decrypted in
                 * vm_fault_wire() if needed.
                 */
        }
        assert(!mem->gobbled);
        mem->wire_count++;
}

/*
 *      vm_page_gobble:
 *
 *      Mark this page as consumed by the vm/ipc/xmm subsystems.
 *
 *      Called only for freshly vm_page_grab()ed pages - w/ nothing locked.
 */
void
vm_page_gobble(
        register vm_page_t      mem)
{
        vm_page_lockspin_queues();
        VM_PAGE_CHECK(mem);

        assert(!mem->gobbled);
        assert(mem->wire_count == 0);

        if (!mem->gobbled && mem->wire_count == 0) {
                if (!mem->private && !mem->fictitious)
                        vm_page_wire_count++;
        }
        vm_page_gobble_count++;
        mem->gobbled = TRUE;
        vm_page_unlock_queues();
}

/*
 *      vm_page_unwire:
 *
 *      Release one wiring of this page, potentially
 *      enabling it to be paged again.
 *
 *      The page's object and the page queues must be locked.
 */
void
vm_page_unwire(
        register vm_page_t      mem)
{

//      dbgLog(current_thread(), mem->offset, mem->object, 0);  /* (TEST/DEBUG) */

        VM_PAGE_CHECK(mem);
        assert(mem->wire_count > 0);
#if DEBUG
        if (mem->object)
                vm_object_lock_assert_exclusive(mem->object);
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        if (--mem->wire_count == 0) {
                assert(!mem->private && !mem->fictitious);
                vm_page_wire_count--;
                assert(!mem->laundry);
                assert(mem->object != kernel_object);
                assert(mem->pageq.next == NULL && mem->pageq.prev == NULL);
                if (!IP_VALID(memory_manager_default) && 
                        mem->dirty && mem->object->internal && 
                        (mem->object->purgable == VM_PURGABLE_DENY ||
                         mem->object->purgable == VM_PURGABLE_NONVOLATILE)) {
                        queue_enter(&vm_page_queue_throttled, mem, vm_page_t, pageq);
                        vm_page_throttled_count++;
                        mem->throttled = TRUE;
                } else {
                        queue_enter(&vm_page_queue_active, mem, vm_page_t, pageq);
                        vm_page_active_count++;
                        mem->active = TRUE;
                }
                mem->reference = TRUE;
        }
}


/*
 *      vm_page_deactivate:
 *
 *      Returns the given page to the inactive list,
 *      indicating that no physical maps have access
 *      to this page.  [Used by the physical mapping system.]
 *
 *      The page queues must be locked.
 */
void
vm_page_deactivate(
        register vm_page_t      m)
{
        boolean_t rapid_age = FALSE;

        VM_PAGE_CHECK(m);
        assert(m->object != kernel_object);
        assert(m->phys_page != vm_page_guard_addr);

//      dbgLog(m->phys_page, vm_page_free_count, vm_page_wire_count, 6);        /* (TEST/DEBUG) */
#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        /*
         *      This page is no longer very interesting.  If it was
         *      interesting (active or inactive/referenced), then we
         *      clear the reference bit and (re)enter it in the
         *      inactive queue.  Note wired pages should not have
         *      their reference bit cleared.
         */
        if (m->gobbled) {               /* can this happen? */
                assert(m->wire_count == 0);

                if (!m->private && !m->fictitious)
                        vm_page_wire_count--;
                vm_page_gobble_count--;
                m->gobbled = FALSE;
        }
        if (m->private || (m->wire_count != 0))
                return;

        if (m->active && m->deactivated == TRUE) {
                if (!pmap_is_referenced(m->phys_page))
                        rapid_age = TRUE;
        }
        if (rapid_age == FALSE && !m->fictitious && !m->absent)
                pmap_clear_reference(m->phys_page);

        m->reference = FALSE;
        m->deactivated = FALSE;
        m->no_cache = FALSE;

        if (!m->inactive) {
                VM_PAGE_QUEUES_REMOVE(m);

                assert(!m->laundry);
                assert(m->pageq.next == NULL && m->pageq.prev == NULL);

                if (!IP_VALID(memory_manager_default) &&
                        m->dirty && m->object->internal &&
                        (m->object->purgable == VM_PURGABLE_DENY ||
                         m->object->purgable == VM_PURGABLE_NONVOLATILE)) {
                        queue_enter(&vm_page_queue_throttled, m, vm_page_t, pageq);
                        m->throttled = TRUE;
                        vm_page_throttled_count++;
                } else {
                        if (rapid_age == TRUE ||
                            (!m->fictitious && m->object->named && m->object->ref_count == 1)) {
                                vm_page_speculate(m, FALSE);
                                vm_page_speculative_recreated++;
                                return;
                        } else {
                                if (m->zero_fill) {
                                        queue_enter(&vm_page_queue_zf, m, vm_page_t, pageq);
                                        vm_zf_queue_count++;
                                } else {
                                        queue_enter(&vm_page_queue_inactive, m, vm_page_t, pageq);
                                }
                        }
                        m->inactive = TRUE;
                        if (!m->fictitious) {
                                vm_page_inactive_count++;
                                token_new_pagecount++;
                        }
                }
        }
}

/*
 *      vm_page_activate:
 *
 *      Put the specified page on the active list (if appropriate).
 *
 *      The page queues must be locked.
 */

void
vm_page_activate(
        register vm_page_t      m)
{
        VM_PAGE_CHECK(m);
#ifdef  FIXME_4778297
        assert(m->object != kernel_object);
#endif
        assert(m->phys_page != vm_page_guard_addr);
#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        if (m->gobbled) {
                assert(m->wire_count == 0);
                if (!m->private && !m->fictitious)
                        vm_page_wire_count--;
                vm_page_gobble_count--;
                m->gobbled = FALSE;
        }
        if (m->private)
                return;

#if DEBUG
        if (m->active)
                panic("vm_page_activate: already active");
#endif

        if (m->speculative) {
                DTRACE_VM2(pgrec, int, 1, (uint64_t *), NULL);
                DTRACE_VM2(pgfrec, int, 1, (uint64_t *), NULL);
        }

        VM_PAGE_QUEUES_REMOVE(m);

        if (m->wire_count == 0) {
                assert(!m->laundry);
                assert(m->pageq.next == NULL && m->pageq.prev == NULL);
                if (!IP_VALID(memory_manager_default) && 
                        !m->fictitious && m->dirty && m->object->internal && 
                        (m->object->purgable == VM_PURGABLE_DENY ||
                         m->object->purgable == VM_PURGABLE_NONVOLATILE)) {
                        queue_enter(&vm_page_queue_throttled, m, vm_page_t, pageq);
                        m->throttled = TRUE;
                        vm_page_throttled_count++;
                } else {
                        queue_enter(&vm_page_queue_active, m, vm_page_t, pageq);
                        m->active = TRUE;
                        if (!m->fictitious)
                                vm_page_active_count++;
                }
                m->reference = TRUE;
                m->no_cache = FALSE;
        }
}


/*
 *      vm_page_speculate:
 *
 *      Put the specified page on the speculative list (if appropriate).
 *
 *      The page queues must be locked.
 */
void
vm_page_speculate(
        vm_page_t       m,
        boolean_t       new)
{
        struct vm_speculative_age_q     *aq;

        VM_PAGE_CHECK(m);
        assert(m->object != kernel_object);
        assert(!m->speculative && !m->active && !m->inactive && !m->throttled);
        assert(m->phys_page != vm_page_guard_addr);
        assert(m->pageq.next == NULL && m->pageq.prev == NULL);
#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        if (m->wire_count == 0) {
                mach_timespec_t         ts;

                clock_get_system_nanotime(&ts.tv_sec, (unsigned *)&ts.tv_nsec);

                if (vm_page_speculative_count == 0) {

                        speculative_age_index = VM_PAGE_MIN_SPECULATIVE_AGE_Q;
                        speculative_steal_index = VM_PAGE_MIN_SPECULATIVE_AGE_Q;

                        aq = &vm_page_queue_speculative[speculative_age_index];

                        /*
                         * set the timer to begin a new group
                         */
                        aq->age_ts.tv_sec = VM_PAGE_SPECULATIVE_Q_AGE_MS / 1000;
                        aq->age_ts.tv_nsec = (VM_PAGE_SPECULATIVE_Q_AGE_MS % 1000) * 1000 * NSEC_PER_USEC;

                        ADD_MACH_TIMESPEC(&aq->age_ts, &ts);
                } else {
                        aq = &vm_page_queue_speculative[speculative_age_index];

                        if (CMP_MACH_TIMESPEC(&ts, &aq->age_ts) >= 0) {

                                speculative_age_index++;

                                if (speculative_age_index > VM_PAGE_MAX_SPECULATIVE_AGE_Q)
                                        speculative_age_index = VM_PAGE_MIN_SPECULATIVE_AGE_Q;
                                if (speculative_age_index == speculative_steal_index) {
                                        speculative_steal_index = speculative_age_index + 1;

                                        if (speculative_steal_index > VM_PAGE_MAX_SPECULATIVE_AGE_Q)
                                                speculative_steal_index = VM_PAGE_MIN_SPECULATIVE_AGE_Q;
                                }
                                aq = &vm_page_queue_speculative[speculative_age_index];

                                if (!queue_empty(&aq->age_q))
                                        vm_page_speculate_ageit(aq);

                                aq->age_ts.tv_sec = VM_PAGE_SPECULATIVE_Q_AGE_MS / 1000;
                                aq->age_ts.tv_nsec = (VM_PAGE_SPECULATIVE_Q_AGE_MS % 1000) * 1000 * NSEC_PER_USEC;

                                ADD_MACH_TIMESPEC(&aq->age_ts, &ts);
                        }
                }
                enqueue_tail(&aq->age_q, &m->pageq);
                m->speculative = TRUE;
                vm_page_speculative_count++;

                if (new == TRUE) {
                        m->object->pages_created++;
                        vm_page_speculative_created++;
                }
        }
}


/*
 * move pages from the specified aging bin to
 * the speculative bin that pageout_scan claims from
 *
 *      The page queues must be locked.
 */
void
vm_page_speculate_ageit(struct vm_speculative_age_q *aq)
{
        struct vm_speculative_age_q     *sq;
        vm_page_t       t;

        sq = &vm_page_queue_speculative[VM_PAGE_SPECULATIVE_AGED_Q];

        if (queue_empty(&sq->age_q)) {
                sq->age_q.next = aq->age_q.next;
                sq->age_q.prev = aq->age_q.prev;
                
                t = (vm_page_t)sq->age_q.next;
                t->pageq.prev = &sq->age_q;

                t = (vm_page_t)sq->age_q.prev;
                t->pageq.next = &sq->age_q;
        } else {
                t = (vm_page_t)sq->age_q.prev;
                t->pageq.next = aq->age_q.next;
                                                
                t = (vm_page_t)aq->age_q.next;
                t->pageq.prev = sq->age_q.prev;

                t = (vm_page_t)aq->age_q.prev;
                t->pageq.next = &sq->age_q;

                sq->age_q.prev = aq->age_q.prev;
        }
        queue_init(&aq->age_q);
}


void
vm_page_lru(
        vm_page_t       m)
{
        VM_PAGE_CHECK(m);
        assert(m->object != kernel_object);
        assert(m->phys_page != vm_page_guard_addr);

#if DEBUG
        _mutex_assert(&vm_page_queue_lock, MA_OWNED);
#endif
        if (m->active || m->reference)
                return;

        if (m->private || (m->wire_count != 0))
                return;

        m->no_cache = FALSE;

        VM_PAGE_QUEUES_REMOVE(m);

        assert(!m->laundry);
        assert(m->pageq.next == NULL && m->pageq.prev == NULL);

        queue_enter(&vm_page_queue_inactive, m, vm_page_t, pageq);
        m->inactive = TRUE;

        vm_page_inactive_count++;
        token_new_pagecount++;
}


/*
 *      vm_page_part_zero_fill:
 *
 *      Zero-fill a part of the page.
 */
void
vm_page_part_zero_fill(
        vm_page_t       m,
        vm_offset_t     m_pa,
        vm_size_t       len)
{
        vm_page_t       tmp;

        VM_PAGE_CHECK(m);
#ifdef PMAP_ZERO_PART_PAGE_IMPLEMENTED
        pmap_zero_part_page(m->phys_page, m_pa, len);
#else
        while (1) {
                tmp = vm_page_grab();
                if (tmp == VM_PAGE_NULL) {
                        vm_page_wait(THREAD_UNINT);
                        continue;
                }
                break;  
        }
        vm_page_zero_fill(tmp);
        if(m_pa != 0) {
                vm_page_part_copy(m, 0, tmp, 0, m_pa);
        }
        if((m_pa + len) <  PAGE_SIZE) {
                vm_page_part_copy(m, m_pa + len, tmp, 
                                m_pa + len, PAGE_SIZE - (m_pa + len));
        }
        vm_page_copy(tmp,m);
        vm_page_lock_queues();
        vm_page_free(tmp); 
        vm_page_unlock_queues();
#endif

}

/*
 *      vm_page_zero_fill:
 *
 *      Zero-fill the specified page.
 */
void
vm_page_zero_fill(
        vm_page_t       m)
{
        XPR(XPR_VM_PAGE,
                "vm_page_zero_fill, object 0x%X offset 0x%X page 0x%X\n",
                (integer_t)m->object, (integer_t)m->offset, (integer_t)m, 0,0);

        VM_PAGE_CHECK(m);

//      dbgTrace(0xAEAEAEAE, m->phys_page, 0);          /* (BRINGUP) */
        pmap_zero_page(m->phys_page);
}

/*
 *      vm_page_part_copy:
 *
 *      copy part of one page to another
 */

void
vm_page_part_copy(
        vm_page_t       src_m,
        vm_offset_t     src_pa,
        vm_page_t       dst_m,
        vm_offset_t     dst_pa,
        vm_size_t       len)
{
        VM_PAGE_CHECK(src_m);
        VM_PAGE_CHECK(dst_m);

        pmap_copy_part_page(src_m->phys_page, src_pa,
                        dst_m->phys_page, dst_pa, len);
}

/*
 *      vm_page_copy:
 *
 *      Copy one page to another
 *
 * ENCRYPTED SWAP:
 * The source page should not be encrypted.  The caller should
 * make sure the page is decrypted first, if necessary.
 */

int vm_page_copy_cs_validations = 0;
int vm_page_copy_cs_tainted = 0;

void
vm_page_copy(
        vm_page_t       src_m,
        vm_page_t       dest_m)
{
        XPR(XPR_VM_PAGE,
        "vm_page_copy, object 0x%X offset 0x%X to object 0x%X offset 0x%X\n",
        (integer_t)src_m->object, src_m->offset, 
        (integer_t)dest_m->object, dest_m->offset,
        0);

        VM_PAGE_CHECK(src_m);
        VM_PAGE_CHECK(dest_m);

        /*
         * ENCRYPTED SWAP:
         * The source page should not be encrypted at this point.
         * The destination page will therefore not contain encrypted
         * data after the copy.
         */
        if (src_m->encrypted) {
                panic("vm_page_copy: source page %p is encrypted\n", src_m);
        }
        dest_m->encrypted = FALSE;

        if (src_m->object != VM_OBJECT_NULL &&
            src_m->object->code_signed) {
                /*
                 * We're copying a page from a code-signed object.
                 * Whoever ends up mapping the copy page might care about
                 * the original page's integrity, so let's validate the
                 * source page now.
                 */
                vm_page_copy_cs_validations++;
                vm_page_validate_cs(src_m);
        }
        /*
         * Propagate the code-signing bits to the copy page.
         */
        dest_m->cs_validated = src_m->cs_validated;
        dest_m->cs_tainted = src_m->cs_tainted;
        if (dest_m->cs_tainted) {
                assert(dest_m->cs_validated);
                vm_page_copy_cs_tainted++;
        }

        pmap_copy_page(src_m->phys_page, dest_m->phys_page);
}

#if MACH_ASSERT
/*
 *      Check that the list of pages is ordered by
 *      ascending physical address and has no holes.
 */
static int
vm_page_verify_contiguous(
        vm_page_t       pages,
        unsigned int    npages)
{
        register vm_page_t      m;
        unsigned int            page_count;
        vm_offset_t             prev_addr;

        prev_addr = pages->phys_page;
        page_count = 1;
        for (m = NEXT_PAGE(pages); m != VM_PAGE_NULL; m = NEXT_PAGE(m)) {
                if (m->phys_page != prev_addr + 1) {
                        printf("m %p prev_addr 0x%x, current addr 0x%x\n",
                               m, prev_addr, m->phys_page);
                        printf("pages %p page_count %d\n", pages, page_count);
                        panic("vm_page_verify_contiguous:  not contiguous!");
                }
                prev_addr = m->phys_page;
                ++page_count;
        }
        if (page_count != npages) {
                printf("pages %p actual count 0x%x but requested 0x%x\n",
                       pages, page_count, npages);
                panic("vm_page_verify_contiguous:  count error");
        }
        return 1;
}
#endif  /* MACH_ASSERT */


#if MACH_ASSERT
/*
 *      Check the free lists for proper length etc.
 */
static void
vm_page_verify_free_lists( void )
{
        unsigned int    color, npages;
        vm_page_t       m;
        vm_page_t       prev_m;
        
        npages = 0;
        
        mutex_lock(&vm_page_queue_free_lock);

        for( color = 0; color < vm_colors; color++ ) {
                prev_m = (vm_page_t) &vm_page_queue_free[color];
                queue_iterate(&vm_page_queue_free[color],
                              m,
                              vm_page_t,
                              pageq) {
                        if ((vm_page_t) m->pageq.prev != prev_m)
                                panic("vm_page_verify_free_lists: corrupted prev ptr");
                        if ( ! m->free )
                                panic("vm_page_verify_free_lists: not free");
                        if ( ! m->busy )
                                panic("vm_page_verify_free_lists: not busy");
                        if ( (m->phys_page & vm_color_mask) != color)
                                panic("vm_page_verify_free_lists: wrong color");
                        ++npages;
                        prev_m = m;
                }
        }
        if (npages != vm_page_free_count)
                panic("vm_page_verify_free_lists:  npages %u free_count %d",
                      npages, vm_page_free_count);

        mutex_unlock(&vm_page_queue_free_lock);
}
#endif  /* MACH_ASSERT */



/*
 *      CONTIGUOUS PAGE ALLOCATION
 *      Additional levels of effort:
 *              + consider pages that are currently 'pmapped'
 *                  this could be expensive since we'd have
 *                  to ask the pmap layer about there state
 *              + consider dirty pages
 *                  either clean them or
 *                  copy them to other locations...
 *
 *      Find a region large enough to contain at least n pages
 *      of contiguous physical memory.
 *
 *      This is done by traversing the vm_page_t array in a linear fashion
 *      we assume that the vm_page_t array has the avaiable physical pages in an
 *      ordered, ascending list... this is currently true of all our implementations
 *      and must remain so... there can be 'holes' in the array...  we also can
 *      no longer tolerate the vm_page_t's in the list being 'freed' and reclaimed
 *      which use to happen via 'vm_page_convert'... that function was no longer
 *      being called and was removed...
 *      
 *      The basic flow consists of stabilizing some of the interesting state of 
 *      a vm_page_t behind the vm_page_queue and vm_page_free locks... we start our
 *      sweep at the beginning of the array looking for pages that meet our criterea
 *      for a 'stealable' page... currently we are pretty conservative... if the page
 *      meets this criterea and is physically contiguous to the previous page in the 'run'
 *      we keep developing it.  If we hit a page that doesn't fit, we reset our state
 *      and start to develop a new run... if at this point we've already considered
 *      at least MAX_CONSIDERED_BEFORE_YIELD pages, we'll drop the 2 locks we hold,
 *      and mutex_pause (which will yield the processor), to keep the latency low w/r 
 *      to other threads trying to acquire free pages (or move pages from q to q),
 *      and then continue from the spot we left off... we only make 1 pass through the
 *      array.  Once we have a 'run' that is long enough, we'll go into the loop which
 *      which steals the pages from the queues they're currently on... pages on the free
 *      queue can be stolen directly... pages that are on any of the other queues
 *      must be removed from the object they are tabled on... this requires taking the
 *      object lock... we do this as a 'try' to prevent deadlocks... if the 'try' fails
 *      or if the state of the page behind the vm_object lock is no longer viable, we'll
 *      dump the pages we've currently stolen back to the free list, and pick up our
 *      scan from the point where we aborted the 'current' run.
 *
 *
 *      Requirements:
 *              - neither vm_page_queue nor vm_free_list lock can be held on entry
 *
 *      Returns a pointer to a list of gobbled/wired pages or VM_PAGE_NULL.
 *
 * Algorithm:
 */

#define MAX_CONSIDERED_BEFORE_YIELD     1000


#define RESET_STATE_OF_RUN()    \
        MACRO_BEGIN             \
        prevcontaddr = -2;      \
        free_considered = 0;    \
        substitute_needed = 0;  \
        npages = 0;             \
        MACRO_END                       


static vm_page_t
vm_page_find_contiguous(
        unsigned int    contig_pages,
        ppnum_t         max_pnum,
        boolean_t       wire)
{
        vm_page_t       m = NULL;
        ppnum_t         prevcontaddr;
        unsigned int    npages, considered;
        unsigned int    page_idx, start_idx;
        int             free_considered, free_available;
        int             substitute_needed;
#if MACH_ASSERT
        uint32_t        tv_start_sec, tv_start_usec, tv_end_sec, tv_end_usec;
        int             yielded = 0;
        int             dumped_run = 0;
        int             stolen_pages = 0;
#endif

        if (contig_pages == 0)
                return VM_PAGE_NULL;

#if MACH_ASSERT
        vm_page_verify_free_lists();

        clock_get_system_microtime(&tv_start_sec, &tv_start_usec);
#endif
        vm_page_lock_queues();
        mutex_lock(&vm_page_queue_free_lock);

        RESET_STATE_OF_RUN();

        considered = 0;
        free_available = vm_page_free_count - vm_page_free_reserved;

        for (page_idx = 0, start_idx = 0;
             npages < contig_pages && page_idx < vm_pages_count;
             page_idx++) {
retry:          
                m = &vm_pages[page_idx];

                if (max_pnum && m->phys_page > max_pnum) {
                        /* no more low pages... */
                        break;
                }
                if (m->phys_page <= vm_lopage_poolend &&
                    m->phys_page >= vm_lopage_poolstart) {
                        /*
                         * don't want to take pages from our
                         * reserved pool of low memory
                         * so don't consider it which
                         * means starting a new run
                         */
                        RESET_STATE_OF_RUN();

                } else if (m->wire_count || m->gobbled ||
                           m->encrypted || m->encrypted_cleaning || m->cs_validated || m->cs_tainted ||
                           m->error || m->absent || m->pageout_queue || m->laundry || m->wanted || m->precious ||
                           m->cleaning || m->overwriting || m->restart || m->unusual || m->list_req_pending) {
                        /*
                         * page is in a transient state
                         * or a state we don't want to deal
                         * with, so don't consider it which
                         * means starting a new run
                         */
                        RESET_STATE_OF_RUN();

                } else if (!m->free && !m->active && !m->inactive && !m->speculative && !m->throttled) {
                        /*
                         * page needs to be on one of our queues
                         * in order for it to be stable behind the
                         * locks we hold at this point...
                         * if not, don't consider it which
                         * means starting a new run
                         */
                        RESET_STATE_OF_RUN();

                } else if (!m->free && (!m->tabled || m->busy)) {
                        /*
                         * pages on the free list are always 'busy'
                         * so we couldn't test for 'busy' in the check
                         * for the transient states... pages that are
                         * 'free' are never 'tabled', so we also couldn't
                         * test for 'tabled'.  So we check here to make
                         * sure that a non-free page is not busy and is
                         * tabled on an object... 
                         * if not, don't consider it which
                         * means starting a new run
                         */
                        RESET_STATE_OF_RUN();

                } else {
                        if (m->phys_page != prevcontaddr + 1) {
                                npages = 1;
                                start_idx = page_idx;
                        } else {
                                npages++;
                        }
                        prevcontaddr = m->phys_page;

                        if (m->pmapped || m->dirty)
                                substitute_needed++;

                        if (m->free) {
                                free_considered++;
                        }
                        if ((free_considered + substitute_needed) > free_available) {   
                                /*
                                 * if we let this run continue
                                 * we will end up dropping the vm_page_free_count
                                 * below the reserve limit... we need to abort
                                 * this run, but we can at least re-consider this
                                 * page... thus the jump back to 'retry'
                                 */
                                RESET_STATE_OF_RUN();

                                if (free_available && considered <= MAX_CONSIDERED_BEFORE_YIELD) {
                                        considered++;
                                        goto retry;
                                }
                                /*
                                 * free_available == 0
                                 * so can't consider any free pages... if
                                 * we went to retry in this case, we'd
                                 * get stuck looking at the same page
                                 * w/o making any forward progress
                                 * we also want to take this path if we've already
                                 * reached our limit that controls the lock latency
                                 */
                        }
                }
                if (considered > MAX_CONSIDERED_BEFORE_YIELD && npages <= 1) {
                        
                        mutex_unlock(&vm_page_queue_free_lock);
                        vm_page_unlock_queues();

                        mutex_pause(0);

                        vm_page_lock_queues();
                        mutex_lock(&vm_page_queue_free_lock);

                        RESET_STATE_OF_RUN();
                        /*
                         * reset our free page limit since we
                         * dropped the lock protecting the vm_page_free_queue
                         */
                        free_available = vm_page_free_count - vm_page_free_reserved;
                        considered = 0;
#if MACH_ASSERT
                        yielded++;
#endif
                        goto retry;
                }
                considered++;
        }
        m = VM_PAGE_NULL;

        if (npages != contig_pages)
                mutex_unlock(&vm_page_queue_free_lock);
        else {
                vm_page_t       m1;
                vm_page_t       m2;
                unsigned int    cur_idx;
                unsigned int    tmp_start_idx;
                vm_object_t     locked_object = VM_OBJECT_NULL;
                boolean_t       abort_run = FALSE;
                
                tmp_start_idx = start_idx;

                /*
                 * first pass through to pull the free pages
                 * off of the free queue so that in case we
                 * need substitute pages, we won't grab any 
                 * of the free pages in the run... we'll clear
                 * the 'free' bit in the 2nd pass, and even in
                 * an abort_run case, we'll collect all of the
                 * free pages in this run and return them to the free list
                 */
                while (start_idx < page_idx) {

                        m1 = &vm_pages[start_idx++];

                        if (m1->free) {
                                unsigned int color;

                                color = m1->phys_page & vm_color_mask;
                                queue_remove(&vm_page_queue_free[color],
                                             m1,
                                             vm_page_t,
                                             pageq);

                                vm_page_free_count--;
                        }
                }
                /*
                 * adjust global freelist counts
                 */
                if (vm_page_free_count < vm_page_free_count_minimum)
                        vm_page_free_count_minimum = vm_page_free_count;

                /*
                 * we can drop the free queue lock at this point since
                 * we've pulled any 'free' candidates off of the list
                 * we need it dropped so that we can do a vm_page_grab
                 * when substituing for pmapped/dirty pages
                 */
                mutex_unlock(&vm_page_queue_free_lock);

                start_idx = tmp_start_idx;
                cur_idx = page_idx - 1;

                while (start_idx++ < page_idx) {
                        /*
                         * must go through the list from back to front
                         * so that the page list is created in the
                         * correct order - low -> high phys addresses
                         */
                        m1 = &vm_pages[cur_idx--];

                        if (m1->free) {
                                /*
                                 * pages have already been removed from
                                 * the free list in the 1st pass
                                 */
                                assert(m1->free);
                                assert(m1->busy);
                                assert(!m1->wanted);
                                assert(!m1->laundry);
                                m1->free = FALSE;

                        } else {
                                vm_object_t object;

                                if (abort_run == TRUE)
                                        continue;

                                object = m1->object;

                                if (object != locked_object) {
                                        if (locked_object) {
                                                vm_object_unlock(locked_object);
                                                locked_object = VM_OBJECT_NULL;
                                        }
                                        if (vm_object_lock_try(object))
                                                locked_object = object;
                                }
                                if (locked_object == VM_OBJECT_NULL || 
                                    (m1->wire_count || m1->gobbled ||
                                     m1->encrypted || m1->encrypted_cleaning || m1->cs_validated || m1->cs_tainted ||
                                     m1->error || m1->absent || m1->pageout_queue || m1->laundry || m1->wanted || m1->precious ||
                                     m1->cleaning || m1->overwriting || m1->restart || m1->unusual || m1->list_req_pending || m1->busy)) {

                                        if (locked_object) {
                                                vm_object_unlock(locked_object);
                                                locked_object = VM_OBJECT_NULL;
                                        }
                                        tmp_start_idx = cur_idx;
                                        abort_run = TRUE;
                                        continue;
                                }
                                if (m1->pmapped || m1->dirty) {
                                        int refmod;
                                        vm_object_offset_t offset;

                                        m2 = vm_page_grab();

                                        if (m2 == VM_PAGE_NULL) {
                                                if (locked_object) {
                                                        vm_object_unlock(locked_object);
                                                        locked_object = VM_OBJECT_NULL;
                                                }
                                                tmp_start_idx = cur_idx;
                                                abort_run = TRUE;
                                                continue;
                                        }
                                        if (m1->pmapped)
                                                refmod = pmap_disconnect(m1->phys_page);
                                        else
                                                refmod = 0;
                                        vm_page_copy(m1, m2);
                  
                                        m2->reference = m1->reference;
                                        m2->dirty     = m1->dirty;

                                        if (refmod & VM_MEM_REFERENCED)
                                                m2->reference = TRUE;
                                        if (refmod & VM_MEM_MODIFIED)
                                                m2->dirty = TRUE;
                                        offset = m1->offset;

                                        /*
                                         * completely cleans up the state
                                         * of the page so that it is ready
                                         * to be put onto the free list, or
                                         * for this purpose it looks like it
                                         * just came off of the free list
                                         */
                                        vm_page_free_prepare(m1);

                                        /*
                                         * make sure we clear the ref/mod state
                                         * from the pmap layer... else we risk
                                         * inheriting state from the last time
                                         * this page was used...
                                         */
                                        pmap_clear_refmod(m2->phys_page, VM_MEM_MODIFIED | VM_MEM_REFERENCED);
                                        /*
                                         * now put the substitute page on the object
                                         */
                                        vm_page_insert_internal(m2, locked_object, offset, TRUE);

                                        if (m2->reference)
                                                vm_page_activate(m2);
                                        else
                                                vm_page_deactivate(m2);

                                        PAGE_WAKEUP_DONE(m2);

                                } else {
                                        /*
                                         * completely cleans up the state
                                         * of the page so that it is ready
                                         * to be put onto the free list, or
                                         * for this purpose it looks like it
                                         * just came off of the free list
                                         */
                                        vm_page_free_prepare(m1);
                                }
#if MACH_ASSERT
                                stolen_pages++;
#endif
                        }
                        m1->pageq.next = (queue_entry_t) m;
                        m1->pageq.prev = NULL;
                        m = m1;
                }
                if (locked_object) {
                        vm_object_unlock(locked_object);
                        locked_object = VM_OBJECT_NULL;
                }

                if (abort_run == TRUE) {
                        if (m != VM_PAGE_NULL) {
                                vm_page_free_list(m);
                        }
#if MACH_ASSERT
                        dumped_run++;
#endif
                        /*
                         * want the index of the last
                         * page in this run that was
                         * successfully 'stolen', so back
                         * it up 1 for the auto-decrement on use
                         * and 1 more to bump back over this page
                         */
                        page_idx = tmp_start_idx + 2;

                        if (page_idx >= vm_pages_count)
                                goto done_scanning;

                        mutex_lock(&vm_page_queue_free_lock);

                        RESET_STATE_OF_RUN();

                        /*
                         * reset our free page limit since we
                         * dropped the lock protecting the vm_page_free_queue
                         */
                        free_available = vm_page_free_count - vm_page_free_reserved;
                        
                        goto retry;
                }

                for (m1 = m; m1 != VM_PAGE_NULL; m1 = NEXT_PAGE(m1)) {

                        if (wire == TRUE)
                                m1->wire_count++;
                        else
                                m1->gobbled = TRUE;
                }
                if (wire == FALSE)
                        vm_page_gobble_count += npages;

                /*
                 * gobbled pages are also counted as wired pages
                 */
                vm_page_wire_count += npages;

                assert(vm_page_verify_contiguous(m, npages));
        }
done_scanning:
        vm_page_unlock_queues();

#if MACH_ASSERT
        clock_get_system_microtime(&tv_end_sec, &tv_end_usec);

        tv_end_sec -= tv_start_sec;
        if (tv_end_usec < tv_start_usec) {
                tv_end_sec--;
                tv_end_usec += 1000000;
        }
        tv_end_usec -= tv_start_usec;
        if (tv_end_usec >= 1000000) {
                tv_end_sec++;
                tv_end_sec -= 1000000;
        }
        printf("vm_find_page_contiguous(num=%d,low=%d): found %d pages in %d.%06ds...  scanned %d pages...  yielded %d times...  dumped run %d times... stole %d pages\n",
               contig_pages, max_pnum, npages, tv_end_sec, tv_end_usec, page_idx, yielded, dumped_run, stolen_pages);

        vm_page_verify_free_lists();
#endif
        return m;
}

/*
 *      Allocate a list of contiguous, wired pages.
 */
kern_return_t
cpm_allocate(
        vm_size_t       size,
        vm_page_t       *list,
        ppnum_t         max_pnum,
        boolean_t       wire)
{
        vm_page_t               pages;
        unsigned int            npages;

        if (size % page_size != 0)
                return KERN_INVALID_ARGUMENT;

        npages = size / page_size;

        /*
         *      Obtain a pointer to a subset of the free
         *      list large enough to satisfy the request;
         *      the region will be physically contiguous.
         */
        pages = vm_page_find_contiguous(npages, max_pnum, wire);

        if (pages == VM_PAGE_NULL)
                return KERN_NO_SPACE;
        /*
         * determine need for wakeups
         */
        if ((vm_page_free_count < vm_page_free_min) ||
            ((vm_page_free_count < vm_page_free_target) &&
             ((vm_page_inactive_count + vm_page_speculative_count) < vm_page_inactive_min)))
                thread_wakeup((event_t) &vm_page_free_wanted);
                
#if CONFIG_EMBEDDED
        {
        int                     percent_avail;

        /*
         * Decide if we need to poke the memorystatus notification thread.
         */
        percent_avail = 
                (vm_page_active_count + vm_page_inactive_count + 
                 vm_page_speculative_count + vm_page_free_count +
                 vm_page_purgeable_count ) * 100 /
                atop_64(max_mem);
        if (percent_avail <= (kern_memorystatus_level - 5)) {
                kern_memorystatus_level = percent_avail;
                thread_wakeup((event_t)&kern_memorystatus_wakeup);
        }
        }
#endif
        /*
         *      The CPM pages should now be available and
         *      ordered by ascending physical address.
         */
        assert(vm_page_verify_contiguous(pages, npages));

        *list = pages;
        return KERN_SUCCESS;
}
        

#include <mach_vm_debug.h>
#if     MACH_VM_DEBUG

#include <mach_debug/hash_info.h>
#include <vm/vm_debug.h>

/*
 *      Routine:        vm_page_info
 *      Purpose:
 *              Return information about the global VP table.
 *              Fills the buffer with as much information as possible
 *              and returns the desired size of the buffer.
 *      Conditions:
 *              Nothing locked.  The caller should provide
 *              possibly-pageable memory.
 */

unsigned int
vm_page_info(
        hash_info_bucket_t *info,
        unsigned int count)
{
        unsigned int i;

        if (vm_page_bucket_count < count)
                count = vm_page_bucket_count;

        for (i = 0; i < count; i++) {
                vm_page_bucket_t *bucket = &vm_page_buckets[i];
                unsigned int bucket_count = 0;
                vm_page_t m;

                simple_lock(&vm_page_bucket_lock);
                for (m = bucket->pages; m != VM_PAGE_NULL; m = m->next)
                        bucket_count++;
                simple_unlock(&vm_page_bucket_lock);

                /* don't touch pageable memory while holding locks */
                info[i].hib_count = bucket_count;
        }

        return vm_page_bucket_count;
}
#endif  /* MACH_VM_DEBUG */

#include <mach_kdb.h>
#if     MACH_KDB

#include <ddb/db_output.h>
#include <vm/vm_print.h>
#define printf  kdbprintf

/*
 *      Routine:        vm_page_print [exported]
 */
void
vm_page_print(
        db_addr_t       db_addr)
{
        vm_page_t       p;

        p = (vm_page_t) (long) db_addr;

        iprintf("page 0x%x\n", p);

        db_indent += 2;

        iprintf("object=0x%x", p->object);
        printf(", offset=0x%x", p->offset);
        printf(", wire_count=%d", p->wire_count);

        iprintf("%sinactive, %sactive, %sthrottled, %sgobbled, %slaundry, %sfree, %sref, %sencrypted\n",
                (p->inactive ? "" : "!"),
                (p->active ? "" : "!"),
                (p->throttled ? "" : "!"),
                (p->gobbled ? "" : "!"),
                (p->laundry ? "" : "!"),
                (p->free ? "" : "!"),
                (p->reference ? "" : "!"),
                (p->encrypted ? "" : "!"));
        iprintf("%sbusy, %swanted, %stabled, %sfictitious, %sprivate, %sprecious\n",
                (p->busy ? "" : "!"),
                (p->wanted ? "" : "!"),
                (p->tabled ? "" : "!"),
                (p->fictitious ? "" : "!"),
                (p->private ? "" : "!"),
                (p->precious ? "" : "!"));
        iprintf("%sabsent, %serror, %sdirty, %scleaning, %spageout, %sclustered\n",
                (p->absent ? "" : "!"),
                (p->error ? "" : "!"),
                (p->dirty ? "" : "!"),
                (p->cleaning ? "" : "!"),
                (p->pageout ? "" : "!"),
                (p->clustered ? "" : "!"));
        iprintf("%soverwriting, %srestart, %sunusual\n",
                (p->overwriting ? "" : "!"),
                (p->restart ? "" : "!"),
                (p->unusual ? "" : "!"));

        iprintf("phys_page=0x%x", p->phys_page);

        db_indent -= 2;
}
#endif  /* MACH_KDB */