Realtek RTL8169 Manual page 57

Offset# Bit#
0 31
0 30
0 29
0 28
0 27
0 26
0 25
0 24
0 23
0 22
0 21
0 20
0 19
0 18:17
0 16
0 15
0 14
0 13:0
4 31:17
cont...
2002/03/27
Symbol
OWN
Ownership: This bit, when set, indicates that the descriptor is owned by
the NIC. When cleared, it indicates that the descriptor is owned by the
host system. The NIC clears this bit when the NIC has filled up this Rx
buffer with a packet or part of a packet. In this case, OWN=0.
EOR End of Rx Descriptor Ring: This bit, set to 1, indicates that this
descriptor is the last descriptor of the Rx descriptor ring. Once the
NIC's internal receive descriptor pointer reaches here, it will return to
the first descriptor of the Rx descriptor ring after this descriptor is used
by packet reception.
FS First Segment descriptor: This bit, when set, indicates that this is the
first descriptor of a received packet, and this descriptor is pointing to the
first segment of the packet.
LS Last Segment Descriptor: This bit, when set, indicates that this is the last
descriptor of a received packet, and this descriptor is pointing to the last
segment of the packet.
MAR Multicast Address Packet Received: This bit, when set, indicates that
a multicast packet has been received.
PAM
Physical Address Matched: This bit, when set, indicates that the
destination address of this Rx packet matches the value in the
RTL8169's ID registers.
BAR
Broadcast Address Received: This bit, when set, indicates that a
broadcast packet has been received. BAR and MAR will not be set
simultaneously.
BOVF Buffer Overflow: This bit, when set, indicates that the receive buffer
has been exhausted before this packet was received.
FOVF FIFO Overflow: This bit, when set, indicates that a FIFO overflow has
occurred before this packet was received.
RWT
Receive Watchdog Timer Expired: This bit, when set, indicates that
the received packet length exceeded 4096 bytes.
RES Receive Error Summary: This bit, when set, indicates that at least one
of the following errors has occurred: CRC, RUNT, RWT, FAE. This bit
is valid only when LS (Last segment bit) is set
RUNT Runt Packet: This bit, when set, indicates that the received packet
length is smaller than 64 bytes. RUNT packets are able to be received
only when RCR_AR is set.
CRC CRC Error: This bit, when set, indicates that a CRC error has occurred
on the received packet. A CRC packet is able to be received only when
RCR_AER is set.
PID1, PID0 Protocol ID1, Protocol ID0: These 2 bits indicate the protocol type of
the packet received.
IPF
IP Checksum Failure: 1: Failure, 0: No failure.
UDPF UDP Checksum Failure: 1: Failure, 0: No failure.
TCPF TCP Checksum Failure: 1: Failure, 0: No failure.
Frame_Length When OWN=0 and LS =1, these bits indicate the received packet length
including CRC, in bytes.
RSVD Reserved
Description
PID1
Non-IP
TCP/IP
UDP/IP
IP
57
RTL8169
PID0
0 0
0 1
1 0
1 1
Rev.1.21