
350
Registers
Chapter 4
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
Figure 35.
Format of TFLAGS1 in Transmit Descriptor, Offset 00h
Table 67 on page 350 shows the transmit descriptor bit definitions.
Table 67.
Transmit Descriptor Bit De
fi
nitions
Offset
00h
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15-0
RES
BCNT[15:0]
OWN
ADD_FCS
LTINT
PRI_LOCK
STP
ENP
KILL
Offset
0
Bit
31
Name
OWN
Description
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
fi
lling the buffer pointed to by the descriptor entry. The
controller clears the OWN bit after transmitting the contents of the buffer.
Both the controller and the host must not alter a descriptor entry after it
has relinquished ownership.
Reserved location.
ADD_FCS dynamically controls the generation of FCS on a frame by
frame basis. This bit should be set with the ENP bit. However, for
backward compatibility, it is recommended that this bit be set for every
descriptor of the intended frame. When ADD_FCS is set, the state of
DXMTFCS is ignored and transmitter FCS generation is activated. When
ADD_FCS is cleared to 0, FCS generation is controlled by DXMTFCS.
When APAD_XMT (CMD2, bit 6) is set to 1, the setting of ADD_FCS has
no effect. ADD_FCS is set by the host, and is not changed by the
network controller.
Last Transmit Interrupt
. When enabled by the LTINTEN bit (CMD2, bit
9), LTINT is used to suppress interrupts after selected frames have been
copied to the transmit FIFO. When LTINT is cleared to 0 and ENP is set
to 1, the network controller does not set TINTx (INT0, bits 8-11) after the
corresponding frame has been copied to the transmit FIFO. TINTx is only
set when the last descriptor of a frame has both LTINT and ENP set to 1.
When LTINTEN is cleared to 0, the LTINT bit is ignored.
Reserved.
Priority Lock
. If PRI_LOCK is set on the
fi
rst descriptor of a frame
(when STP is set), the transmit ring arbitrator is forced to take the next
frame from the same ring as this one. If the
fi
rst descriptor of that frame
also has PRI_LOCK set, the process continues. When PRI_LOCK is not
set in the
fi
rst descriptor of a frame, the next frame comes from the ring
chosen by the arbiter. PRI_LOCK is ignored if STP is not set.
0
0
30
29
ADD_FCS
0
28
LTINT
0
0
27
26
PRI_LOCK