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Table 7: Sideband Signal Descriptions in pcie(n)_m_axis_cq_tuser (cont'd)
Bit Index
Name
Width
Description
39:8
byte_en[31:0]
32
The user logic can optionally use these byte enable bits to
determine the valid bytes in the payload of a packet being
transferred. The assertion of bit i of this bus during a
transfer indicates that byte i of the pcie(n)_m_axis_cq_tdata
bus contains a valid payload byte. This bit is not asserted for
descriptor bytes.
Although the byte enables can be generated by user logic
from information in the request descriptor (address and
length) as well as the settings of the first_be and last_be
signals, you can use these signals directly instead of
generating them from other interface signals.
When the payload size is more than two Dwords (eight
bytes), the one bit on this bus for the payload is always
contiguous. When the payload size is two Dwords or less,
the one bit can be non-contiguous.
For the special case of a zero-length memory write
transaction defined by the PCI Express specifications, the
byte_en bits are all 0s when the associated one-DW payload
is being transferred.
Bits [31:16] of this bus are set permanently to 0 by the core
when the interface width is configured as 128 bits, and bits
[31:8] are set permanently to 0 when the interface width is
configured as 64 bits.
40
sop
1
Start of packet.
This signal is asserted by the core in the first beat of a
packet to indicate the start of the packet. Using this signal is
optional.
41
discontinue
1
This signal is asserted by the core in the last beat of a TLP, if
it has detected an uncorrectable error while reading the TLP
payload from its internal FIFO memory. The user application
must discard the entire TLP when such an error is signaled
by the core.
This signal is never asserted when the TLP has no payload.
It is asserted only in a cycle when pcie(n)_m_axis_cq_tlast is
High.
When the core is configured as an Endpoint, the error is also
reported by the core to the Root Complex to which it is
attached, using Advanced Error Reporting (AER).
84:53
parity
32
Bit i provides the odd parity computed for byte i of
pcie(n)_m_axis_cq_tdata. Only the lower 16 bits are used
when the interface width is 128 bits, and only the lower 8
bits are used when the interface width is 64 bits. Bits [31:16]
are set permanently to 0 by the core when the interface
width is configured as 128 bits, and bits [31:8] are set
permanently to 0 when the interface width is configured as
64 bits.
85
PASID TLP Valid
1
Indicates PASID TLP is valid.
105:86
PASID
20
Indicates PASID TLP prefix.
106
Execute Requested
1
Indicates Execute Requested to the user design.
107
Privileged Mode Requested
1
Indicates Privileged Mode Requested to the user design.
Chapter 3: Product Specification
PG346 (v3.3) November 16, 2022
CPM Mode for PCI Express
44