iokit/IOKit/IOMemoryDescriptor.h

150     @discussion The IOMemoryDescriptor object represents a buffer or range of memory, specified as one or more physical or virtual address ranges. It contains methods to return the memory's physically contiguous segments (fragments), for use with the IOMemoryCursor, and methods to map the memory into any address space with caching and placed mapping options. */
177     IOByteCount         _length;           /* length of all ranges */
334      static IOMemoryDescriptor * withRanges(IOVirtualRange * ranges,
348     @param task The task the virtual ranges are mapped into. Note that unlike IOMemoryDescriptor::withAddress(), kernel_task memory must be explicitly prepared when passed to this api. The task argument may be NULL to specify memory by physical address.
358     @abstract Create an IOMemoryDescriptor to describe one or more virtual ranges.
359     @discussion This method creates and initializes an IOMemoryDescriptor for memory consisting of an array of virtual memory ranges each mapped into a specified source task.  This memory descriptor needs to be prepared before it can be used to extract data from the memory described.
360     @param ranges An array of IOAddressRange structures which specify the virtual ranges in the specified map which make up the memory to be described. IOAddressRange is the 64bit version of IOVirtualRange.
361     @param rangeCount The member count of the ranges array.
364         kIOMemoryAsReference	For options:type = Virtual or Physical this indicate that the memory descriptor need not copy the ranges array into local memory.  This is an optimisation to try to minimise unnecessary allocations.
365     @param task The task each of the virtual ranges are mapped into. Note that unlike IOMemoryDescriptor::withAddress(), kernel_task memory must be explicitly prepared when passed to this api. The task argument may be NULL to specify memory by physical address.
369 					IOAddressRange * ranges,
385     @param task Only used options:type = Virtual, The task each of the virtual ranges are mapped into.
390         kIOMemoryAsReference	For options:type = Virtual or Physical this indicate that the memory descriptor need not copy the ranges array into local memory.  This is an optimisation to try to minimise unnecessary allocations.
406                                             IOPhysicalRange *	ranges,
441     virtual bool initWithRanges(IOVirtualRange * ranges,
446     virtual bool initWithPhysicalRanges(IOPhysicalRange * ranges,
460     @abstract Accessor to get the length of the memory descriptor (over all its ranges).
461     @discussion This method returns the total length of the memory described by the descriptor, ie. the sum of its ranges' lengths.
838     unsigned		_rangesCount;       /* number of address ranges in list */
843     task_t		_task;               /* task where all ranges are mapped to */
928     virtual bool initWithRanges(        IOVirtualRange * ranges,
934     virtual bool initWithPhysicalRanges(IOPhysicalRange * ranges,