3.1.2.2
Desc_cmd_base
This descriptor defines the command parameters that are common to all types of
commands. The Desc_cmd_base format is 8 bytes for either 32-bit or 64-bit addressing
modes.
Reserved
Packet_Size[8:0]
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
Reserved
Reserved
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Field Name
Reserved
Bits
Default Description
63:41
0
Reserved
Packet_size[8:0]
Packet Size.
This field is only valid when Command Structure
Mode, CSM, is set to small packet mode.
The packet size will vary with the command
addressing mode (32 or 64-bit addressing) and the
size of the information field (see Section 3.1.3.5).
This field indicates the real source data size, not
including the information and descriptor fields. Note,
for small packet mode, the total command size must
be less than or equal to 512 bytes.
The packet size range in bytes is:
1 - maximum_packet_size
where
40:32
0
Maximum_packet_size = 512 - (info field) -
(descriptor field)
| Total cmd structure size must be <= 512 bytes |
Info field
Desc field
Source data
|
packet_size[8:0]
|
820x – Data Sheet, DS-0157-D
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