[apple/xnu.git] / iokit / Kernel / IOMemoryDescriptor.cpp

/*
 * Copyright (c) 1998-2007 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
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1998 Apple Computer, Inc.  All rights reserved. 
 *
 * HISTORY
 *
 */


#include <sys/cdefs.h>

#include <IOKit/assert.h>
#include <IOKit/system.h>
#include <IOKit/IOLib.h>
#include <IOKit/IOMemoryDescriptor.h>
#include <IOKit/IOMapper.h>
#include <IOKit/IODMACommand.h>
#include <IOKit/IOKitKeysPrivate.h>

#ifndef __LP64__
#include <IOKit/IOSubMemoryDescriptor.h>
#endif /* !__LP64__ */

#include <IOKit/IOKitDebug.h>
#include <libkern/OSDebug.h>

#include "IOKitKernelInternal.h"

#include <libkern/c++/OSContainers.h>
#include <libkern/c++/OSDictionary.h>
#include <libkern/c++/OSArray.h>
#include <libkern/c++/OSSymbol.h>
#include <libkern/c++/OSNumber.h>

#include <sys/uio.h>

__BEGIN_DECLS
#include <vm/pmap.h>
#include <vm/vm_pageout.h>
#include <mach/memory_object_types.h>
#include <device/device_port.h>

#include <mach/vm_prot.h>
#include <mach/mach_vm.h>
#include <vm/vm_fault.h>
#include <vm/vm_protos.h>

extern ppnum_t pmap_find_phys(pmap_t pmap, addr64_t va);
extern void ipc_port_release_send(ipc_port_t port);

kern_return_t
memory_object_iopl_request(
        ipc_port_t              port,
        memory_object_offset_t  offset,
        vm_size_t               *upl_size,
        upl_t                   *upl_ptr,
        upl_page_info_array_t   user_page_list,
        unsigned int            *page_list_count,
        int                     *flags);

unsigned int  IOTranslateCacheBits(struct phys_entry *pp);

__END_DECLS

#define kIOMapperWaitSystem     ((IOMapper *) 1)

static IOMapper * gIOSystemMapper = NULL;

ppnum_t           gIOLastPage;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

OSDefineMetaClassAndAbstractStructors( IOMemoryDescriptor, OSObject )

#define super IOMemoryDescriptor

OSDefineMetaClassAndStructors(IOGeneralMemoryDescriptor, IOMemoryDescriptor)

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

static IORecursiveLock * gIOMemoryLock;

#define LOCK    IORecursiveLockLock( gIOMemoryLock)
#define UNLOCK  IORecursiveLockUnlock( gIOMemoryLock)
#define SLEEP   IORecursiveLockSleep( gIOMemoryLock, (void *)this, THREAD_UNINT)
#define WAKEUP  \
    IORecursiveLockWakeup( gIOMemoryLock, (void *)this, /* one-thread */ false)

#if 0
#define DEBG(fmt, args...)      { kprintf(fmt, ## args); }
#else
#define DEBG(fmt, args...)      {}
#endif

#define IOMD_DEBUG_DMAACTIVE    1

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

// Some data structures and accessor macros used by the initWithOptions
// Function

enum ioPLBlockFlags {
    kIOPLOnDevice  = 0x00000001,
    kIOPLExternUPL = 0x00000002,
};

struct typePersMDData
{
    const IOGeneralMemoryDescriptor *fMD;
    ipc_port_t fMemEntry;
};

struct ioPLBlock {
    upl_t fIOPL;
    vm_address_t fPageInfo;   // Pointer to page list or index into it
    uint32_t fIOMDOffset;           // The offset of this iopl in descriptor
    ppnum_t fMappedPage;            // Page number of first page in this iopl
    unsigned int fPageOffset;       // Offset within first page of iopl
    unsigned int fFlags;            // Flags
};

struct ioGMDData {
    IOMapper *  fMapper;
    uint8_t     fDMAMapNumAddressBits;
    uint64_t    fDMAMapAlignment;
    addr64_t    fMappedBase;
    uint64_t fPreparationID;
    unsigned int fPageCnt;
    unsigned char fDiscontig;
#if __LP64__
    // align arrays to 8 bytes so following macros work
    unsigned char fPad[3];
#endif
    upl_page_info_t fPageList[1]; /* variable length */
    ioPLBlock fBlocks[1]; /* variable length */
};

#define getDataP(osd)   ((ioGMDData *) (osd)->getBytesNoCopy())
#define getIOPLList(d)  ((ioPLBlock *) (void *)&(d->fPageList[d->fPageCnt]))
#define getNumIOPL(osd, d)      \
    (((osd)->getLength() - ((char *) getIOPLList(d) - (char *) d)) / sizeof(ioPLBlock))
#define getPageList(d)  (&(d->fPageList[0]))
#define computeDataSize(p, u) \
    (offsetof(ioGMDData, fPageList) + p * sizeof(upl_page_info_t) + u * sizeof(ioPLBlock))


/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#define next_page(a) ( trunc_page(a) + PAGE_SIZE )


extern "C" {

kern_return_t device_data_action(
               uintptr_t               device_handle, 
               ipc_port_t              device_pager,
               vm_prot_t               protection, 
               vm_object_offset_t      offset, 
               vm_size_t               size)
{
    kern_return_t        kr;
    IOMemoryDescriptorReserved * ref = (IOMemoryDescriptorReserved *) device_handle;
    IOMemoryDescriptor * memDesc;

    LOCK;
    memDesc = ref->dp.memory;
    if( memDesc)
    {
        memDesc->retain();
        kr = memDesc->handleFault( device_pager, 0, 0,
                offset, size, kIOMapDefaultCache /*?*/);
        memDesc->release();
    }
    else
        kr = KERN_ABORTED;
    UNLOCK;

    return( kr );
}

kern_return_t device_close(
               uintptr_t     device_handle)
{
    IOMemoryDescriptorReserved * ref = (IOMemoryDescriptorReserved *) device_handle;

    IODelete( ref, IOMemoryDescriptorReserved, 1 );

    return( kIOReturnSuccess );
}
};      // end extern "C"

// Note this inline function uses C++ reference arguments to return values
// This means that pointers are not passed and NULLs don't have to be
// checked for as a NULL reference is illegal.
static inline void
getAddrLenForInd(user_addr_t &addr, IOPhysicalLength &len, // Output variables
     UInt32 type, IOGeneralMemoryDescriptor::Ranges r, UInt32 ind)
{
    assert(kIOMemoryTypeUIO       == type
        || kIOMemoryTypeVirtual   == type || kIOMemoryTypeVirtual64 == type
        || kIOMemoryTypePhysical  == type || kIOMemoryTypePhysical64 == type);
    if (kIOMemoryTypeUIO == type) {
        user_size_t us;
        uio_getiov((uio_t) r.uio, ind, &addr, &us); len = us;
    }
#ifndef __LP64__
    else if ((kIOMemoryTypeVirtual64 == type) || (kIOMemoryTypePhysical64 == type)) {
        IOAddressRange cur = r.v64[ind];
        addr = cur.address;
        len  = cur.length;
    }
#endif /* !__LP64__ */
    else {
        IOVirtualRange cur = r.v[ind];
        addr = cur.address;
        len  = cur.length;
    }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

IOMemoryDescriptor *
IOMemoryDescriptor::withAddress(void *      address,
                                IOByteCount   length,
                                IODirection direction)
{
    return IOMemoryDescriptor::
        withAddressRange((IOVirtualAddress) address, length, direction | kIOMemoryAutoPrepare, kernel_task);
}

#ifndef __LP64__
IOMemoryDescriptor *
IOMemoryDescriptor::withAddress(IOVirtualAddress address,
                                IOByteCount  length,
                                IODirection  direction,
                                task_t       task)
{
    IOGeneralMemoryDescriptor * that = new IOGeneralMemoryDescriptor;
    if (that)
    {
        if (that->initWithAddress(address, length, direction, task))
            return that;

        that->release();
    }
    return 0;
}
#endif /* !__LP64__ */

IOMemoryDescriptor *
IOMemoryDescriptor::withPhysicalAddress(
                                IOPhysicalAddress       address,
                                IOByteCount             length,
                                IODirection             direction )
{
    return (IOMemoryDescriptor::withAddressRange(address, length, direction, TASK_NULL));
}

#ifndef __LP64__
IOMemoryDescriptor *
IOMemoryDescriptor::withRanges( IOVirtualRange * ranges,
                                UInt32           withCount,
                                IODirection      direction,
                                task_t           task,
                                bool             asReference)
{
    IOGeneralMemoryDescriptor * that = new IOGeneralMemoryDescriptor;
    if (that)
    {
        if (that->initWithRanges(ranges, withCount, direction, task, asReference))
            return that;

        that->release();
    }
    return 0;
}
#endif /* !__LP64__ */

IOMemoryDescriptor *
IOMemoryDescriptor::withAddressRange(mach_vm_address_t address,
                                        mach_vm_size_t length,
                                        IOOptionBits   options,
                                        task_t         task)
{
    IOAddressRange range = { address, length };
    return (IOMemoryDescriptor::withAddressRanges(&range, 1, options, task));
}

IOMemoryDescriptor *
IOMemoryDescriptor::withAddressRanges(IOAddressRange *   ranges,
                                        UInt32           rangeCount,
                                        IOOptionBits     options,
                                        task_t           task)
{
    IOGeneralMemoryDescriptor * that = new IOGeneralMemoryDescriptor;
    if (that)
    {
        if (task)
            options |= kIOMemoryTypeVirtual64;
        else
            options |= kIOMemoryTypePhysical64;

        if (that->initWithOptions(ranges, rangeCount, 0, task, options, /* mapper */ 0))
            return that;

        that->release();
    }

    return 0;
}


/*
 * withOptions:
 *
 * Create a new IOMemoryDescriptor. The buffer is made up of several
 * virtual address ranges, from a given task.
 *
 * Passing the ranges as a reference will avoid an extra allocation.
 */
IOMemoryDescriptor *
IOMemoryDescriptor::withOptions(void *          buffers,
                                UInt32          count,
                                UInt32          offset,
                                task_t          task,
                                IOOptionBits    opts,
                                IOMapper *      mapper)
{
    IOGeneralMemoryDescriptor *self = new IOGeneralMemoryDescriptor;

    if (self
    && !self->initWithOptions(buffers, count, offset, task, opts, mapper))
    {
        self->release();
        return 0;
    }

    return self;
}

bool IOMemoryDescriptor::initWithOptions(void *         buffers,
                                         UInt32         count,
                                         UInt32         offset,
                                         task_t         task,
                                         IOOptionBits   options,
                                         IOMapper *     mapper)
{
    return( false );
}

#ifndef __LP64__
IOMemoryDescriptor *
IOMemoryDescriptor::withPhysicalRanges( IOPhysicalRange * ranges,
                                        UInt32          withCount,
                                        IODirection     direction,
                                        bool            asReference)
{
    IOGeneralMemoryDescriptor * that = new IOGeneralMemoryDescriptor;
    if (that)
    {
        if (that->initWithPhysicalRanges(ranges, withCount, direction, asReference))
            return that;

        that->release();
    }
    return 0;
}

IOMemoryDescriptor *
IOMemoryDescriptor::withSubRange(IOMemoryDescriptor *   of,
                                IOByteCount             offset,
                                IOByteCount             length,
                                IODirection             direction)
{
    return (IOSubMemoryDescriptor::withSubRange(of, offset, length, direction | kIOMemoryThreadSafe));
}
#endif /* !__LP64__ */

IOMemoryDescriptor *
IOMemoryDescriptor::withPersistentMemoryDescriptor(IOMemoryDescriptor *originalMD)
{
    IOGeneralMemoryDescriptor *origGenMD = 
        OSDynamicCast(IOGeneralMemoryDescriptor, originalMD);

    if (origGenMD)
        return IOGeneralMemoryDescriptor::
            withPersistentMemoryDescriptor(origGenMD);
    else
        return 0;
}

IOMemoryDescriptor *
IOGeneralMemoryDescriptor::withPersistentMemoryDescriptor(IOGeneralMemoryDescriptor *originalMD)
{
    ipc_port_t sharedMem = (ipc_port_t) originalMD->createNamedEntry();

    if (!sharedMem)
        return 0;
   
    if (sharedMem == originalMD->_memEntry) {
        originalMD->retain();               // Add a new reference to ourselves
        ipc_port_release_send(sharedMem);   // Remove extra send right
        return originalMD;
    }

    IOGeneralMemoryDescriptor * self = new IOGeneralMemoryDescriptor;
    typePersMDData initData = { originalMD, sharedMem };

    if (self
    && !self->initWithOptions(&initData, 1, 0, 0, kIOMemoryTypePersistentMD, 0)) {
        self->release();
        self = 0;
    }
    return self;
}

void *IOGeneralMemoryDescriptor::createNamedEntry()
{
    kern_return_t error;
    ipc_port_t sharedMem;

    IOOptionBits type = _flags & kIOMemoryTypeMask;

    user_addr_t range0Addr;
    IOByteCount range0Len;
    getAddrLenForInd(range0Addr, range0Len, type, _ranges, 0);
    range0Addr = trunc_page_64(range0Addr);

    vm_size_t size = ptoa_32(_pages);
    vm_address_t kernelPage = (vm_address_t) range0Addr;

    vm_map_t theMap = ((_task == kernel_task)
                        && (kIOMemoryBufferPageable & _flags)) 
                    ? IOPageableMapForAddress(kernelPage)
                    : get_task_map(_task);

    memory_object_size_t  actualSize = size;
    vm_prot_t             prot       = VM_PROT_READ;
    if (kIODirectionOut != (kIODirectionOutIn & _flags))
        prot |= VM_PROT_WRITE;

    if (_memEntry)
        prot |= MAP_MEM_NAMED_REUSE;

    error = mach_make_memory_entry_64(theMap,
            &actualSize, range0Addr, prot, &sharedMem, (ipc_port_t) _memEntry);

    if (KERN_SUCCESS == error) {
        if (actualSize == size) {
            return sharedMem;
        } else {
#if IOASSERT
            IOLog("IOGMD::mach_make_memory_entry_64 (%08llx) size (%08llx:%08llx)\n",
                  (UInt64)range0Addr, (UInt64)actualSize, (UInt64)size);
#endif    
            ipc_port_release_send( sharedMem );
        }
    }

    return MACH_PORT_NULL;
}

#ifndef __LP64__
bool
IOGeneralMemoryDescriptor::initWithAddress(void *      address,
                                    IOByteCount   withLength,
                                    IODirection withDirection)
{
    _singleRange.v.address = (vm_offset_t) address;
    _singleRange.v.length  = withLength;

    return initWithRanges(&_singleRange.v, 1, withDirection, kernel_task, true);
}

bool
IOGeneralMemoryDescriptor::initWithAddress(IOVirtualAddress address,
                                    IOByteCount    withLength,
                                    IODirection  withDirection,
                                    task_t       withTask)
{
    _singleRange.v.address = address;
    _singleRange.v.length  = withLength;

    return initWithRanges(&_singleRange.v, 1, withDirection, withTask, true);
}

bool
IOGeneralMemoryDescriptor::initWithPhysicalAddress(
                                 IOPhysicalAddress      address,
                                 IOByteCount            withLength,
                                 IODirection            withDirection )
{
    _singleRange.p.address = address;
    _singleRange.p.length  = withLength;

    return initWithPhysicalRanges( &_singleRange.p, 1, withDirection, true);
}

bool
IOGeneralMemoryDescriptor::initWithPhysicalRanges(
                                IOPhysicalRange * ranges,
                                UInt32            count,
                                IODirection       direction,
                                bool              reference)
{
    IOOptionBits mdOpts = direction | kIOMemoryTypePhysical;

    if (reference)
        mdOpts |= kIOMemoryAsReference;

    return initWithOptions(ranges, count, 0, 0, mdOpts, /* mapper */ 0);
}

bool
IOGeneralMemoryDescriptor::initWithRanges(
                                   IOVirtualRange * ranges,
                                   UInt32           count,
                                   IODirection      direction,
                                   task_t           task,
                                   bool             reference)
{
    IOOptionBits mdOpts = direction;

    if (reference)
        mdOpts |= kIOMemoryAsReference;

    if (task) {
        mdOpts |= kIOMemoryTypeVirtual;

        // Auto-prepare if this is a kernel memory descriptor as very few
        // clients bother to prepare() kernel memory.
        // But it was not enforced so what are you going to do?
        if (task == kernel_task)
            mdOpts |= kIOMemoryAutoPrepare;
    }
    else
        mdOpts |= kIOMemoryTypePhysical;
    
    return initWithOptions(ranges, count, 0, task, mdOpts, /* mapper */ 0);
}
#endif /* !__LP64__ */

/*
 * initWithOptions:
 *
 *  IOMemoryDescriptor. The buffer is made up of several virtual address ranges,
 * from a given task, several physical ranges, an UPL from the ubc
 * system or a uio (may be 64bit) from the BSD subsystem.
 *
 * Passing the ranges as a reference will avoid an extra allocation.
 *
 * An IOMemoryDescriptor can be re-used by calling initWithOptions again on an
 * existing instance -- note this behavior is not commonly supported in other
 * I/O Kit classes, although it is supported here.
 */

bool
IOGeneralMemoryDescriptor::initWithOptions(void *       buffers,
                                           UInt32       count,
                                           UInt32       offset,
                                           task_t       task,
                                           IOOptionBits options,
                                           IOMapper *   mapper)
{
    IOOptionBits type = options & kIOMemoryTypeMask;

#ifndef __LP64__
    if (task
        && (kIOMemoryTypeVirtual == type)
        && vm_map_is_64bit(get_task_map(task)) 
        && ((IOVirtualRange *) buffers)->address)
    {
        OSReportWithBacktrace("IOMemoryDescriptor: attempt to create 32b virtual in 64b task, use ::withAddressRange()");
        return false;
    }
#endif /* !__LP64__ */

    // Grab the original MD's configuation data to initialse the
    // arguments to this function.
    if (kIOMemoryTypePersistentMD == type) {

        typePersMDData *initData = (typePersMDData *) buffers;
        const IOGeneralMemoryDescriptor *orig = initData->fMD;
        ioGMDData *dataP = getDataP(orig->_memoryEntries);

        // Only accept persistent memory descriptors with valid dataP data.
        assert(orig->_rangesCount == 1);
        if ( !(orig->_flags & kIOMemoryPersistent) || !dataP)
            return false;

        _memEntry = initData->fMemEntry;        // Grab the new named entry
        options = orig->_flags & ~kIOMemoryAsReference; 
        type = options & kIOMemoryTypeMask;
        buffers = orig->_ranges.v;
        count = orig->_rangesCount;

        // Now grab the original task and whatever mapper was previously used
        task = orig->_task;
        mapper = dataP->fMapper;

        // We are ready to go through the original initialisation now
    }

    switch (type) {
    case kIOMemoryTypeUIO:
    case kIOMemoryTypeVirtual:
#ifndef __LP64__
    case kIOMemoryTypeVirtual64:
#endif /* !__LP64__ */
        assert(task);
        if (!task)
            return false;
        break;

    case kIOMemoryTypePhysical:         // Neither Physical nor UPL should have a task
#ifndef __LP64__
    case kIOMemoryTypePhysical64:
#endif /* !__LP64__ */
    case kIOMemoryTypeUPL:
        assert(!task);
        break;
    default:
        return false;   /* bad argument */
    }

    assert(buffers);
    assert(count);

    /*
     * We can check the _initialized  instance variable before having ever set
     * it to an initial value because I/O Kit guarantees that all our instance
     * variables are zeroed on an object's allocation.
     */

    if (_initialized) {
        /*
         * An existing memory descriptor is being retargeted to point to
         * somewhere else.  Clean up our present state.
         */
        IOOptionBits type = _flags & kIOMemoryTypeMask;
        if ((kIOMemoryTypePhysical != type) && (kIOMemoryTypePhysical64 != type))
        {
            while (_wireCount)
                complete();
        }
        if (_ranges.v && !(kIOMemoryAsReference & _flags))
        {
            if (kIOMemoryTypeUIO == type)
                uio_free((uio_t) _ranges.v);
#ifndef __LP64__
            else if ((kIOMemoryTypeVirtual64 == type) || (kIOMemoryTypePhysical64 == type))
                IODelete(_ranges.v64, IOAddressRange, _rangesCount);
#endif /* !__LP64__ */
            else
                IODelete(_ranges.v, IOVirtualRange, _rangesCount);
        }

        options |= (kIOMemoryRedirected & _flags);
        if (!(kIOMemoryRedirected & options))
        {
            if (_memEntry)
            {
                ipc_port_release_send((ipc_port_t) _memEntry);
                _memEntry = 0;
            }
            if (_mappings)
                _mappings->flushCollection();
        }
    }
    else {
        if (!super::init())
            return false;
        _initialized = true;
    }

    // Grab the appropriate mapper
    if (kIOMemoryHostOnly & options) options |= kIOMemoryMapperNone;
    if (kIOMemoryMapperNone & options)
        mapper = 0;     // No Mapper
    else if (mapper == kIOMapperSystem) {
        IOMapper::checkForSystemMapper();
        gIOSystemMapper = mapper = IOMapper::gSystem;
    }

    // Temp binary compatibility for kIOMemoryThreadSafe
    if (kIOMemoryReserved6156215 & options)
    {
        options &= ~kIOMemoryReserved6156215;
        options |= kIOMemoryThreadSafe;
    }
    // Remove the dynamic internal use flags from the initial setting
    options               &= ~(kIOMemoryPreparedReadOnly);
    _flags                 = options;
    _task                  = task;

#ifndef __LP64__
    _direction             = (IODirection) (_flags & kIOMemoryDirectionMask);
#endif /* !__LP64__ */

    __iomd_reservedA = 0;
    __iomd_reservedB = 0;
    _highestPage = 0;

    if (kIOMemoryThreadSafe & options)
    {
        if (!_prepareLock)
            _prepareLock = IOLockAlloc();
    }
    else if (_prepareLock)
    {
        IOLockFree(_prepareLock);
        _prepareLock = NULL;
    }
        
    if (kIOMemoryTypeUPL == type) {

        ioGMDData *dataP;
        unsigned int dataSize = computeDataSize(/* pages */ 0, /* upls */ 1);

        if (!initMemoryEntries(dataSize, mapper)) return (false);
        dataP = getDataP(_memoryEntries);
        dataP->fPageCnt = 0;

 //       _wireCount++; // UPLs start out life wired

        _length    = count;
        _pages    += atop_32(offset + count + PAGE_MASK) - atop_32(offset);

        ioPLBlock iopl;
        iopl.fIOPL = (upl_t) buffers;
        upl_set_referenced(iopl.fIOPL, true);
        upl_page_info_t *pageList = UPL_GET_INTERNAL_PAGE_LIST(iopl.fIOPL);

        if (upl_get_size(iopl.fIOPL) < (count + offset))
            panic("short external upl");

        _highestPage = upl_get_highest_page(iopl.fIOPL);

        // Set the flag kIOPLOnDevice convieniently equal to 1
        iopl.fFlags  = pageList->device | kIOPLExternUPL;
        if (!pageList->device) {
            // Pre-compute the offset into the UPL's page list
            pageList = &pageList[atop_32(offset)];
            offset &= PAGE_MASK;
        }
        iopl.fIOMDOffset = 0;
        iopl.fMappedPage = 0;
        iopl.fPageInfo = (vm_address_t) pageList;
        iopl.fPageOffset = offset;
        _memoryEntries->appendBytes(&iopl, sizeof(iopl));
    }
    else {
        // kIOMemoryTypeVirtual  | kIOMemoryTypeVirtual64 | kIOMemoryTypeUIO 
        // kIOMemoryTypePhysical | kIOMemoryTypePhysical64
        
        // Initialize the memory descriptor
        if (options & kIOMemoryAsReference) {
#ifndef __LP64__
            _rangesIsAllocated = false;
#endif /* !__LP64__ */

            // Hack assignment to get the buffer arg into _ranges.
            // I'd prefer to do _ranges = (Ranges) buffers, but that doesn't
            // work, C++ sigh.
            // This also initialises the uio & physical ranges.
            _ranges.v = (IOVirtualRange *) buffers;
        }
        else {
#ifndef __LP64__
            _rangesIsAllocated = true;
#endif /* !__LP64__ */
            switch (type)
            {
              case kIOMemoryTypeUIO:
                _ranges.v = (IOVirtualRange *) uio_duplicate((uio_t) buffers);
                break;

#ifndef __LP64__
              case kIOMemoryTypeVirtual64:
              case kIOMemoryTypePhysical64:
                if (count == 1
                    && (((IOAddressRange *) buffers)->address + ((IOAddressRange *) buffers)->length) <= 0x100000000ULL
                    ) {
                    if (kIOMemoryTypeVirtual64 == type)
                        type = kIOMemoryTypeVirtual;
                    else
                        type = kIOMemoryTypePhysical;
                    _flags = (_flags & ~kIOMemoryTypeMask) | type | kIOMemoryAsReference;
                    _rangesIsAllocated = false;
                    _ranges.v = &_singleRange.v;
                    _singleRange.v.address = ((IOAddressRange *) buffers)->address;
                    _singleRange.v.length  = ((IOAddressRange *) buffers)->length;
                    break;
                }
                _ranges.v64 = IONew(IOAddressRange, count);
                if (!_ranges.v64)
                    return false;
                bcopy(buffers, _ranges.v, count * sizeof(IOAddressRange));
                break;
#endif /* !__LP64__ */
              case kIOMemoryTypeVirtual:
              case kIOMemoryTypePhysical:
                if (count == 1) {
                    _flags |= kIOMemoryAsReference;
#ifndef __LP64__
                    _rangesIsAllocated = false;
#endif /* !__LP64__ */
                    _ranges.v = &_singleRange.v;
                } else {
                    _ranges.v = IONew(IOVirtualRange, count);
                    if (!_ranges.v)
                        return false;
                }
                bcopy(buffers, _ranges.v, count * sizeof(IOVirtualRange));
                break;
            }
        } 

        // Find starting address within the vector of ranges
        Ranges vec = _ranges;
        UInt32 length = 0;
        UInt32 pages = 0;
        for (unsigned ind = 0; ind < count;  ind++) {
            user_addr_t addr;
            IOPhysicalLength len;

            // addr & len are returned by this function
            getAddrLenForInd(addr, len, type, vec, ind);
            pages += (atop_64(addr + len + PAGE_MASK) - atop_64(addr));
            len += length;
            assert(len >= length);      // Check for 32 bit wrap around
            length = len;

            if ((kIOMemoryTypePhysical == type) || (kIOMemoryTypePhysical64 == type))
            {
                ppnum_t highPage = atop_64(addr + len - 1);
                if (highPage > _highestPage)
                    _highestPage = highPage;
            }
        } 
        _length      = length;
        _pages       = pages;
        _rangesCount = count;

        // Auto-prepare memory at creation time.
        // Implied completion when descriptor is free-ed
        if ((kIOMemoryTypePhysical == type) || (kIOMemoryTypePhysical64 == type))
            _wireCount++;       // Physical MDs are, by definition, wired
        else { /* kIOMemoryTypeVirtual | kIOMemoryTypeVirtual64 | kIOMemoryTypeUIO */
            ioGMDData *dataP;
            unsigned dataSize = computeDataSize(_pages, /* upls */ count * 2);

            if (!initMemoryEntries(dataSize, mapper)) return false;
            dataP = getDataP(_memoryEntries);
            dataP->fPageCnt = _pages;

            if ( (kIOMemoryPersistent & _flags) && !_memEntry)
                _memEntry = createNamedEntry();

            if ((_flags & kIOMemoryAutoPrepare)
             && prepare() != kIOReturnSuccess)
                return false;
        }
    }

    return true;
}

/*
 * free
 *
 * Free resources.
 */
void IOGeneralMemoryDescriptor::free()
{
    IOOptionBits type = _flags & kIOMemoryTypeMask;

    if( reserved)
    {
        LOCK;
        reserved->dp.memory = 0;
        UNLOCK;
    }
    if ((kIOMemoryTypePhysical == type) || (kIOMemoryTypePhysical64 == type))
    {
        ioGMDData * dataP;
        if (_memoryEntries && (dataP = getDataP(_memoryEntries)) && dataP->fMappedBase)
        {
            dataP->fMapper->iovmFree(atop_64(dataP->fMappedBase), _pages);
            dataP->fMappedBase = 0;
        }
    }
    else
    {
        while (_wireCount) complete();
    }

    if (_memoryEntries) _memoryEntries->release();

    if (_ranges.v && !(kIOMemoryAsReference & _flags))
    {
        if (kIOMemoryTypeUIO == type)
            uio_free((uio_t) _ranges.v);
#ifndef __LP64__
        else if ((kIOMemoryTypeVirtual64 == type) || (kIOMemoryTypePhysical64 == type))
            IODelete(_ranges.v64, IOAddressRange, _rangesCount);
#endif /* !__LP64__ */
        else
            IODelete(_ranges.v, IOVirtualRange, _rangesCount);

        _ranges.v = NULL;
    }

    if (reserved)
    {
        if (reserved->dp.devicePager)
        {
            // memEntry holds a ref on the device pager which owns reserved
            // (IOMemoryDescriptorReserved) so no reserved access after this point
            device_pager_deallocate( (memory_object_t) reserved->dp.devicePager );
        }
        else
            IODelete(reserved, IOMemoryDescriptorReserved, 1);
        reserved = NULL;
    }

    if (_memEntry)
        ipc_port_release_send( (ipc_port_t) _memEntry );

    if (_prepareLock)
        IOLockFree(_prepareLock);

    super::free();
}

#ifndef __LP64__
void IOGeneralMemoryDescriptor::unmapFromKernel()
{
    panic("IOGMD::unmapFromKernel deprecated");
}

void IOGeneralMemoryDescriptor::mapIntoKernel(unsigned rangeIndex)
{
    panic("IOGMD::mapIntoKernel deprecated");
}
#endif /* !__LP64__ */

/*
 * getDirection:
 *
 * Get the direction of the transfer.
 */
IODirection IOMemoryDescriptor::getDirection() const
{
#ifndef __LP64__
    if (_direction)
        return _direction;
#endif /* !__LP64__ */
    return (IODirection) (_flags & kIOMemoryDirectionMask);
}

/*
 * getLength:
 *
 * Get the length of the transfer (over all ranges).
 */
IOByteCount IOMemoryDescriptor::getLength() const
{
    return _length;
}

void IOMemoryDescriptor::setTag( IOOptionBits tag )
{
    _tag = tag;    
}

IOOptionBits IOMemoryDescriptor::getTag( void )
{
    return( _tag);
}

#ifndef __LP64__
// @@@ gvdl: who is using this API?  Seems like a wierd thing to implement.
IOPhysicalAddress
IOMemoryDescriptor::getSourceSegment( IOByteCount   offset, IOByteCount * length )
{
    addr64_t physAddr = 0;

    if( prepare() == kIOReturnSuccess) {
        physAddr = getPhysicalSegment64( offset, length );
        complete();
    }

    return( (IOPhysicalAddress) physAddr ); // truncated but only page offset is used
}
#endif /* !__LP64__ */

IOByteCount IOMemoryDescriptor::readBytes
                (IOByteCount offset, void *bytes, IOByteCount length)
{
    addr64_t dstAddr = CAST_DOWN(addr64_t, bytes);
    IOByteCount remaining;

    // Assert that this entire I/O is withing the available range
    assert(offset < _length);
    assert(offset + length <= _length);
    if (offset >= _length) {
        return 0;
    }

    if (kIOMemoryThreadSafe & _flags)
        LOCK;

    remaining = length = min(length, _length - offset);
    while (remaining) { // (process another target segment?)
        addr64_t        srcAddr64;
        IOByteCount     srcLen;

        srcAddr64 = getPhysicalSegment(offset, &srcLen, kIOMemoryMapperNone);
        if (!srcAddr64)
            break;

        // Clip segment length to remaining
        if (srcLen > remaining)
            srcLen = remaining;

        copypv(srcAddr64, dstAddr, srcLen,
                            cppvPsrc | cppvNoRefSrc | cppvFsnk | cppvKmap);

        dstAddr   += srcLen;
        offset    += srcLen;
        remaining -= srcLen;
    }

    if (kIOMemoryThreadSafe & _flags)
        UNLOCK;

    assert(!remaining);

    return length - remaining;
}

IOByteCount IOMemoryDescriptor::writeBytes
                (IOByteCount offset, const void *bytes, IOByteCount length)
{
    addr64_t srcAddr = CAST_DOWN(addr64_t, bytes);
    IOByteCount remaining;

    // Assert that this entire I/O is withing the available range
    assert(offset < _length);
    assert(offset + length <= _length);

    assert( !(kIOMemoryPreparedReadOnly & _flags) );

    if ( (kIOMemoryPreparedReadOnly & _flags) || offset >= _length) {
        return 0;
    }

    if (kIOMemoryThreadSafe & _flags)
        LOCK;

    remaining = length = min(length, _length - offset);
    while (remaining) { // (process another target segment?)
        addr64_t    dstAddr64;
        IOByteCount dstLen;

        dstAddr64 = getPhysicalSegment(offset, &dstLen, kIOMemoryMapperNone);
        if (!dstAddr64)
            break;

        // Clip segment length to remaining
        if (dstLen > remaining)
            dstLen = remaining;

        copypv(srcAddr, (addr64_t) dstAddr64, dstLen,
                            cppvPsnk | cppvFsnk | cppvNoRefSrc | cppvNoModSnk | cppvKmap);

        srcAddr   += dstLen;
        offset    += dstLen;
        remaining -= dstLen;
    }

    if (kIOMemoryThreadSafe & _flags)
        UNLOCK;

    assert(!remaining);

    return length - remaining;
}

// osfmk/device/iokit_rpc.c
extern "C" unsigned int IODefaultCacheBits(addr64_t pa);

#ifndef __LP64__
void IOGeneralMemoryDescriptor::setPosition(IOByteCount position)
{
    panic("IOGMD::setPosition deprecated");
}
#endif /* !__LP64__ */

static volatile SInt64 gIOMDPreparationID __attribute__((aligned(8))) = (1ULL << 32);

uint64_t
IOGeneralMemoryDescriptor::getPreparationID( void )
{
    ioGMDData *dataP;

    if (!_wireCount)
        return (kIOPreparationIDUnprepared);

    if (((kIOMemoryTypeMask & _flags) == kIOMemoryTypePhysical)
      || ((kIOMemoryTypeMask & _flags) == kIOMemoryTypePhysical64))
    {
        IOMemoryDescriptor::setPreparationID();
        return (IOMemoryDescriptor::getPreparationID());
    }

    if (!_memoryEntries || !(dataP = getDataP(_memoryEntries)))
        return (kIOPreparationIDUnprepared);

    if (kIOPreparationIDUnprepared == dataP->fPreparationID)
    {
        dataP->fPreparationID = OSIncrementAtomic64(&gIOMDPreparationID);
    }
    return (dataP->fPreparationID);
}

IOMemoryDescriptorReserved * IOMemoryDescriptor::getKernelReserved( void )
{
    if (!reserved)
    {
        reserved = IONew(IOMemoryDescriptorReserved, 1);
        if (reserved)
            bzero(reserved, sizeof(IOMemoryDescriptorReserved));
    }
    return (reserved);
}

void IOMemoryDescriptor::setPreparationID( void )
{
    if (getKernelReserved() && (kIOPreparationIDUnprepared == reserved->preparationID))
    {
#if defined(__ppc__ )
        reserved->preparationID = gIOMDPreparationID++;
#else
        reserved->preparationID = OSIncrementAtomic64(&gIOMDPreparationID);
#endif
    }
}

uint64_t IOMemoryDescriptor::getPreparationID( void )
{
    if (reserved)
        return (reserved->preparationID);    
    else
        return (kIOPreparationIDUnsupported);    
}

IOReturn IOGeneralMemoryDescriptor::dmaCommandOperation(DMACommandOps op, void *vData, UInt dataSize) const
{
    IOReturn err = kIOReturnSuccess;
    DMACommandOps params;
    IOGeneralMemoryDescriptor * md = const_cast<IOGeneralMemoryDescriptor *>(this);
    ioGMDData *dataP;

    params = (op & ~kIOMDDMACommandOperationMask & op);
    op &= kIOMDDMACommandOperationMask;

    if (kIOMDDMAMap == op)
    {
        if (dataSize < sizeof(IOMDDMAMapArgs))
            return kIOReturnUnderrun;

        IOMDDMAMapArgs * data = (IOMDDMAMapArgs *) vData;

        if (!_memoryEntries 
            && !md->initMemoryEntries(computeDataSize(0, 0), kIOMapperWaitSystem)) return (kIOReturnNoMemory);

        if (_memoryEntries && data->fMapper)
        {
            bool remap;
            bool whole = ((data->fOffset == 0) && (data->fLength == _length));
            dataP = getDataP(_memoryEntries);

            if (data->fMapSpec.numAddressBits < dataP->fDMAMapNumAddressBits) dataP->fDMAMapNumAddressBits = data->fMapSpec.numAddressBits;
            if (data->fMapSpec.alignment      > dataP->fDMAMapAlignment)      dataP->fDMAMapAlignment      = data->fMapSpec.alignment;

            remap = (dataP->fDMAMapNumAddressBits < 64)
                 && ((dataP->fMappedBase + _length) > (1ULL << dataP->fDMAMapNumAddressBits));
            remap |= (dataP->fDMAMapAlignment > page_size);
            remap |= (!whole);
            if (remap || !dataP->fMappedBase)
            {
//              if (dataP->fMappedBase) OSReportWithBacktrace("kIOMDDMAMap whole %d remap %d params %d\n", whole, remap, params);
                err = md->dmaMap(data->fMapper, &data->fMapSpec, data->fOffset, data->fLength, &data->fAlloc, &data->fAllocCount);
                if ((kIOReturnSuccess == err) && whole && !dataP->fMappedBase)
                {
                    dataP->fMappedBase = data->fAlloc;
                    data->fAllocCount = 0;                      // IOMD owns the alloc now
                }
            }
            else
            {
                data->fAlloc = dataP->fMappedBase;
                data->fAllocCount = 0;                          // IOMD owns the alloc
            }
            data->fMapContig = !dataP->fDiscontig;
        }

        return (err);                           
    }

    if (kIOMDAddDMAMapSpec == op)
    {
        if (dataSize < sizeof(IODMAMapSpecification))
            return kIOReturnUnderrun;

        IODMAMapSpecification * data = (IODMAMapSpecification *) vData;

        if (!_memoryEntries 
            && !md->initMemoryEntries(computeDataSize(0, 0), kIOMapperWaitSystem)) return (kIOReturnNoMemory);

        if (_memoryEntries)
        {
            dataP = getDataP(_memoryEntries);
            if (data->numAddressBits < dataP->fDMAMapNumAddressBits)
                dataP->fDMAMapNumAddressBits = data->numAddressBits;
            if (data->alignment > dataP->fDMAMapAlignment)
                dataP->fDMAMapAlignment = data->alignment;
        }
        return kIOReturnSuccess;
    }

    if (kIOMDGetCharacteristics == op) {

        if (dataSize < sizeof(IOMDDMACharacteristics))
            return kIOReturnUnderrun;

        IOMDDMACharacteristics *data = (IOMDDMACharacteristics *) vData;
        data->fLength = _length;
        data->fSGCount = _rangesCount;
        data->fPages = _pages;
        data->fDirection = getDirection();
        if (!_wireCount)
            data->fIsPrepared = false;
        else {
            data->fIsPrepared = true;
            data->fHighestPage = _highestPage;
            if (_memoryEntries)
            {
                dataP = getDataP(_memoryEntries);
                ioPLBlock *ioplList = getIOPLList(dataP);
                UInt count = getNumIOPL(_memoryEntries, dataP);
                if (count == 1)
                    data->fPageAlign = (ioplList[0].fPageOffset & PAGE_MASK) | ~PAGE_MASK;
            }
        }

        return kIOReturnSuccess;

#if IOMD_DEBUG_DMAACTIVE
    } else if (kIOMDDMAActive == op) {
        if (params) OSIncrementAtomic(&md->__iomd_reservedA);
        else {
            if (md->__iomd_reservedA)
                OSDecrementAtomic(&md->__iomd_reservedA);
            else
                panic("kIOMDSetDMAInactive");
        }
#endif /* IOMD_DEBUG_DMAACTIVE */

    } else if (kIOMDWalkSegments != op)
        return kIOReturnBadArgument;

    // Get the next segment
    struct InternalState {
        IOMDDMAWalkSegmentArgs fIO;
        UInt fOffset2Index;
        UInt fIndex;
        UInt fNextOffset;
    } *isP;

    // Find the next segment
    if (dataSize < sizeof(*isP))
        return kIOReturnUnderrun;

    isP = (InternalState *) vData;
    UInt offset = isP->fIO.fOffset;
    bool mapped = isP->fIO.fMapped;

    if (IOMapper::gSystem && mapped
        && (!(kIOMemoryHostOnly & _flags))
        && (!_memoryEntries || !getDataP(_memoryEntries)->fMappedBase))
//      && (_memoryEntries && !getDataP(_memoryEntries)->fMappedBase))
    {
        if (!_memoryEntries 
            && !md->initMemoryEntries(computeDataSize(0, 0), kIOMapperWaitSystem)) return (kIOReturnNoMemory);

        dataP = getDataP(_memoryEntries);
        if (dataP->fMapper)
        {
            IODMAMapSpecification mapSpec;
            bzero(&mapSpec, sizeof(mapSpec));
            mapSpec.numAddressBits = dataP->fDMAMapNumAddressBits;
            mapSpec.alignment = dataP->fDMAMapAlignment;
            err = md->dmaMap(dataP->fMapper, &mapSpec, 0, _length, &dataP->fMappedBase, NULL);
            if (kIOReturnSuccess != err) return (err);
        }
    }

    if (offset >= _length)
        return (offset == _length)? kIOReturnOverrun : kIOReturnInternalError;

    // Validate the previous offset
    UInt ind, off2Ind = isP->fOffset2Index;
    if (!params
        && offset 
        && (offset == isP->fNextOffset || off2Ind <= offset))
        ind = isP->fIndex;
    else
        ind = off2Ind = 0;      // Start from beginning

    UInt length;
    UInt64 address;


    if ( (_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical) {

        // Physical address based memory descriptor
        const IOPhysicalRange *physP = (IOPhysicalRange *) &_ranges.p[0];

        // Find the range after the one that contains the offset
        mach_vm_size_t len;
        for (len = 0; off2Ind <= offset; ind++) {
            len = physP[ind].length;
            off2Ind += len;
        }

        // Calculate length within range and starting address
        length   = off2Ind - offset;
        address  = physP[ind - 1].address + len - length;

        if (true && mapped && _memoryEntries 
                && (dataP = getDataP(_memoryEntries)) && dataP->fMappedBase)
        {
            address = dataP->fMappedBase + offset;
        }
        else
        {
            // see how far we can coalesce ranges
            while (ind < _rangesCount && address + length == physP[ind].address) {
                len = physP[ind].length;
                length += len;
                off2Ind += len;
                ind++;
            }
        }

        // correct contiguous check overshoot
        ind--;
        off2Ind -= len;
    }
#ifndef __LP64__
    else if ( (_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical64) {

        // Physical address based memory descriptor
        const IOAddressRange *physP = (IOAddressRange *) &_ranges.v64[0];

        // Find the range after the one that contains the offset
        mach_vm_size_t len;
        for (len = 0; off2Ind <= offset; ind++) {
            len = physP[ind].length;
            off2Ind += len;
        }

        // Calculate length within range and starting address
        length   = off2Ind - offset;
        address  = physP[ind - 1].address + len - length;

        if (true && mapped && _memoryEntries 
                && (dataP = getDataP(_memoryEntries)) && dataP->fMappedBase)
        {
            address = dataP->fMappedBase + offset;
        }
        else
        {
            // see how far we can coalesce ranges
            while (ind < _rangesCount && address + length == physP[ind].address) {
                len = physP[ind].length;
                length += len;
                off2Ind += len;
                ind++;
            }
        }
        // correct contiguous check overshoot
        ind--;
        off2Ind -= len;
    } 
#endif /* !__LP64__ */
    else do {
        if (!_wireCount)
            panic("IOGMD: not wired for the IODMACommand");

        assert(_memoryEntries);

        dataP = getDataP(_memoryEntries);
        const ioPLBlock *ioplList = getIOPLList(dataP);
        UInt numIOPLs = getNumIOPL(_memoryEntries, dataP);
        upl_page_info_t *pageList = getPageList(dataP);

        assert(numIOPLs > 0);

        // Scan through iopl info blocks looking for block containing offset
        while (ind < numIOPLs && offset >= ioplList[ind].fIOMDOffset)
            ind++;

        // Go back to actual range as search goes past it
        ioPLBlock ioplInfo = ioplList[ind - 1];
        off2Ind = ioplInfo.fIOMDOffset;

        if (ind < numIOPLs)
            length = ioplList[ind].fIOMDOffset;
        else
            length = _length;
        length -= offset;                       // Remainder within iopl

        // Subtract offset till this iopl in total list
        offset -= off2Ind;

        // If a mapped address is requested and this is a pre-mapped IOPL
        // then just need to compute an offset relative to the mapped base.
        if (mapped && dataP->fMappedBase) {
            offset += (ioplInfo.fPageOffset & PAGE_MASK);
            address = trunc_page_64(dataP->fMappedBase) + ptoa_64(ioplInfo.fMappedPage) + offset;
            continue;   // Done leave do/while(false) now
        }

        // The offset is rebased into the current iopl.
        // Now add the iopl 1st page offset.
        offset += ioplInfo.fPageOffset;

        // For external UPLs the fPageInfo field points directly to
        // the upl's upl_page_info_t array.
        if (ioplInfo.fFlags & kIOPLExternUPL)
            pageList = (upl_page_info_t *) ioplInfo.fPageInfo;
        else
            pageList = &pageList[ioplInfo.fPageInfo];

        // Check for direct device non-paged memory
        if ( ioplInfo.fFlags & kIOPLOnDevice ) {
            address = ptoa_64(pageList->phys_addr) + offset;
            continue;   // Done leave do/while(false) now
        }

        // Now we need compute the index into the pageList
        UInt pageInd = atop_32(offset);
        offset &= PAGE_MASK;

        // Compute the starting address of this segment
        IOPhysicalAddress pageAddr = pageList[pageInd].phys_addr;
        if (!pageAddr) {
            panic("!pageList phys_addr");
        }

        address = ptoa_64(pageAddr) + offset;

        // length is currently set to the length of the remainider of the iopl.
        // We need to check that the remainder of the iopl is contiguous.
        // This is indicated by pageList[ind].phys_addr being sequential.
        IOByteCount contigLength = PAGE_SIZE - offset;
        while (contigLength < length
                && ++pageAddr == pageList[++pageInd].phys_addr)
        {
            contigLength += PAGE_SIZE;
        }

        if (contigLength < length)
            length = contigLength;
        

        assert(address);
        assert(length);

    } while (false);

    // Update return values and state
    isP->fIO.fIOVMAddr = address;
    isP->fIO.fLength   = length;
    isP->fIndex        = ind;
    isP->fOffset2Index = off2Ind;
    isP->fNextOffset   = isP->fIO.fOffset + length;

    return kIOReturnSuccess;
}

addr64_t
IOGeneralMemoryDescriptor::getPhysicalSegment(IOByteCount offset, IOByteCount *lengthOfSegment, IOOptionBits options)
{
    IOReturn     ret;
    addr64_t     address = 0;
    IOByteCount  length  = 0;
    IOMapper *   mapper  = gIOSystemMapper;
    IOOptionBits type    = _flags & kIOMemoryTypeMask;

    if (lengthOfSegment)
        *lengthOfSegment = 0;

    if (offset >= _length)
        return 0;

    // IOMemoryDescriptor::doMap() cannot use getPhysicalSegment() to obtain the page offset, since it must
    // support the unwired memory case in IOGeneralMemoryDescriptor, and hibernate_write_image() cannot use
    // map()->getVirtualAddress() to obtain the kernel pointer, since it must prevent the memory allocation
    // due to IOMemoryMap, so _kIOMemorySourceSegment is a necessary evil until all of this gets cleaned up

    if ((options & _kIOMemorySourceSegment) && (kIOMemoryTypeUPL != type))
    {
        unsigned rangesIndex = 0;
        Ranges vec = _ranges;
        user_addr_t addr;

        // Find starting address within the vector of ranges
        for (;;) {
            getAddrLenForInd(addr, length, type, vec, rangesIndex);
            if (offset < length)
                break;
            offset -= length; // (make offset relative)
            rangesIndex++;
        } 

        // Now that we have the starting range,
        // lets find the last contiguous range
        addr   += offset;
        length -= offset;

        for ( ++rangesIndex; rangesIndex < _rangesCount; rangesIndex++ ) {
            user_addr_t      newAddr;
            IOPhysicalLength newLen;

            getAddrLenForInd(newAddr, newLen, type, vec, rangesIndex);
            if (addr + length != newAddr)
                break;
            length += newLen;
        } 
        if (addr)
            address = (IOPhysicalAddress) addr; // Truncate address to 32bit
    }
    else
    {
        IOMDDMAWalkSegmentState _state;
        IOMDDMAWalkSegmentArgs * state = (IOMDDMAWalkSegmentArgs *) (void *)&_state;

        state->fOffset = offset;
        state->fLength = _length - offset;
        state->fMapped = (0 == (options & kIOMemoryMapperNone)) && !(_flags & kIOMemoryHostOnly);

        ret = dmaCommandOperation(kIOMDFirstSegment, _state, sizeof(_state));

        if ((kIOReturnSuccess != ret) && (kIOReturnOverrun != ret))
                DEBG("getPhysicalSegment dmaCommandOperation(%lx), %p, offset %qx, addr %qx, len %qx\n", 
                                        ret, this, state->fOffset,
                                        state->fIOVMAddr, state->fLength);
        if (kIOReturnSuccess == ret)
        {
            address = state->fIOVMAddr;
            length  = state->fLength;
        }

        // dmaCommandOperation() does not distinguish between "mapped" and "unmapped" physical memory, even
        // with fMapped set correctly, so we must handle the transformation here until this gets cleaned up

        if (mapper && ((kIOMemoryTypePhysical == type) || (kIOMemoryTypePhysical64 == type)))
        {
            if ((options & kIOMemoryMapperNone) && !(_flags & kIOMemoryMapperNone))
            {
                addr64_t    origAddr = address;
                IOByteCount origLen  = length;

                address = mapper->mapAddr(origAddr);
                length = page_size - (address & (page_size - 1));
                while ((length < origLen)
                    && ((address + length) == mapper->mapAddr(origAddr + length)))
                    length += page_size;
                if (length > origLen)
                    length = origLen;
            }
        }
    }

    if (!address)
        length = 0;

    if (lengthOfSegment)
        *lengthOfSegment = length;

    return (address);
}

#ifndef __LP64__
addr64_t
IOMemoryDescriptor::getPhysicalSegment(IOByteCount offset, IOByteCount *lengthOfSegment, IOOptionBits options)
{
    addr64_t address = 0;

    if (options & _kIOMemorySourceSegment)
    {
        address = getSourceSegment(offset, lengthOfSegment);
    }
    else if (options & kIOMemoryMapperNone)
    {
        address = getPhysicalSegment64(offset, lengthOfSegment);
    }
    else
    {
        address = getPhysicalSegment(offset, lengthOfSegment);
    }

    return (address);
}

addr64_t
IOGeneralMemoryDescriptor::getPhysicalSegment64(IOByteCount offset, IOByteCount *lengthOfSegment)
{
    return (getPhysicalSegment(offset, lengthOfSegment, kIOMemoryMapperNone));
}

IOPhysicalAddress
IOGeneralMemoryDescriptor::getPhysicalSegment(IOByteCount offset, IOByteCount *lengthOfSegment)
{
    addr64_t    address = 0;
    IOByteCount length  = 0;

    address = getPhysicalSegment(offset, lengthOfSegment, 0);

    if (lengthOfSegment)
        length = *lengthOfSegment;

    if ((address + length) > 0x100000000ULL)
    {
        panic("getPhysicalSegment() out of 32b range 0x%qx, len 0x%lx, class %s",
                    address, (long) length, (getMetaClass())->getClassName());
    }

    return ((IOPhysicalAddress) address);
}

addr64_t
IOMemoryDescriptor::getPhysicalSegment64(IOByteCount offset, IOByteCount *lengthOfSegment)
{
    IOPhysicalAddress phys32;
    IOByteCount       length;
    addr64_t          phys64;
    IOMapper *        mapper = 0;

    phys32 = getPhysicalSegment(offset, lengthOfSegment);
    if (!phys32)
        return 0;

    if (gIOSystemMapper)
        mapper = gIOSystemMapper;

    if (mapper)
    {
        IOByteCount origLen;

        phys64 = mapper->mapAddr(phys32);
        origLen = *lengthOfSegment;
        length = page_size - (phys64 & (page_size - 1));
        while ((length < origLen)
            && ((phys64 + length) == mapper->mapAddr(phys32 + length)))
            length += page_size;
        if (length > origLen)
            length = origLen;

        *lengthOfSegment = length;
    }
    else
        phys64 = (addr64_t) phys32;

    return phys64;
}

IOPhysicalAddress
IOMemoryDescriptor::getPhysicalSegment(IOByteCount offset, IOByteCount *lengthOfSegment)
{
    return ((IOPhysicalAddress) getPhysicalSegment(offset, lengthOfSegment, 0));
}

IOPhysicalAddress
IOGeneralMemoryDescriptor::getSourceSegment(IOByteCount offset, IOByteCount *lengthOfSegment)
{
    return ((IOPhysicalAddress) getPhysicalSegment(offset, lengthOfSegment, _kIOMemorySourceSegment));
}

void * IOGeneralMemoryDescriptor::getVirtualSegment(IOByteCount offset,
                                                        IOByteCount * lengthOfSegment)
{
    if (_task == kernel_task)
        return (void *) getSourceSegment(offset, lengthOfSegment);
    else
        panic("IOGMD::getVirtualSegment deprecated");

    return 0;
}
#endif /* !__LP64__ */

IOReturn 
IOMemoryDescriptor::dmaCommandOperation(DMACommandOps op, void *vData, UInt dataSize) const
{
    IOMemoryDescriptor *md = const_cast<IOMemoryDescriptor *>(this);
    DMACommandOps params;
    IOReturn err;

    params = (op & ~kIOMDDMACommandOperationMask & op);
    op &= kIOMDDMACommandOperationMask;

    if (kIOMDGetCharacteristics == op) {
        if (dataSize < sizeof(IOMDDMACharacteristics))
            return kIOReturnUnderrun;

        IOMDDMACharacteristics *data = (IOMDDMACharacteristics *) vData;
        data->fLength = getLength();
        data->fSGCount = 0;
        data->fDirection = getDirection();
        data->fIsPrepared = true;       // Assume prepared - fails safe
    }
    else if (kIOMDWalkSegments == op) {
        if (dataSize < sizeof(IOMDDMAWalkSegmentArgs))
            return kIOReturnUnderrun;

        IOMDDMAWalkSegmentArgs *data = (IOMDDMAWalkSegmentArgs *) vData;
        IOByteCount offset  = (IOByteCount) data->fOffset;

        IOPhysicalLength length;
        if (data->fMapped && IOMapper::gSystem)
            data->fIOVMAddr = md->getPhysicalSegment(offset, &length);
        else
            data->fIOVMAddr = md->getPhysicalSegment(offset, &length, kIOMemoryMapperNone);
        data->fLength = length;
    }
    else if (kIOMDAddDMAMapSpec == op) return kIOReturnUnsupported;
    else if (kIOMDDMAMap == op)
    {
        if (dataSize < sizeof(IOMDDMAMapArgs))
            return kIOReturnUnderrun;
        IOMDDMAMapArgs * data = (IOMDDMAMapArgs *) vData;

        if (params) panic("class %s does not support IODMACommand::kIterateOnly", getMetaClass()->getClassName());

        data->fMapContig = true;
        err = md->dmaMap(data->fMapper, &data->fMapSpec, data->fOffset, data->fLength, &data->fAlloc, &data->fAllocCount);
        return (err);                           
    }
    else return kIOReturnBadArgument;

    return kIOReturnSuccess;
}

static IOReturn 
purgeableControlBits(IOOptionBits newState, vm_purgable_t * control, int * state)
{
    IOReturn err = kIOReturnSuccess;

    *control = VM_PURGABLE_SET_STATE;

    enum { kIOMemoryPurgeableControlMask = 15 };

    switch (kIOMemoryPurgeableControlMask & newState)
    {
        case kIOMemoryPurgeableKeepCurrent:
            *control = VM_PURGABLE_GET_STATE;
            break;

        case kIOMemoryPurgeableNonVolatile:
            *state = VM_PURGABLE_NONVOLATILE;
            break;
        case kIOMemoryPurgeableVolatile:
            *state = VM_PURGABLE_VOLATILE | (newState & ~kIOMemoryPurgeableControlMask);
            break;
        case kIOMemoryPurgeableEmpty:
            *state = VM_PURGABLE_EMPTY;
            break;
        default:
            err = kIOReturnBadArgument;
            break;
    }
    return (err);
}

static IOReturn 
purgeableStateBits(int * state)
{
    IOReturn err = kIOReturnSuccess;

    switch (VM_PURGABLE_STATE_MASK & *state)
    {
        case VM_PURGABLE_NONVOLATILE:
            *state = kIOMemoryPurgeableNonVolatile;
            break;
        case VM_PURGABLE_VOLATILE:
            *state = kIOMemoryPurgeableVolatile;
            break;
        case VM_PURGABLE_EMPTY:
            *state = kIOMemoryPurgeableEmpty;
            break;
        default:
            *state = kIOMemoryPurgeableNonVolatile;
            err = kIOReturnNotReady;
            break;
    }
    return (err);
}

IOReturn 
IOGeneralMemoryDescriptor::setPurgeable( IOOptionBits newState,
                                                   IOOptionBits * oldState )
{
    IOReturn      err = kIOReturnSuccess;
    vm_purgable_t control;
    int           state;

    if (_memEntry)
    {
        err = super::setPurgeable(newState, oldState);
    }
    else
    {
        if (kIOMemoryThreadSafe & _flags)
            LOCK;
        do
        {
            // Find the appropriate vm_map for the given task
            vm_map_t curMap;
            if (_task == kernel_task && (kIOMemoryBufferPageable & _flags))
            {
                err = kIOReturnNotReady;
                break;
            }
            else if (!_task)
            {
                err = kIOReturnUnsupported;
                break;
            }
            else
                curMap = get_task_map(_task);

            // can only do one range
            Ranges vec = _ranges;
            IOOptionBits type = _flags & kIOMemoryTypeMask;
            user_addr_t addr; 
            IOByteCount len;
            getAddrLenForInd(addr, len, type, vec, 0);

            err = purgeableControlBits(newState, &control, &state);
            if (kIOReturnSuccess != err)
                break;
            err = mach_vm_purgable_control(curMap, addr, control, &state);
            if (oldState)
            {
                if (kIOReturnSuccess == err)
                {
                    err = purgeableStateBits(&state);
                    *oldState = state;
                }
            }
        }
        while (false);
        if (kIOMemoryThreadSafe & _flags)
            UNLOCK;
    }
    return (err);
}

IOReturn IOMemoryDescriptor::setPurgeable( IOOptionBits newState,
                                           IOOptionBits * oldState )
{
    IOReturn      err = kIOReturnSuccess;
    vm_purgable_t control;
    int           state;

    if (kIOMemoryThreadSafe & _flags)
        LOCK;

    do 
    {
        if (!_memEntry)
        {
            err = kIOReturnNotReady;
            break;
        }
        err = purgeableControlBits(newState, &control, &state);
        if (kIOReturnSuccess != err)
            break;
        err = mach_memory_entry_purgable_control((ipc_port_t) _memEntry, control, &state);
        if (oldState)
        {
            if (kIOReturnSuccess == err)
            {
                err = purgeableStateBits(&state);
                *oldState = state;
            }
        }
    }
    while (false);

    if (kIOMemoryThreadSafe & _flags)
        UNLOCK;

    return (err);
}

 
IOReturn IOMemoryDescriptor::getPageCounts( IOByteCount * residentPageCount,
                                            IOByteCount * dirtyPageCount )
{
   IOReturn err = kIOReturnSuccess;
   unsigned int _residentPageCount, _dirtyPageCount;

   if (kIOMemoryThreadSafe & _flags) LOCK;

    do 
    {
       if (!_memEntry)
       {
           err = kIOReturnNotReady;
           break;
       }
       if ((residentPageCount == NULL) && (dirtyPageCount == NULL))
       {
           err = kIOReturnBadArgument;
           break;
       }

       err = mach_memory_entry_get_page_counts((ipc_port_t) _memEntry, 
                                                residentPageCount ? &_residentPageCount : NULL,
                                                dirtyPageCount    ? &_dirtyPageCount    : NULL);
       if (kIOReturnSuccess != err) break;
       if (residentPageCount) *residentPageCount = _residentPageCount;
       if (dirtyPageCount)    *dirtyPageCount    = _dirtyPageCount;
    }
    while (false);

    if (kIOMemoryThreadSafe & _flags) UNLOCK;

    return (err);
}
 

extern "C" void dcache_incoherent_io_flush64(addr64_t pa, unsigned int count);
extern "C" void dcache_incoherent_io_store64(addr64_t pa, unsigned int count);

static void SetEncryptOp(addr64_t pa, unsigned int count)
{
    ppnum_t page, end;

    page = atop_64(round_page_64(pa));
    end  = atop_64(trunc_page_64(pa + count));
    for (; page < end; page++)
    {
        pmap_clear_noencrypt(page);    
    }
}

static void ClearEncryptOp(addr64_t pa, unsigned int count)
{
    ppnum_t page, end;

    page = atop_64(round_page_64(pa));
    end  = atop_64(trunc_page_64(pa + count));
    for (; page < end; page++)
    {
        pmap_set_noencrypt(page);    
    }
}

IOReturn IOMemoryDescriptor::performOperation( IOOptionBits options,
                                                IOByteCount offset, IOByteCount length )
{
    IOByteCount remaining;
    unsigned int res;
    void (*func)(addr64_t pa, unsigned int count) = 0;

    switch (options)
    {
        case kIOMemoryIncoherentIOFlush:
            func = &dcache_incoherent_io_flush64;
            break;
        case kIOMemoryIncoherentIOStore:
            func = &dcache_incoherent_io_store64;
            break;

        case kIOMemorySetEncrypted:
            func = &SetEncryptOp;
            break;
        case kIOMemoryClearEncrypted:
            func = &ClearEncryptOp;
            break;
    }

    if (!func)
        return (kIOReturnUnsupported);

    if (kIOMemoryThreadSafe & _flags)
        LOCK;

    res = 0x0UL;
    remaining = length = min(length, getLength() - offset);
    while (remaining)
    // (process another target segment?)
    {
        addr64_t    dstAddr64;
        IOByteCount dstLen;

        dstAddr64 = getPhysicalSegment(offset, &dstLen, kIOMemoryMapperNone);
        if (!dstAddr64)
            break;

        // Clip segment length to remaining
        if (dstLen > remaining)
            dstLen = remaining;

        (*func)(dstAddr64, dstLen);

        offset    += dstLen;
        remaining -= dstLen;
    }

    if (kIOMemoryThreadSafe & _flags)
        UNLOCK;

    return (remaining ? kIOReturnUnderrun : kIOReturnSuccess);
}

#if defined(__i386__) || defined(__x86_64__)
extern vm_offset_t              first_avail;
#define io_kernel_static_end    first_avail
#else
#error io_kernel_static_end is undefined for this architecture
#endif

static kern_return_t
io_get_kernel_static_upl(
        vm_map_t                /* map */,
        uintptr_t               offset,
        vm_size_t               *upl_size,
        upl_t                   *upl,
        upl_page_info_array_t   page_list,
        unsigned int            *count,
        ppnum_t                 *highest_page)
{
    unsigned int pageCount, page;
    ppnum_t phys;
    ppnum_t highestPage = 0;

    pageCount = atop_32(*upl_size);
    if (pageCount > *count)
        pageCount = *count;

    *upl = NULL;

    for (page = 0; page < pageCount; page++)
    {
        phys = pmap_find_phys(kernel_pmap, ((addr64_t)offset) + ptoa_64(page));
        if (!phys)
            break;
        page_list[page].phys_addr = phys;
        page_list[page].pageout   = 0;
        page_list[page].absent    = 0;
        page_list[page].dirty     = 0;
        page_list[page].precious  = 0;
        page_list[page].device    = 0;
        if (phys > highestPage)
            highestPage = phys;
    }

    *highest_page = highestPage;

    return ((page >= pageCount) ? kIOReturnSuccess : kIOReturnVMError);
}

IOReturn IOGeneralMemoryDescriptor::wireVirtual(IODirection forDirection)
{
    IOOptionBits type = _flags & kIOMemoryTypeMask;
    IOReturn error = kIOReturnCannotWire;
    ioGMDData *dataP;
    upl_page_info_array_t pageInfo;
    ppnum_t mapBase;
    ipc_port_t sharedMem;

    assert(kIOMemoryTypeVirtual == type || kIOMemoryTypeVirtual64 == type || kIOMemoryTypeUIO == type);

    if ((kIODirectionOutIn & forDirection) == kIODirectionNone)
        forDirection = (IODirection) (forDirection | getDirection());

    int uplFlags;    // This Mem Desc's default flags for upl creation
    switch (kIODirectionOutIn & forDirection)
    {
    case kIODirectionOut:
        // Pages do not need to be marked as dirty on commit
        uplFlags = UPL_COPYOUT_FROM;
        break;

    case kIODirectionIn:
    default:
        uplFlags = 0;   // i.e. ~UPL_COPYOUT_FROM
        break;
    }

    if (_wireCount)
    {
        if ((kIOMemoryPreparedReadOnly & _flags) && !(UPL_COPYOUT_FROM & uplFlags))
        {
            OSReportWithBacktrace("IOMemoryDescriptor 0x%lx prepared read only", VM_KERNEL_ADDRPERM(this));
            error = kIOReturnNotWritable;
        }
        else error = kIOReturnSuccess;
        return (error);
    }

    dataP = getDataP(_memoryEntries);
    IOMapper *mapper;
    mapper = dataP->fMapper;
    dataP->fMappedBase = 0;

    uplFlags |= UPL_SET_IO_WIRE | UPL_SET_LITE;
    if (kIODirectionPrepareToPhys32 & forDirection) 
    {
        if (!mapper) uplFlags |= UPL_NEED_32BIT_ADDR;
        if (dataP->fDMAMapNumAddressBits > 32) dataP->fDMAMapNumAddressBits = 32;
    }
    if (kIODirectionPrepareNoFault    & forDirection) uplFlags |= UPL_REQUEST_NO_FAULT;
    if (kIODirectionPrepareNoZeroFill & forDirection) uplFlags |= UPL_NOZEROFILLIO;

    mapBase = 0;
    sharedMem = (ipc_port_t) _memEntry;

    // Note that appendBytes(NULL) zeros the data up to the desired length.
    _memoryEntries->appendBytes(0, dataP->fPageCnt * sizeof(upl_page_info_t));
    dataP = 0;

    // Find the appropriate vm_map for the given task
    vm_map_t curMap;
    if (_task == kernel_task && (kIOMemoryBufferPageable & _flags))
        curMap = 0;
    else
        { curMap = get_task_map(_task); }

    // Iterate over the vector of virtual ranges
    Ranges vec = _ranges;
    unsigned int pageIndex  = 0;
    IOByteCount mdOffset    = 0;
    ppnum_t highestPage     = 0;

    for (UInt range = 0; range < _rangesCount; range++) {
        ioPLBlock iopl;
        user_addr_t startPage;
        IOByteCount numBytes;
        ppnum_t highPage = 0;

        // Get the startPage address and length of vec[range]
        getAddrLenForInd(startPage, numBytes, type, vec, range);
        iopl.fPageOffset = startPage & PAGE_MASK;
        numBytes += iopl.fPageOffset;
        startPage = trunc_page_64(startPage);

        if (mapper)
            iopl.fMappedPage = mapBase + pageIndex;
        else
            iopl.fMappedPage = 0;

        // Iterate over the current range, creating UPLs
        while (numBytes) {
            vm_address_t kernelStart = (vm_address_t) startPage;
            vm_map_t theMap;
            if (curMap)
                theMap = curMap;
            else if (!sharedMem) {
                assert(_task == kernel_task);
                theMap = IOPageableMapForAddress(kernelStart);
            }
            else
                theMap = NULL;

            int ioplFlags = uplFlags;
            dataP = getDataP(_memoryEntries);
            pageInfo = getPageList(dataP);
            upl_page_list_ptr_t baseInfo = &pageInfo[pageIndex];

            vm_size_t ioplSize = round_page(numBytes);
            unsigned int numPageInfo = atop_32(ioplSize);

            if (theMap == kernel_map && kernelStart < io_kernel_static_end) {
                error = io_get_kernel_static_upl(theMap, 
                                                kernelStart,
                                                &ioplSize,
                                                &iopl.fIOPL,
                                                baseInfo,
                                                &numPageInfo,
                                                &highPage);
            }
            else if (sharedMem) {
                error = memory_object_iopl_request(sharedMem, 
                                                ptoa_32(pageIndex),
                                                &ioplSize,
                                                &iopl.fIOPL,
                                                baseInfo,
                                                &numPageInfo,
                                                &ioplFlags);
            }
            else {
                assert(theMap);
                error = vm_map_create_upl(theMap,
                                                startPage,
                                                (upl_size_t*)&ioplSize,
                                                &iopl.fIOPL,
                                                baseInfo,
                                                &numPageInfo,
                                                &ioplFlags);
            }

            assert(ioplSize);
            if (error != KERN_SUCCESS)
                goto abortExit;

            if (iopl.fIOPL)
                highPage = upl_get_highest_page(iopl.fIOPL);
            if (highPage > highestPage)
                highestPage = highPage;

            error = kIOReturnCannotWire;

            if (baseInfo->device) {
                numPageInfo = 1;
                iopl.fFlags = kIOPLOnDevice;
            }
            else {
                iopl.fFlags = 0;
            }

            iopl.fIOMDOffset = mdOffset;
            iopl.fPageInfo = pageIndex;
            if (mapper && pageIndex && (page_mask & (mdOffset + iopl.fPageOffset))) dataP->fDiscontig = true;

#if 0
            // used to remove the upl for auto prepares here, for some errant code
            // that freed memory before the descriptor pointing at it
            if ((_flags & kIOMemoryAutoPrepare) && iopl.fIOPL)
            {
                upl_commit(iopl.fIOPL, 0, 0);
                upl_deallocate(iopl.fIOPL);
                iopl.fIOPL = 0;
            }
#endif

            if (!_memoryEntries->appendBytes(&iopl, sizeof(iopl))) {
                // Clean up partial created and unsaved iopl
                if (iopl.fIOPL) {
                    upl_abort(iopl.fIOPL, 0);
                    upl_deallocate(iopl.fIOPL);
                }
                goto abortExit;
            }
            dataP = 0;

            // Check for a multiple iopl's in one virtual range
            pageIndex += numPageInfo;
            mdOffset -= iopl.fPageOffset;
            if (ioplSize < numBytes) {
                numBytes -= ioplSize;
                startPage += ioplSize;
                mdOffset += ioplSize;
                iopl.fPageOffset = 0;
                if (mapper) iopl.fMappedPage = mapBase + pageIndex;
            }
            else {
                mdOffset += numBytes;
                break;
            }
        }
    }

    _highestPage = highestPage;

    if (UPL_COPYOUT_FROM & uplFlags) _flags |= kIOMemoryPreparedReadOnly;

    return kIOReturnSuccess;

abortExit:
    {
        dataP = getDataP(_memoryEntries);
        UInt done = getNumIOPL(_memoryEntries, dataP);
        ioPLBlock *ioplList = getIOPLList(dataP);
    
        for (UInt range = 0; range < done; range++)
        {
            if (ioplList[range].fIOPL) {
             upl_abort(ioplList[range].fIOPL, 0);
             upl_deallocate(ioplList[range].fIOPL);
            }
        }
        (void) _memoryEntries->initWithBytes(dataP, computeDataSize(0, 0)); // == setLength()
    }

    if (error == KERN_FAILURE)
        error = kIOReturnCannotWire;
    else if (error == KERN_MEMORY_ERROR)
        error = kIOReturnNoResources;

    return error;
}

bool IOGeneralMemoryDescriptor::initMemoryEntries(size_t size, IOMapper * mapper)
{
    ioGMDData * dataP;
    unsigned    dataSize = size;

    if (!_memoryEntries) {
        _memoryEntries = OSData::withCapacity(dataSize);
        if (!_memoryEntries)
            return false;
    }
    else if (!_memoryEntries->initWithCapacity(dataSize))
        return false;

    _memoryEntries->appendBytes(0, computeDataSize(0, 0));
    dataP = getDataP(_memoryEntries);

    if (mapper == kIOMapperWaitSystem) {
        IOMapper::checkForSystemMapper();
        mapper = IOMapper::gSystem;
    }
    dataP->fMapper               = mapper;
    dataP->fPageCnt              = 0;
    dataP->fMappedBase           = 0;
    dataP->fDMAMapNumAddressBits = 64;
    dataP->fDMAMapAlignment      = 0;
    dataP->fPreparationID        = kIOPreparationIDUnprepared;
    dataP->fDiscontig            = false;

    return (true);
}

IOReturn IOMemoryDescriptor::dmaMap(
    IOMapper                    * mapper,
    const IODMAMapSpecification * mapSpec,
    uint64_t                      offset,
    uint64_t                      length,
    uint64_t                    * address,
    ppnum_t                     * mapPages)
{
    IOMDDMAWalkSegmentState  walkState;
    IOMDDMAWalkSegmentArgs * walkArgs = (IOMDDMAWalkSegmentArgs *) (void *)&walkState;
    IOOptionBits             mdOp;
    IOReturn                 ret;
    IOPhysicalLength         segLen;
    addr64_t                 phys, align, pageOffset;
    ppnum_t                  base, pageIndex, pageCount;
    uint64_t                 index;
    uint32_t                 mapOptions = 0;

    if (!(kIOMemoryPreparedReadOnly & _flags)) mapOptions |= kIODMAMapWriteAccess;

    walkArgs->fMapped = false;
    mdOp = kIOMDFirstSegment;
    pageCount = 0;
    for (index = 0; index < length; )
    {
        if (index && (page_mask & (index + pageOffset))) break;

        walkArgs->fOffset = offset + index;
        ret = dmaCommandOperation(mdOp, &walkState, sizeof(walkState));
        mdOp = kIOMDWalkSegments;
        if (ret != kIOReturnSuccess) break;
        phys = walkArgs->fIOVMAddr;
        segLen = walkArgs->fLength;

        align = (phys & page_mask);
        if (!index) pageOffset = align;
        else if (align) break;
        pageCount += atop_64(round_page_64(align + segLen));
        index += segLen;
    }

    if (index < length) return (kIOReturnVMError);

    base = mapper->iovmMapMemory(this, offset, pageCount, 
                                 mapOptions, NULL, mapSpec);

    if (!base) return (kIOReturnNoResources);

    mdOp = kIOMDFirstSegment;
    for (pageIndex = 0, index = 0; index < length; )
    {
        walkArgs->fOffset = offset + index;
        ret = dmaCommandOperation(mdOp, &walkState, sizeof(walkState));
        mdOp = kIOMDWalkSegments;
        if (ret != kIOReturnSuccess) break;
        phys = walkArgs->fIOVMAddr;
        segLen = walkArgs->fLength;

        ppnum_t page = atop_64(phys);
        ppnum_t count = atop_64(round_page_64(phys + segLen)) - page;
        while (count--)
        {
            mapper->iovmInsert(base, pageIndex, page);
            page++;
            pageIndex++;
        }
        index += segLen;
    }
    if (pageIndex != pageCount) panic("pageIndex");

    *address = ptoa_64(base) + pageOffset;
    if (mapPages) *mapPages = pageCount;

    return (kIOReturnSuccess);
}

IOReturn IOGeneralMemoryDescriptor::dmaMap(
    IOMapper                    * mapper,
    const IODMAMapSpecification * mapSpec,
    uint64_t                      offset,
    uint64_t                      length,
    uint64_t                    * address,
    ppnum_t                     * mapPages)
{
    IOReturn          err = kIOReturnSuccess;
    ioGMDData *       dataP;
    IOOptionBits      type = _flags & kIOMemoryTypeMask;

    *address = 0;
    if (kIOMemoryHostOnly & _flags) return (kIOReturnSuccess);

    if ((type == kIOMemoryTypePhysical) || (type == kIOMemoryTypePhysical64)
     || offset || (length != _length))
    {
        err = super::dmaMap(mapper, mapSpec, offset, length, address, mapPages);
    }
    else if (_memoryEntries && _pages && (dataP = getDataP(_memoryEntries)))
    {
        const ioPLBlock * ioplList = getIOPLList(dataP);
        upl_page_info_t * pageList;
        uint32_t          mapOptions = 0;
        ppnum_t           base;

        IODMAMapSpecification mapSpec;
        bzero(&mapSpec, sizeof(mapSpec));
        mapSpec.numAddressBits = dataP->fDMAMapNumAddressBits;
        mapSpec.alignment = dataP->fDMAMapAlignment;

        // For external UPLs the fPageInfo field points directly to
        // the upl's upl_page_info_t array.
        if (ioplList->fFlags & kIOPLExternUPL)
        {
            pageList = (upl_page_info_t *) ioplList->fPageInfo;
            mapOptions |= kIODMAMapPagingPath;
        }
        else
            pageList = getPageList(dataP);

    if (!(kIOMemoryPreparedReadOnly & _flags)) mapOptions |= kIODMAMapWriteAccess;

        // Check for direct device non-paged memory
        if (ioplList->fFlags & kIOPLOnDevice) mapOptions |= kIODMAMapPhysicallyContiguous;

        base = mapper->iovmMapMemory(
                        this, offset, _pages, mapOptions, &pageList[0], &mapSpec);
        *address = ptoa_64(base) + (ioplList->fPageOffset & PAGE_MASK);
        if (mapPages) *mapPages = _pages;
    }

    return (err);
}

/*
 * prepare
 *
 * Prepare the memory for an I/O transfer.  This involves paging in
 * the memory, if necessary, and wiring it down for the duration of
 * the transfer.  The complete() method completes the processing of
 * the memory after the I/O transfer finishes.  This method needn't
 * called for non-pageable memory.
 */

IOReturn IOGeneralMemoryDescriptor::prepare(IODirection forDirection)
{
    IOReturn error    = kIOReturnSuccess;
    IOOptionBits type = _flags & kIOMemoryTypeMask;

    if ((kIOMemoryTypePhysical == type) || (kIOMemoryTypePhysical64 == type))
        return kIOReturnSuccess;

    if (_prepareLock)
        IOLockLock(_prepareLock);

    if (kIOMemoryTypeVirtual == type || kIOMemoryTypeVirtual64 == type || kIOMemoryTypeUIO == type)
    {
        error = wireVirtual(forDirection);
    }

    if (kIOReturnSuccess == error)
    {
        if (1 == ++_wireCount)
        {
            if (kIOMemoryClearEncrypt & _flags)
            {
                performOperation(kIOMemoryClearEncrypted, 0, _length);
            }
        }
    }

    if (_prepareLock)
        IOLockUnlock(_prepareLock);

    return error;
}

/*
 * complete
 *
 * Complete processing of the memory after an I/O transfer finishes.
 * This method should not be called unless a prepare was previously
 * issued; the prepare() and complete() must occur in pairs, before
 * before and after an I/O transfer involving pageable memory.
 */

IOReturn IOGeneralMemoryDescriptor::complete(IODirection /* forDirection */)
{
    IOOptionBits type = _flags & kIOMemoryTypeMask;

    if ((kIOMemoryTypePhysical == type) || (kIOMemoryTypePhysical64 == type))
        return kIOReturnSuccess;

    if (_prepareLock)
        IOLockLock(_prepareLock);

    assert(_wireCount);

    if (_wireCount)
    {
        if ((kIOMemoryClearEncrypt & _flags) && (1 == _wireCount))
        {
            performOperation(kIOMemorySetEncrypted, 0, _length);
        }

        _wireCount--;
        if (!_wireCount)
        {
            IOOptionBits type = _flags & kIOMemoryTypeMask;
            ioGMDData * dataP = getDataP(_memoryEntries);
            ioPLBlock *ioplList = getIOPLList(dataP);
            UInt count = getNumIOPL(_memoryEntries, dataP);

#if IOMD_DEBUG_DMAACTIVE
            if (__iomd_reservedA) panic("complete() while dma active");
#endif /* IOMD_DEBUG_DMAACTIVE */

            if (dataP->fMappedBase) {
                dataP->fMapper->iovmFree(atop_64(dataP->fMappedBase), _pages);
                dataP->fMappedBase = 0;
            }
            // Only complete iopls that we created which are for TypeVirtual
            if (kIOMemoryTypeVirtual == type || kIOMemoryTypeVirtual64 == type || kIOMemoryTypeUIO == type) {
                for (UInt ind = 0; ind < count; ind++)
                    if (ioplList[ind].fIOPL) {
                         upl_commit(ioplList[ind].fIOPL, 0, 0);
                         upl_deallocate(ioplList[ind].fIOPL);
                    }
            } else if (kIOMemoryTypeUPL == type) {
                upl_set_referenced(ioplList[0].fIOPL, false);
            }

            (void) _memoryEntries->initWithBytes(dataP, computeDataSize(0, 0)); // == setLength()

            dataP->fPreparationID = kIOPreparationIDUnprepared;
        }
    }

    if (_prepareLock)
        IOLockUnlock(_prepareLock);

    return kIOReturnSuccess;
}

IOReturn IOGeneralMemoryDescriptor::doMap(
        vm_map_t                __addressMap,
        IOVirtualAddress *      __address,
        IOOptionBits            options,
        IOByteCount             __offset,
        IOByteCount             __length )

{
#ifndef __LP64__
    if (!(kIOMap64Bit & options)) panic("IOGeneralMemoryDescriptor::doMap !64bit");
#endif /* !__LP64__ */

    IOMemoryMap *  mapping = (IOMemoryMap *) *__address;
    mach_vm_size_t offset  = mapping->fOffset + __offset;
    mach_vm_size_t length  = mapping->fLength;

    kern_return_t kr = kIOReturnVMError;
    ipc_port_t sharedMem = (ipc_port_t) _memEntry;

    IOOptionBits type = _flags & kIOMemoryTypeMask;
    Ranges vec = _ranges;

    user_addr_t range0Addr = 0;
    IOByteCount range0Len = 0;

    if ((offset >= _length) || ((offset + length) > _length))
        return( kIOReturnBadArgument );

    if (vec.v)
        getAddrLenForInd(range0Addr, range0Len, type, vec, 0);

    // mapping source == dest? (could be much better)
    if( _task
     && (mapping->fAddressMap == get_task_map(_task)) && (options & kIOMapAnywhere)
     && (1 == _rangesCount) && (0 == offset)
     && range0Addr && (length <= range0Len) )
    {
        mapping->fAddress = range0Addr;
        mapping->fOptions |= kIOMapStatic;

        return( kIOReturnSuccess );
    }

    if( 0 == sharedMem) {

        vm_size_t size = ptoa_32(_pages);

        if( _task) {

            memory_object_size_t actualSize = size;
            vm_prot_t            prot       = VM_PROT_READ;
            if (!(kIOMapReadOnly & options))
                prot |= VM_PROT_WRITE;
            else if (kIOMapDefaultCache != (options & kIOMapCacheMask))
                prot |= VM_PROT_WRITE;

            if (_rangesCount == 1)
            {
                kr = mach_make_memory_entry_64(get_task_map(_task),
                                                &actualSize, range0Addr,
                                                prot, &sharedMem,
                                                NULL);
            }
            if( (_rangesCount != 1) 
                || ((KERN_SUCCESS == kr) && (actualSize != round_page(size))))
            do
            {
#if IOASSERT
                IOLog("mach_vm_remap path for ranges %d size (%08llx:%08llx)\n",
                      _rangesCount, (UInt64)actualSize, (UInt64)size);
#endif
                kr = kIOReturnVMError;
                if (sharedMem)
                {
                    ipc_port_release_send(sharedMem);
                    sharedMem = MACH_PORT_NULL;
                }

                mach_vm_address_t address, segDestAddr;
                mach_vm_size_t    mapLength;
                unsigned          rangesIndex;
                IOOptionBits      type = _flags & kIOMemoryTypeMask;
                user_addr_t       srcAddr;
                IOPhysicalLength  segLen = 0;

                // Find starting address within the vector of ranges
                for (rangesIndex = 0; rangesIndex < _rangesCount; rangesIndex++) {
                    getAddrLenForInd(srcAddr, segLen, type, _ranges, rangesIndex);
                    if (offset < segLen)
                        break;
                    offset -= segLen; // (make offset relative)
                } 

                mach_vm_size_t    pageOffset = (srcAddr & PAGE_MASK);
                address = trunc_page_64(mapping->fAddress);

                if ((options & kIOMapAnywhere) || ((mapping->fAddress - address) == pageOffset))
                {
                    vm_map_t map = mapping->fAddressMap;
                    kr = IOMemoryDescriptorMapCopy(&map, 
                                                    options,
                                                    offset, &address, round_page_64(length + pageOffset));
                    if (kr == KERN_SUCCESS)
                    {
                        segDestAddr  = address;
                        segLen      -= offset;
                        srcAddr     += offset;
                        mapLength    = length;

                        while (true)
                        {
                            vm_prot_t cur_prot, max_prot;

                            if (segLen > length) segLen = length;
                            kr = mach_vm_remap(map, &segDestAddr, round_page_64(segLen), PAGE_MASK, 
                                                    VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE,
                                                    get_task_map(_task), trunc_page_64(srcAddr),
                                                    FALSE /* copy */,
                                                    &cur_prot,
                                                    &max_prot,
                                                    VM_INHERIT_NONE);
                            if (KERN_SUCCESS == kr)
                            {
                                if ((!(VM_PROT_READ & cur_prot))
                                    || (!(kIOMapReadOnly & options) && !(VM_PROT_WRITE & cur_prot)))
                                {
                                    kr = KERN_PROTECTION_FAILURE;
                                }
                            }
                            if (KERN_SUCCESS != kr)
                                break;
                            segDestAddr += segLen;
                            mapLength   -= segLen;
                            if (!mapLength)
                                break;
                            rangesIndex++;
                            if (rangesIndex >= _rangesCount)
                            {
                                kr = kIOReturnBadArgument;
                                break;
                            }
                            getAddrLenForInd(srcAddr, segLen, type, vec, rangesIndex);
                            if (srcAddr & PAGE_MASK)
                            {
                                kr = kIOReturnBadArgument;
                                break;
                            }
                            if (segLen > mapLength)
                                segLen = mapLength;
                        } 
                        if (KERN_SUCCESS != kr)
                        {
                            mach_vm_deallocate(mapping->fAddressMap, address, round_page_64(length + pageOffset));
                        }
                    }

                    if (KERN_SUCCESS == kr)
                        mapping->fAddress = address + pageOffset;
                    else
                        mapping->fAddress = NULL;
                }
            }
            while (false);
        } 
        else do
        {       // _task == 0, must be physical

            memory_object_t     pager;
            unsigned int        flags = 0;
            addr64_t            pa;
            IOPhysicalLength    segLen;

            pa = getPhysicalSegment( offset, &segLen, kIOMemoryMapperNone );

            if( !getKernelReserved())
                continue;
            reserved->dp.pagerContig = (1 == _rangesCount);
            reserved->dp.memory      = this;

            /*What cache mode do we need*/
            switch(options & kIOMapCacheMask ) {

                case kIOMapDefaultCache:
                default:
                    flags = IODefaultCacheBits(pa);
                    if (DEVICE_PAGER_CACHE_INHIB & flags)
                    {
                        if (DEVICE_PAGER_GUARDED & flags)
                            mapping->fOptions |= kIOMapInhibitCache;
                        else
                            mapping->fOptions |= kIOMapWriteCombineCache;
                    }
                    else if (DEVICE_PAGER_WRITE_THROUGH & flags)
                        mapping->fOptions |= kIOMapWriteThruCache;
                    else
                        mapping->fOptions |= kIOMapCopybackCache;
                    break;
        
                case kIOMapInhibitCache:
                    flags = DEVICE_PAGER_CACHE_INHIB | 
                                    DEVICE_PAGER_COHERENT | DEVICE_PAGER_GUARDED;
                    break;
        
                case kIOMapWriteThruCache:
                    flags = DEVICE_PAGER_WRITE_THROUGH |
                                    DEVICE_PAGER_COHERENT | DEVICE_PAGER_GUARDED;
                    break;

                case kIOMapCopybackCache:
                    flags = DEVICE_PAGER_COHERENT;
                    break;

                case kIOMapWriteCombineCache:
                    flags = DEVICE_PAGER_CACHE_INHIB |
                                    DEVICE_PAGER_COHERENT;
                    break;
            }

            flags |= reserved->dp.pagerContig ? DEVICE_PAGER_CONTIGUOUS : 0;

            pager = device_pager_setup( (memory_object_t) 0, (uintptr_t) reserved, 
                                                                size, flags);
            assert( pager );

            if( pager) {
                kr = mach_memory_object_memory_entry_64( (host_t) 1, false /*internal*/, 
                            size, VM_PROT_READ | VM_PROT_WRITE, pager, &sharedMem );

                assert( KERN_SUCCESS == kr );
                if( KERN_SUCCESS != kr)
                {
                    device_pager_deallocate( pager );
                    pager = MACH_PORT_NULL;
                    sharedMem = MACH_PORT_NULL;
                }
            }
            if( pager && sharedMem)
                reserved->dp.devicePager    = pager;

        } while( false );

        _memEntry = (void *) sharedMem;
    }

    IOReturn result;
    if (0 == sharedMem)
      result = kr;
    else
      result = super::doMap( __addressMap, __address,
                                        options, __offset, __length );

    return( result );
}

IOReturn IOGeneralMemoryDescriptor::doUnmap(
        vm_map_t                addressMap,
        IOVirtualAddress        __address,
        IOByteCount             __length )
{
    return (super::doUnmap(addressMap, __address, __length));
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#undef super
#define super OSObject

OSDefineMetaClassAndStructors( IOMemoryMap, OSObject )

OSMetaClassDefineReservedUnused(IOMemoryMap, 0);
OSMetaClassDefineReservedUnused(IOMemoryMap, 1);
OSMetaClassDefineReservedUnused(IOMemoryMap, 2);
OSMetaClassDefineReservedUnused(IOMemoryMap, 3);
OSMetaClassDefineReservedUnused(IOMemoryMap, 4);
OSMetaClassDefineReservedUnused(IOMemoryMap, 5);
OSMetaClassDefineReservedUnused(IOMemoryMap, 6);
OSMetaClassDefineReservedUnused(IOMemoryMap, 7);

/* ex-inline function implementation */
IOPhysicalAddress IOMemoryMap::getPhysicalAddress()
    { return( getPhysicalSegment( 0, 0 )); }

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

bool IOMemoryMap::init(
        task_t                  intoTask,
        mach_vm_address_t       toAddress,
        IOOptionBits            _options,
        mach_vm_size_t          _offset,
        mach_vm_size_t          _length )
{
    if (!intoTask)
        return( false);

    if (!super::init())
        return(false);

    fAddressMap  = get_task_map(intoTask);
    if (!fAddressMap)
        return(false);
    vm_map_reference(fAddressMap);

    fAddressTask = intoTask;
    fOptions     = _options;
    fLength      = _length;
    fOffset      = _offset;
    fAddress     = toAddress;

    return (true);
}

bool IOMemoryMap::setMemoryDescriptor(IOMemoryDescriptor * _memory, mach_vm_size_t _offset)
{
    if (!_memory)
        return(false);

    if (!fSuperMap)
    {
        if( (_offset + fLength) > _memory->getLength())
            return( false);
        fOffset = _offset;
    }

    _memory->retain();
    if (fMemory)
    {
        if (fMemory != _memory)
            fMemory->removeMapping(this);
        fMemory->release();
    }
    fMemory = _memory;

    return( true );
}

struct IOMemoryDescriptorMapAllocRef
{
    ipc_port_t          sharedMem;
    vm_map_t            map;
    mach_vm_address_t   mapped;
    mach_vm_size_t      size;
    mach_vm_size_t      sourceOffset;
    IOOptionBits        options;
};

static kern_return_t IOMemoryDescriptorMapAlloc(vm_map_t map, void * _ref)
{
    IOMemoryDescriptorMapAllocRef * ref = (IOMemoryDescriptorMapAllocRef *)_ref;
    IOReturn                        err;

    do {
        if( ref->sharedMem)
        {
            vm_prot_t prot = VM_PROT_READ
                            | ((ref->options & kIOMapReadOnly) ? 0 : VM_PROT_WRITE);

            // VM system requires write access to change cache mode
            if (kIOMapDefaultCache != (ref->options & kIOMapCacheMask))
                prot |= VM_PROT_WRITE;

            // set memory entry cache
            vm_prot_t memEntryCacheMode = prot | MAP_MEM_ONLY;
            switch (ref->options & kIOMapCacheMask)
            {
                case kIOMapInhibitCache:
                    SET_MAP_MEM(MAP_MEM_IO, memEntryCacheMode);
                    break;
        
                case kIOMapWriteThruCache:
                    SET_MAP_MEM(MAP_MEM_WTHRU, memEntryCacheMode);
                    break;

                case kIOMapWriteCombineCache:
                    SET_MAP_MEM(MAP_MEM_WCOMB, memEntryCacheMode);
                    break;

                case kIOMapCopybackCache:
                    SET_MAP_MEM(MAP_MEM_COPYBACK, memEntryCacheMode);
                    break;

                case kIOMapCopybackInnerCache:
                    SET_MAP_MEM(MAP_MEM_INNERWBACK, memEntryCacheMode);
                    break;

                case kIOMapDefaultCache:
                default:
                    SET_MAP_MEM(MAP_MEM_NOOP, memEntryCacheMode);
                    break;
            }

            vm_size_t unused = 0;

            err = mach_make_memory_entry( NULL /*unused*/, &unused, 0 /*unused*/, 
                                            memEntryCacheMode, NULL, ref->sharedMem );
            if (KERN_SUCCESS != err)
                IOLog("MAP_MEM_ONLY failed %d\n", err);

            err = mach_vm_map( map,
                            &ref->mapped,
                            ref->size, 0 /* mask */, 
                            (( ref->options & kIOMapAnywhere ) ? VM_FLAGS_ANYWHERE : VM_FLAGS_FIXED)
                            | VM_MAKE_TAG(VM_MEMORY_IOKIT), 
                            ref->sharedMem, ref->sourceOffset,
                            false, // copy
                            prot, // cur
                            prot, // max
                            VM_INHERIT_NONE);

            if( KERN_SUCCESS != err) {
                ref->mapped = 0;
                continue;
            }
            ref->map = map;
        }
        else
        {
            err = mach_vm_allocate(map, &ref->mapped, ref->size,
                            ((ref->options & kIOMapAnywhere) ? VM_FLAGS_ANYWHERE : VM_FLAGS_FIXED)
                            | VM_MAKE_TAG(VM_MEMORY_IOKIT) );
            if( KERN_SUCCESS != err) {
                ref->mapped = 0;
                continue;
            }
            ref->map = map;
            // we have to make sure that these guys don't get copied if we fork.
            err = vm_inherit(map, ref->mapped, ref->size, VM_INHERIT_NONE);
            assert( KERN_SUCCESS == err );
        }
    }
    while( false );

    return( err );
}

kern_return_t 
IOMemoryDescriptorMapMemEntry(vm_map_t * map, ipc_port_t entry, IOOptionBits options, bool pageable,
                                mach_vm_size_t offset, 
                                mach_vm_address_t * address, mach_vm_size_t length)
{
    IOReturn err;
    IOMemoryDescriptorMapAllocRef ref;

    ref.map          = *map;
    ref.sharedMem    = entry;
    ref.sourceOffset = trunc_page_64(offset);
    ref.options      = options;
    ref.size         = length;

    if (options & kIOMapAnywhere)
        // vm_map looks for addresses above here, even when VM_FLAGS_ANYWHERE
        ref.mapped = 0;
    else
        ref.mapped = *address;

    if( ref.sharedMem && (ref.map == kernel_map) && pageable)
        err = IOIteratePageableMaps( ref.size, &IOMemoryDescriptorMapAlloc, &ref );
    else
        err = IOMemoryDescriptorMapAlloc( ref.map, &ref );

    *address = ref.mapped;
    *map     = ref.map;

    return (err);
}

kern_return_t 
IOMemoryDescriptorMapCopy(vm_map_t * map, 
                                IOOptionBits options,
                                mach_vm_size_t offset, 
                                mach_vm_address_t * address, mach_vm_size_t length)
{
    IOReturn err;
    IOMemoryDescriptorMapAllocRef ref;

    ref.map          = *map;
    ref.sharedMem    = NULL;
    ref.sourceOffset = trunc_page_64(offset);
    ref.options      = options;
    ref.size         = length;

    if (options & kIOMapAnywhere)
        // vm_map looks for addresses above here, even when VM_FLAGS_ANYWHERE
        ref.mapped = 0;
    else
        ref.mapped = *address;

    if (ref.map == kernel_map)
        err = IOIteratePageableMaps(ref.size, &IOMemoryDescriptorMapAlloc, &ref);
    else
        err = IOMemoryDescriptorMapAlloc(ref.map, &ref);

    *address = ref.mapped;
    *map     = ref.map;

    return (err);
}

IOReturn IOMemoryDescriptor::doMap(
        vm_map_t                __addressMap,
        IOVirtualAddress *      __address,
        IOOptionBits            options,
        IOByteCount             __offset,
        IOByteCount             __length )
{
#ifndef __LP64__
    if (!(kIOMap64Bit & options)) panic("IOMemoryDescriptor::doMap !64bit");
#endif /* !__LP64__ */

    IOMemoryMap *  mapping = (IOMemoryMap *) *__address;
    mach_vm_size_t offset  = mapping->fOffset + __offset;
    mach_vm_size_t length  = mapping->fLength;

    IOReturn          err = kIOReturnSuccess;
    memory_object_t   pager;
    mach_vm_size_t    pageOffset;
    IOPhysicalAddress sourceAddr;
    unsigned int lock_count;

    do
    {
        sourceAddr = getPhysicalSegment( offset, NULL, _kIOMemorySourceSegment );
        pageOffset = sourceAddr - trunc_page( sourceAddr );

        if( reserved)
            pager = (memory_object_t) reserved->dp.devicePager;
        else
            pager = MACH_PORT_NULL;

        if ((kIOMapReference|kIOMapUnique) == ((kIOMapReference|kIOMapUnique) & options))
        {
            upl_t          redirUPL2;
            vm_size_t      size;
            int            flags;

            if (!_memEntry)
            {
                err = kIOReturnNotReadable;
                continue;
            }

            size = round_page(mapping->fLength + pageOffset);
            flags = UPL_COPYOUT_FROM | UPL_SET_INTERNAL 
                        | UPL_SET_LITE | UPL_SET_IO_WIRE | UPL_BLOCK_ACCESS;

            if (KERN_SUCCESS != memory_object_iopl_request((ipc_port_t) _memEntry, 0, &size, &redirUPL2,
                                            NULL, NULL,
                                            &flags))
                redirUPL2 = NULL;

            for (lock_count = 0;
                 IORecursiveLockHaveLock(gIOMemoryLock);
                 lock_count++) {
              UNLOCK;
            }
            err = upl_transpose(redirUPL2, mapping->fRedirUPL);
            for (;
                 lock_count;
                 lock_count--) {
              LOCK;
            }

            if (kIOReturnSuccess != err)
            {
                IOLog("upl_transpose(%x)\n", err);
                err = kIOReturnSuccess;
            }

            if (redirUPL2)
            {
                upl_commit(redirUPL2, NULL, 0);
                upl_deallocate(redirUPL2);
                redirUPL2 = 0;
            }
            {
                // swap the memEntries since they now refer to different vm_objects
                void * me = _memEntry;
                _memEntry = mapping->fMemory->_memEntry;
                mapping->fMemory->_memEntry = me;
            }
            if (pager)
                err = handleFault( pager, mapping->fAddressMap, mapping->fAddress, offset, length, options );
        }
        else
        {
            mach_vm_address_t address;

            if (!(options & kIOMapAnywhere))
            {
                address = trunc_page_64(mapping->fAddress);
                if( (mapping->fAddress - address) != pageOffset)
                {
                    err = kIOReturnVMError;
                    continue;
                }
            }

            vm_map_t map = mapping->fAddressMap;
            err = IOMemoryDescriptorMapMemEntry(&map, (ipc_port_t) _memEntry,
                                                    options, (kIOMemoryBufferPageable & _flags),
                                                    offset, &address, round_page_64(length + pageOffset));
            if( err != KERN_SUCCESS)
                continue;

            if (!_memEntry || pager)
            {
                err = handleFault( pager, mapping->fAddressMap, address, offset, length, options );
                if (err != KERN_SUCCESS)
                    doUnmap( mapping->fAddressMap, (IOVirtualAddress) mapping, 0 );
            }

#if DEBUG
        if (kIOLogMapping & gIOKitDebug)
            IOLog("mapping(%x) desc %p @ %qx, map %p, address %qx, offset %qx, length %qx\n", 
                  err, this, (uint64_t)sourceAddr, mapping, address, offset, length);
#endif

            if (err == KERN_SUCCESS)
                mapping->fAddress = address + pageOffset;
            else
                mapping->fAddress = NULL;
        }
    }
    while( false );

    return (err);
}

IOReturn IOMemoryDescriptor::handleFault(
        void *                  _pager,
        vm_map_t                addressMap,
        mach_vm_address_t       address,
        mach_vm_size_t          sourceOffset,
        mach_vm_size_t          length,
        IOOptionBits            options )
{
    IOReturn            err = kIOReturnSuccess;
    memory_object_t     pager = (memory_object_t) _pager;
    mach_vm_size_t      size;
    mach_vm_size_t      bytes;
    mach_vm_size_t      page;
    mach_vm_size_t      pageOffset;
    mach_vm_size_t      pagerOffset;
    IOPhysicalLength    segLen;
    addr64_t            physAddr;

    if( !addressMap)
    {
        if( kIOMemoryRedirected & _flags)
        {
#if DEBUG
            IOLog("sleep mem redirect %p, %qx\n", this, sourceOffset);
#endif
            do {
                SLEEP;
            } while( kIOMemoryRedirected & _flags );
        }

        return( kIOReturnSuccess );
    }

    physAddr = getPhysicalSegment( sourceOffset, &segLen, kIOMemoryMapperNone );
    assert( physAddr );
    pageOffset = physAddr - trunc_page_64( physAddr );
    pagerOffset = sourceOffset;

    size = length + pageOffset;
    physAddr -= pageOffset;

    segLen += pageOffset;
    bytes = size;
    do
    {
        // in the middle of the loop only map whole pages
        if( segLen >= bytes)
            segLen = bytes;
        else if( segLen != trunc_page( segLen))
            err = kIOReturnVMError;
        if( physAddr != trunc_page_64( physAddr))
            err = kIOReturnBadArgument;
        if (kIOReturnSuccess != err)
            break;

#if DEBUG
        if( kIOLogMapping & gIOKitDebug)
            IOLog("IOMemoryMap::map(%p) 0x%qx->0x%qx:0x%qx\n",
                addressMap, address + pageOffset, physAddr + pageOffset,
                segLen - pageOffset);
#endif


        if( pager) {
            if( reserved && reserved->dp.pagerContig) {
                IOPhysicalLength        allLen;
                addr64_t                allPhys;

                allPhys = getPhysicalSegment( 0, &allLen, kIOMemoryMapperNone );
                assert( allPhys );
                err = device_pager_populate_object( pager, 0, atop_64(allPhys), round_page(allLen) );
            }
            else
            {

                for( page = 0;
                     (page < segLen) && (KERN_SUCCESS == err);
                     page += page_size)
                {
                    err = device_pager_populate_object(pager, pagerOffset,
                            (ppnum_t)(atop_64(physAddr + page)), page_size);
                    pagerOffset += page_size;
                }
            }
            assert( KERN_SUCCESS == err );
            if( err)
                break;
        }

        // This call to vm_fault causes an early pmap level resolution
        // of the mappings created above for kernel mappings, since
        // faulting in later can't take place from interrupt level.
        /*  *** ALERT *** */
        /*  *** Temporary Workaround *** */

        if ((addressMap == kernel_map) && !(kIOMemoryRedirected & _flags))
        {
                vm_fault(addressMap, 
                         (vm_map_offset_t)address, 
                         VM_PROT_READ|VM_PROT_WRITE, 
                         FALSE, THREAD_UNINT, NULL, 
                         (vm_map_offset_t)0);
        }

        /*  *** Temporary Workaround *** */
        /*  *** ALERT *** */

        sourceOffset += segLen - pageOffset;
        address += segLen;
        bytes -= segLen;
        pageOffset = 0;

    } 
    while (bytes && (physAddr = getPhysicalSegment( sourceOffset, &segLen, kIOMemoryMapperNone )));

    if (bytes)
        err = kIOReturnBadArgument;

    return (err);
}

IOReturn IOMemoryDescriptor::doUnmap(
        vm_map_t                addressMap,
        IOVirtualAddress        __address,
        IOByteCount             __length )
{
    IOReturn          err;
    mach_vm_address_t address;
    mach_vm_size_t    length;

    if (__length)
    {
        address = __address;
        length  = __length;
    }
    else
    {
        addressMap = ((IOMemoryMap *) __address)->fAddressMap;
        address    = ((IOMemoryMap *) __address)->fAddress;
        length     = ((IOMemoryMap *) __address)->fLength;
    }

    if ((addressMap == kernel_map) 
        && ((kIOMemoryBufferPageable & _flags) || !_memEntry))
        addressMap = IOPageableMapForAddress( address );

#if DEBUG
    if( kIOLogMapping & gIOKitDebug)
        IOLog("IOMemoryDescriptor::doUnmap map %p, 0x%qx:0x%qx\n",
                addressMap, address, length );
#endif

    err = mach_vm_deallocate( addressMap, address, length );

    return (err);
}

IOReturn IOMemoryDescriptor::redirect( task_t safeTask, bool doRedirect )
{
    IOReturn            err = kIOReturnSuccess;
    IOMemoryMap *       mapping = 0;
    OSIterator *        iter;

    LOCK;

    if( doRedirect)
        _flags |= kIOMemoryRedirected;
    else
        _flags &= ~kIOMemoryRedirected;

    do {
        if( (iter = OSCollectionIterator::withCollection( _mappings))) {

            memory_object_t   pager;

            if( reserved)
                pager = (memory_object_t) reserved->dp.devicePager;
            else
                pager = MACH_PORT_NULL;

            while( (mapping = (IOMemoryMap *) iter->getNextObject()))
            {
                mapping->redirect( safeTask, doRedirect );
                if (!doRedirect && !safeTask && pager && (kernel_map == mapping->fAddressMap))
                {
                    err = handleFault( pager, mapping->fAddressMap, mapping->fAddress, mapping->fOffset, mapping->fLength, kIOMapDefaultCache );
                }
            }

            iter->release();
        }
    } while( false );

    if (!doRedirect)
    {
        WAKEUP;
    }

    UNLOCK;

#ifndef __LP64__
    // temporary binary compatibility
    IOSubMemoryDescriptor * subMem;
    if( (subMem = OSDynamicCast( IOSubMemoryDescriptor, this)))
        err = subMem->redirect( safeTask, doRedirect );
    else
        err = kIOReturnSuccess;
#endif /* !__LP64__ */

    return( err );
}

IOReturn IOMemoryMap::redirect( task_t safeTask, bool doRedirect )
{
    IOReturn err = kIOReturnSuccess;

    if( fSuperMap) {
//        err = ((IOMemoryMap *)superMap)->redirect( safeTask, doRedirect );
    } else {

        LOCK;

        do
        {
            if (!fAddress)
                break;
            if (!fAddressMap)
                break;

            if ((!safeTask || (get_task_map(safeTask) != fAddressMap))
              && (0 == (fOptions & kIOMapStatic)))
            {
                IOUnmapPages( fAddressMap, fAddress, fLength );
                err = kIOReturnSuccess;
#if DEBUG
                IOLog("IOMemoryMap::redirect(%d, %p) 0x%qx:0x%qx from %p\n", doRedirect, this, fAddress, fLength, fAddressMap);
#endif
            }
            else if (kIOMapWriteCombineCache == (fOptions & kIOMapCacheMask))
            {
                IOOptionBits newMode;
                newMode = (fOptions & ~kIOMapCacheMask) | (doRedirect ? kIOMapInhibitCache : kIOMapWriteCombineCache);
                IOProtectCacheMode(fAddressMap, fAddress, fLength, newMode);
            }
        }
        while (false);
        UNLOCK;
    }

    if ((((fMemory->_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical)
         || ((fMemory->_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical64))
     && safeTask
     && (doRedirect != (0 != (fMemory->_flags & kIOMemoryRedirected))))
        fMemory->redirect(safeTask, doRedirect);

    return( err );
}

IOReturn IOMemoryMap::unmap( void )
{
    IOReturn    err;

    LOCK;

    if( fAddress && fAddressMap && (0 == fSuperMap) && fMemory
        && (0 == (fOptions & kIOMapStatic))) {

        vm_map_iokit_unmapped_region(fAddressMap, fLength);

        err = fMemory->doUnmap(fAddressMap, (IOVirtualAddress) this, 0);

    } else
        err = kIOReturnSuccess;

    if (fAddressMap)
    {
        vm_map_deallocate(fAddressMap);
        fAddressMap = 0;
    }

    fAddress = 0;

    UNLOCK;

    return( err );
}

void IOMemoryMap::taskDied( void )
{
    LOCK;
    if (fUserClientUnmap)
        unmap();
    if( fAddressMap) {
        vm_map_deallocate(fAddressMap);
        fAddressMap = 0;
    }
    fAddressTask = 0;
    fAddress     = 0;
    UNLOCK;
}

IOReturn IOMemoryMap::userClientUnmap( void )
{
    fUserClientUnmap = true;
    return (kIOReturnSuccess);
}

// Overload the release mechanism.  All mappings must be a member
// of a memory descriptors _mappings set.  This means that we
// always have 2 references on a mapping.  When either of these mappings
// are released we need to free ourselves.
void IOMemoryMap::taggedRelease(const void *tag) const
{
    LOCK;
    super::taggedRelease(tag, 2);
    UNLOCK;
}

void IOMemoryMap::free()
{
    unmap();

    if (fMemory)
    {
        LOCK;
        fMemory->removeMapping(this);
        UNLOCK;
        fMemory->release();
    }

    if (fOwner && (fOwner != fMemory))
    {
        LOCK;
        fOwner->removeMapping(this);
        UNLOCK;
    }

    if (fSuperMap)
        fSuperMap->release();

    if (fRedirUPL) {
        upl_commit(fRedirUPL, NULL, 0);
        upl_deallocate(fRedirUPL);
    }

    super::free();
}

IOByteCount IOMemoryMap::getLength()
{
    return( fLength );
}

IOVirtualAddress IOMemoryMap::getVirtualAddress()
{
#ifndef __LP64__
    if (fSuperMap)
        fSuperMap->getVirtualAddress();
    else if (fAddressMap 
                && vm_map_is_64bit(fAddressMap)
                && (sizeof(IOVirtualAddress) < 8))
    {
        OSReportWithBacktrace("IOMemoryMap::getVirtualAddress(0x%qx) called on 64b map; use ::getAddress()", fAddress);
    }
#endif /* !__LP64__ */

    return (fAddress);
}

#ifndef __LP64__
mach_vm_address_t       IOMemoryMap::getAddress()
{
    return( fAddress);
}

mach_vm_size_t  IOMemoryMap::getSize()
{
    return( fLength );
}
#endif /* !__LP64__ */


task_t IOMemoryMap::getAddressTask()
{
    if( fSuperMap)
        return( fSuperMap->getAddressTask());
    else
        return( fAddressTask);
}

IOOptionBits IOMemoryMap::getMapOptions()
{
    return( fOptions);
}

IOMemoryDescriptor * IOMemoryMap::getMemoryDescriptor()
{
    return( fMemory );
}

IOMemoryMap * IOMemoryMap::copyCompatible(
                IOMemoryMap * newMapping )
{
    task_t              task      = newMapping->getAddressTask();
    mach_vm_address_t   toAddress = newMapping->fAddress;
    IOOptionBits        _options  = newMapping->fOptions;
    mach_vm_size_t      _offset   = newMapping->fOffset;
    mach_vm_size_t      _length   = newMapping->fLength;

    if( (!task) || (!fAddressMap) || (fAddressMap != get_task_map(task)))
        return( 0 );
    if( (fOptions ^ _options) & kIOMapReadOnly)
        return( 0 );
    if( (kIOMapDefaultCache != (_options & kIOMapCacheMask)) 
     && ((fOptions ^ _options) & kIOMapCacheMask))
        return( 0 );

    if( (0 == (_options & kIOMapAnywhere)) && (fAddress != toAddress))
        return( 0 );

    if( _offset < fOffset)
        return( 0 );

    _offset -= fOffset;

    if( (_offset + _length) > fLength)
        return( 0 );

    retain();
    if( (fLength == _length) && (!_offset))
    {
        newMapping = this;
    }
    else
    {
        newMapping->fSuperMap = this;
        newMapping->fOffset   = fOffset + _offset;
        newMapping->fAddress  = fAddress + _offset;
    }

    return( newMapping );
}

IOReturn IOMemoryMap::wireRange(
        uint32_t                options,
        mach_vm_size_t          offset,
        mach_vm_size_t          length)
{
    IOReturn kr;
    mach_vm_address_t start = trunc_page_64(fAddress + offset);
    mach_vm_address_t end   = round_page_64(fAddress + offset + length);
    
    if (kIODirectionOutIn & options)
    {
        kr = vm_map_wire(fAddressMap, start, end, (kIODirectionOutIn & options), FALSE);
    }
    else
    {
        kr = vm_map_unwire(fAddressMap, start, end, FALSE);
    }

    return (kr);
}


IOPhysicalAddress 
#ifdef __LP64__
IOMemoryMap::getPhysicalSegment( IOByteCount _offset, IOPhysicalLength * _length, IOOptionBits _options)
#else /* !__LP64__ */
IOMemoryMap::getPhysicalSegment( IOByteCount _offset, IOPhysicalLength * _length)
#endif /* !__LP64__ */
{
    IOPhysicalAddress   address;

    LOCK;
#ifdef __LP64__
    address = fMemory->getPhysicalSegment( fOffset + _offset, _length, _options );
#else /* !__LP64__ */
    address = fMemory->getPhysicalSegment( fOffset + _offset, _length );
#endif /* !__LP64__ */
    UNLOCK;

    return( address );
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#undef super
#define super OSObject

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

void IOMemoryDescriptor::initialize( void )
{
    if( 0 == gIOMemoryLock)
        gIOMemoryLock = IORecursiveLockAlloc();

    gIOLastPage = IOGetLastPageNumber();
}

void IOMemoryDescriptor::free( void )
{
    if( _mappings)
        _mappings->release();

    super::free();
}

IOMemoryMap * IOMemoryDescriptor::setMapping(
        task_t                  intoTask,
        IOVirtualAddress        mapAddress,
        IOOptionBits            options )
{
    return (createMappingInTask( intoTask, mapAddress,
                                    options | kIOMapStatic,
                                    0, getLength() ));
}

IOMemoryMap * IOMemoryDescriptor::map( 
        IOOptionBits            options )
{
    return (createMappingInTask( kernel_task, 0,
                                options | kIOMapAnywhere,
                                0, getLength() ));
}

#ifndef __LP64__
IOMemoryMap * IOMemoryDescriptor::map( 
        task_t                  intoTask,
        IOVirtualAddress        atAddress,
        IOOptionBits            options,
        IOByteCount             offset,
        IOByteCount             length )
{
    if ((!(kIOMapAnywhere & options)) && vm_map_is_64bit(get_task_map(intoTask)))
    {
        OSReportWithBacktrace("IOMemoryDescriptor::map() in 64b task, use ::createMappingInTask()");
        return (0);
    }

    return (createMappingInTask(intoTask, atAddress,
                                options, offset, length));
}
#endif /* !__LP64__ */

IOMemoryMap * IOMemoryDescriptor::createMappingInTask(
        task_t                  intoTask,
        mach_vm_address_t       atAddress,
        IOOptionBits            options,
        mach_vm_size_t          offset,
        mach_vm_size_t          length)
{
    IOMemoryMap * result;
    IOMemoryMap * mapping;

    if (0 == length)
        length = getLength();

    mapping = new IOMemoryMap;

    if( mapping
     && !mapping->init( intoTask, atAddress,
                        options, offset, length )) {
        mapping->release();
        mapping = 0;
    }

    if (mapping)
        result = makeMapping(this, intoTask, (IOVirtualAddress) mapping, options | kIOMap64Bit, 0, 0);
    else
        result = 0;

#if DEBUG
    if (!result)
        IOLog("createMappingInTask failed desc %p, addr %qx, options %x, offset %qx, length %llx\n",
                this, atAddress, (uint32_t) options, offset, length);
#endif

    return (result);
}

#ifndef __LP64__ // there is only a 64 bit version for LP64
IOReturn IOMemoryMap::redirect(IOMemoryDescriptor * newBackingMemory,
                                IOOptionBits         options,
                                IOByteCount          offset)
{
    return (redirect(newBackingMemory, options, (mach_vm_size_t)offset));
}
#endif

IOReturn IOMemoryMap::redirect(IOMemoryDescriptor * newBackingMemory,
                                IOOptionBits         options,
                                mach_vm_size_t       offset)
{
    IOReturn err = kIOReturnSuccess;
    IOMemoryDescriptor * physMem = 0;

    LOCK;

    if (fAddress && fAddressMap) do 
    {
        if (((fMemory->_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical)
            || ((fMemory->_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical64))
        {
            physMem = fMemory;
            physMem->retain();
        }

        if (!fRedirUPL)
        {
            vm_size_t size = round_page(fLength);
            int flags = UPL_COPYOUT_FROM | UPL_SET_INTERNAL 
                        | UPL_SET_LITE | UPL_SET_IO_WIRE | UPL_BLOCK_ACCESS;
            if (KERN_SUCCESS != memory_object_iopl_request((ipc_port_t) fMemory->_memEntry, 0, &size, &fRedirUPL,
                                            NULL, NULL,
                                            &flags))
                fRedirUPL = 0;

            if (physMem)
            {
                IOUnmapPages( fAddressMap, fAddress, fLength );
                if (false)
                    physMem->redirect(0, true);
            }
        }

        if (newBackingMemory)
        {
            if (newBackingMemory != fMemory)
            {
                fOffset = 0;
                if (this != newBackingMemory->makeMapping(newBackingMemory, fAddressTask, (IOVirtualAddress) this, 
                                                            options | kIOMapUnique | kIOMapReference | kIOMap64Bit,
                                                            offset, fLength))
                    err = kIOReturnError;
            }
            if (fRedirUPL)
            {
                upl_commit(fRedirUPL, NULL, 0);
                upl_deallocate(fRedirUPL);
                fRedirUPL = 0;
            }
            if (false && physMem)
                physMem->redirect(0, false);
        }
    }
    while (false);

    UNLOCK;

    if (physMem)
        physMem->release();

    return (err);
}

IOMemoryMap * IOMemoryDescriptor::makeMapping(
        IOMemoryDescriptor *    owner,
        task_t                  __intoTask,
        IOVirtualAddress        __address,
        IOOptionBits            options,
        IOByteCount             __offset,
        IOByteCount             __length )
{
#ifndef __LP64__
    if (!(kIOMap64Bit & options)) panic("IOMemoryDescriptor::makeMapping !64bit");
#endif /* !__LP64__ */

    IOMemoryDescriptor * mapDesc = 0;
    IOMemoryMap *        result = 0;
    OSIterator *         iter;

    IOMemoryMap *  mapping = (IOMemoryMap *) __address;
    mach_vm_size_t offset  = mapping->fOffset + __offset;
    mach_vm_size_t length  = mapping->fLength;

    mapping->fOffset = offset;

    LOCK;

    do
    {
        if (kIOMapStatic & options)
        {
            result = mapping;
            addMapping(mapping);
            mapping->setMemoryDescriptor(this, 0);
            continue;
        }

        if (kIOMapUnique & options)
        {
            addr64_t phys;
            IOByteCount       physLen;

//          if (owner != this)          continue;

            if (((_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical)
                || ((_flags & kIOMemoryTypeMask) == kIOMemoryTypePhysical64))
            {
                phys = getPhysicalSegment(offset, &physLen, kIOMemoryMapperNone);
                if (!phys || (physLen < length))
                    continue;
    
                mapDesc = IOMemoryDescriptor::withAddressRange(
                                phys, length, getDirection() | kIOMemoryMapperNone, NULL);
                if (!mapDesc)
                    continue;
                offset = 0;
                mapping->fOffset = offset;
            }
        }
        else
        {
            // look for a compatible existing mapping
            if( (iter = OSCollectionIterator::withCollection(_mappings)))
            {
                IOMemoryMap * lookMapping;
                while ((lookMapping = (IOMemoryMap *) iter->getNextObject()))
                {
                    if ((result = lookMapping->copyCompatible(mapping)))
                    {
                        addMapping(result);
                        result->setMemoryDescriptor(this, offset);
                        break;
                    }
                }
                iter->release();
            }
            if (result || (options & kIOMapReference))
            {
                if (result != mapping)
                {
                    mapping->release();
                    mapping = NULL;
                }
                continue;
            }
        }

        if (!mapDesc)
        {
            mapDesc = this;
            mapDesc->retain();
        }
        IOReturn
        kr = mapDesc->doMap( 0, (IOVirtualAddress *) &mapping, options, 0, 0 );
        if (kIOReturnSuccess == kr)
        {
            if (0 == (mapping->fOptions & kIOMapStatic)) {
            vm_map_iokit_mapped_region(mapping->fAddressMap, length);
        }

            result = mapping;
            mapDesc->addMapping(result);
            result->setMemoryDescriptor(mapDesc, offset);
        }
        else
        {
            mapping->release();
            mapping = NULL;
        }
    }
    while( false );

    UNLOCK;

    if (mapDesc)
        mapDesc->release();

    return (result);
}

void IOMemoryDescriptor::addMapping(
        IOMemoryMap * mapping )
{
    if( mapping)
    {
        if( 0 == _mappings)
            _mappings = OSSet::withCapacity(1);
        if( _mappings )
            _mappings->setObject( mapping );
    }
}

void IOMemoryDescriptor::removeMapping(
        IOMemoryMap * mapping )
{
    if( _mappings)
        _mappings->removeObject( mapping);
}

#ifndef __LP64__
// obsolete initializers
// - initWithOptions is the designated initializer 
bool
IOMemoryDescriptor::initWithAddress(void *      address,
                                    IOByteCount   length,
                                    IODirection direction)
{
    return( false );
}

bool
IOMemoryDescriptor::initWithAddress(IOVirtualAddress address,
                                    IOByteCount    length,
                                    IODirection  direction,
                                    task_t       task)
{
    return( false );
}

bool
IOMemoryDescriptor::initWithPhysicalAddress(
                                 IOPhysicalAddress      address,
                                 IOByteCount            length,
                                 IODirection            direction )
{
    return( false );
}

bool
IOMemoryDescriptor::initWithRanges(
                                        IOVirtualRange * ranges,
                                        UInt32           withCount,
                                        IODirection      direction,
                                        task_t           task,
                                        bool             asReference)
{
    return( false );
}

bool
IOMemoryDescriptor::initWithPhysicalRanges(     IOPhysicalRange * ranges,
                                                UInt32           withCount,
                                                IODirection      direction,
                                                bool             asReference)
{
    return( false );
}

void * IOMemoryDescriptor::getVirtualSegment(IOByteCount offset,
                                        IOByteCount * lengthOfSegment)
{
    return( 0 );
}
#endif /* !__LP64__ */

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

bool IOGeneralMemoryDescriptor::serialize(OSSerialize * s) const
{
    OSSymbol const *keys[2];
    OSObject *values[2];
    struct SerData {
        user_addr_t address;
        user_size_t length;
    } *vcopy;
    unsigned int index, nRanges;
    bool result;

    IOOptionBits type = _flags & kIOMemoryTypeMask;

    if (s == NULL) return false;
    if (s->previouslySerialized(this)) return true;

    // Pretend we are an array.
    if (!s->addXMLStartTag(this, "array")) return false;

    nRanges = _rangesCount;
    vcopy = (SerData *) IOMalloc(sizeof(SerData) * nRanges);
    if (vcopy == 0) return false;

    keys[0] = OSSymbol::withCString("address");
    keys[1] = OSSymbol::withCString("length");

    result = false;
    values[0] = values[1] = 0;

    // From this point on we can go to bail.

    // Copy the volatile data so we don't have to allocate memory
    // while the lock is held.
    LOCK;
    if (nRanges == _rangesCount) {
        Ranges vec = _ranges;
        for (index = 0; index < nRanges; index++) {
            user_addr_t addr; IOByteCount len;
            getAddrLenForInd(addr, len, type, vec, index);
            vcopy[index].address = addr;
            vcopy[index].length  = len;
        }
    } else {
        // The descriptor changed out from under us.  Give up.
        UNLOCK;
        result = false;
        goto bail;
    }
    UNLOCK;

    for (index = 0; index < nRanges; index++)
    {
        user_addr_t addr = vcopy[index].address;
        IOByteCount len = (IOByteCount) vcopy[index].length;
        values[0] =
            OSNumber::withNumber(addr, sizeof(addr) * 8);
        if (values[0] == 0) {
          result = false;
          goto bail;
        }
        values[1] = OSNumber::withNumber(len, sizeof(len) * 8);
        if (values[1] == 0) {
          result = false;
          goto bail;
        }
        OSDictionary *dict = OSDictionary::withObjects((const OSObject **)values, (const OSSymbol **)keys, 2);
        if (dict == 0) {
          result = false;
          goto bail;
        }
        values[0]->release();
        values[1]->release();
        values[0] = values[1] = 0;

        result = dict->serialize(s);
        dict->release();
        if (!result) {
          goto bail;
        }
    }
    result = s->addXMLEndTag("array");

 bail:
    if (values[0])
      values[0]->release();
    if (values[1])
      values[1]->release();
    if (keys[0])
      keys[0]->release();
    if (keys[1])
      keys[1]->release();
    if (vcopy)
        IOFree(vcopy, sizeof(SerData) * nRanges);
    return result;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 0);
#ifdef __LP64__
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 1);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 2);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 3);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 4);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 5);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 6);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 7);
#else /* !__LP64__ */
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 1);
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 2);
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 3);
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 4);
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 5);
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 6);
OSMetaClassDefineReservedUsed(IOMemoryDescriptor, 7);
#endif /* !__LP64__ */
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 8);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 9);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 10);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 11);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 12);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 13);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 14);
OSMetaClassDefineReservedUnused(IOMemoryDescriptor, 15);

/* ex-inline function implementation */
IOPhysicalAddress 
IOMemoryDescriptor::getPhysicalAddress()
        { return( getPhysicalSegment( 0, 0 )); }