Intel Extensible Firmware Interface - Manual (Page 911)

32/64-Bit UNDI Specification
Version 1.10 12/01/02 E-45
// UNDI will read or write the device io space using this
// call-back function. It passes the number of bytes as the
// len parameter and it will be either 1,2,4 or 8.
//
// This field cannot be set to zero.
//
PXE_UINT64 Mem_IO;
//
// PXE_VOID Map_Mem(UINT64 unq_id, UINT64 virtual_addr,
// UINT32 size, UINT32 Direction, UINT64 mapped_addr);
//
// UNDI will pass the virtual address of a buffer, direction of
// the data flow from/to the mapped buffer (the constants
// values for the direction flag are defined below)
// and a place holder (pointer) for the mapped address.
// This call will Map the given address to a physical DMA
// address and write the result to the mapped_addr pointer. If
// there is no need to map the given address to a lower
// physical address i.e. the given virtual address points to a
// physical memory that can be used for the DMA read/write, it
// converts the given virtual address to its physical address
// and write that in the mapped address pointer.
//
// This field can be set to zero if there is no mapping service
// available or if all the physical addresses are DMA
// compatible.
//
UINT64 Map_Mem;
//
// PXE_VOID UnMap_Mem(UINT64 unq_id, UINT64 virtual_addr,
// UINT32 size, UINT32 Direction, UINT64 mapped_addr);
//
// UNDI will pass the virtual and mapped addresses of a buffer
// This call will un map the given address
//
// This field can be set to zero if there is no unmapping
// service available
//
UINT64 UnMap_Mem;