Intel Extensible Firmware Interface, Specification

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Extensible Firmware Interface Specification
464 12/12/00 Version 1.02
G.4.19 Receive
When the network adapter has received a frame, this command is used to copy the frame into
driver/application storage. Once a frame has been copied, it is removed from the receive queue.
G.4.19.1 Issuing the Command
To issue a Receive command, create a CDB and fill it in as shows in the table below:
CDB Field How to initialize the CDB structure for a Receive command
OpCode PXE_OPCODE_RECEIVE
OpFlags Set as needed.
CPBsize sizeof(PXE_CPB_RECEIVE)
DBsize sizeof(PXE_DB_RECEIVE)
CPBaddr
Address of a
PXE_CPB_RECEIVE
structure.
DBaddr
Address of a
PXE_DB_RECEIVE
structure.
StatCode PXE_STATCODE_INITIALIZE
StatFlags PXE_STATFLAGS_INITIALIZE
IFnum
A valid interface number from zero to
!PXE.IFcnt
.
Control Set as needed.
Preparing the CPB
If multiple frames per command are supported (see
!PXE.Implementation
flags), multiple
CPBs can be packed together. For each complete received frame, a receive buffer large enough to
contain the entire unfragmented frame needs to be described in the CPB.
#pragma pack(1)
typedef struct s_pxe_cpb_receive {
// Address of first byte of receive buffer. This is also the
// first byte of the frame header.
PXE_UINT64 BufferAddr;
// Length of receive buffer. This must be large enough to hold
// the received frame (media data). If the length of
// smaller than the received frame, data will be lost.
PXE_UINT32 BufferLen;
// Reserved, must be set to zero.
PXE_UINT32 reserved;
} PXE_CPB_RECEIVE;
#pragma pack()