
348
Registers
Chapter 4
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
8
31
OWN
This bit indicates whether the descriptor entry is owned by the host
(OWN = 0) or by the network controller (OWN = 1). The host sets the
OWN bit after it has emptied the buffer pointed to by the descriptor
entry. The network controller clears the OWN bit after
fi
lling the buffer
that the descriptor points to. Both the network controller and the host
must not alter a descriptor entry after it has relinquished ownership.
Error Summary
. ERR is the OR of FRAM, OFLO, CRC, and BUFF.
ERR is set by the network controller and cleared by the host.
Framing error
indicates that the incoming frame contains a non-integer
multiple of eight bits and there was an FCS error. If there was no FCS
error on the incoming frame, then FRAM is not set even if there was a
non-integer multiple of eight bits in the frame. FRAM is not valid in
internal loopback mode. FRAM is valid only when ENP is set and OFLO
is not. FRAM is set by the network controller and cleared by the host.
Over
fl
ow error
indicates that the receiver has lost all or part of the
incoming frame, due to an inability to move data from the receive FIFO
into a memory buffer before the internal FIFO over
fl
owed. OFLO is set
by the network controller and cleared by the host.
CRC indicates that the receiver has detected a CRC (FCS) error on the
incoming frame. CRC is valid only when ENP is set and OFLO is not.
CRC is set by the network controller and cleared by the host. CRC is
also set when the controller receives an RX_ER indication from the
external PHY through the MII.
Buffer Error
. If this bit is set, the end of this frame was lost because the
next descriptor was not available when it was needed. The
RcvMissPkts MIB counter is also incremented when this error occurs.
Start of Packet
indicates that this is the
fi
rst buffer used by the network
controller for this frame. If STP and ENP are both set to 1, the frame
fi
ts
into a single buffer. Otherwise, the frame is spread over more than one
buffer. STP is set by the controller and cleared by the host.
End of Packet
indicates that this is the last buffer used by the network
controller for this frame. It is used for data chaining buffers. If both STP
and ENP are set, the frame
fi
ts into one buffer and there is no data
chaining. ENP is set by the controller and cleared by the host.
Reserved
Physical Address Match
is set by the network controller when it
accepts the received frame due to a match of the frame's destination
address with the content of the physical address register. PAM is valid
only when ENP is set. PAM is set by the network controller and cleared
by the host.
8
30
ERR
8
29
FRAM
8
28
OFLO
8
27
CRC
8
26
BUFF
8
25
STP
8
24
ENP
8
8
23
22
PAM
Table 66.
Receive Descriptor Bit De
fi
nitions (Continued)
Offset
Bit
Name
Description