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This section defines some types and values that are fundamental to memory management for native drivers.
Values of type LogicalAddress represent a location in an address space:
typedef void *LogicalAddress;
Values of type PhysicalAddress represent location in physical memory. They are used primarily with DMA I/O operations:
typedef void *PhysicalAddress;
A LogicalAddressRange structure is a description of a single logically addressed buffer:
struct LogicalAddressRange
{
LogicalAddress address;
ByteCount count;
};
typedef struct LogicalAddressRange LogicalAddressRange;
typedef struct LogicalAddressRange *LogicalAddressRangePtr;
A PhysicalAddressRange structure is a description of a single physically addressed buffer:
struct PhysicalAddressRange
{
PhysicalAddress address;
ByteCount count;
};
typedef struct PhysicalAddressRange PhysicalAddressRange;
typedef struct PhysicalAddressRange *PhysicalAddressRangePtr;
An AddressRange structure is a description of a single buffer, in which the buffer address may be either logical or physical:
struct AddressRange
{
void *base;
ByteCount length;
};
typedef struct AddressRange AddressRange;
Address spaces are referred to by values of type AddressSpaceID. The value kCurrentAddressSpaceID refers to the current address space:
typedef KernelID AddressSpaceID;
enum
{
kCurrentAddressSpaceID = 0
};