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F_CTL (Frame Control)
8
This 3-byte (24-bit) field contains control information relating to the frame content as defined below.
Table 9:
Frame Control (F_CTL) bit definitions
Bit
Definition
Exchange context
23
Sequence context
22
First sequence
21
Last sequence
20
End of sequence
19
End connection
18
Chained sequence
17
Sequence initiative
16
X_ID reassigned
15
Invalid X_ID
14
Reserved
13
12
11
10
Retransmitted
9
sequence
Unidirectional
8
transmit
Continue sequence
7
condition
6
Abort sequence
5
condition
4
Relative offset
3
present
Reserved
2
Fill data bytes
1
0
Offset
8
This 4-byte field is used in data frames to define the relative offset (displacement) of the first byte of the payload from the
base address of the command. When the relative offset is present, bit 3 of F_CTL is set to indicate that relative offset is
valid.
The drive uses the SEQ_CNT value to verify that frames are being received in order. The drive does not use relative offset
in frames it receives. The drive sends relative offset information in data frames it originates.
Fibre Channel Interface Manual, Rev. D
Description
0 = Frame is from the exchange originator.
1 = Frame is from the exchange responder.
0 = Initiator
1 = Recipient
0 = Not the first sequence of the exchange.
1 = First sequence of the exchange.
0 = Not the last sequence of the exchange.
1 = Last sequence of the exchange.
0 = Not the last frame of the sequence.
1 = Last frame of the sequence.
Not supported.
Not supported.
0 = Hold sequence initiative.
1 = Transfer sequence initiative.
Not supported.
Not supported.
Not supported.
Not supported.
Not supported.
Not supported.
0 = Parameter field not meaningful.
1 = Parameter field equals relative offset.
End of data field fill bytes
00 = 0 bytes of fill.
01 = 1 byte of fill (last byte of data field).
02 = 2 bytes of fill (last 2 bytes of data field).
03 = 3 bytes of fill (last 3 bytes of data field).
25
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