Altera IP Compiler for PCI Express - Manual (Page 52)

3–16 Chapter 3: Parameter Settings
IP Core Parameters
IP Compiler for PCI Express User Guide August 2014 Altera Corporation
Buffer Setup
The Buffer Setup page contains the parameters for the receive and retry buffers.
Table 3–12 describes the parameters you can set on this page.
The IP Compiler for PCI Express parameter editor that appears in the Qsys flow
provides only the Maximum payload size and RX buffer credit allocation –
performance for received requests
buffer setup parameters. This parameter editor
also displays the read-only RX buffer space allocation information without the space
usage or totals information. For more information, refer to
“Parameters in the Qsys
Design Flow” on page 3–1 .
MSI-X Table size
0x068 [26:16]
10:0
System software reads this field to determine the MSI-X Table size <N>, which is
encoded as <N–1>. For example, a returned value of 10’b00000000011 indicates a
table size of 4. This field is read-only.
MSI-X Table
Offset
31:3
Points to the base of the MSI-X Table. The lower 3 bits of the table BAR indicator
(BIR) are set to zero by software to form a 32-bit qword-aligned offset. This field is
read-only.
MSI-X Table BAR
Indicator
<5–1>:0
Indicates which one of a function’s Base Address registers, located beginning at
0x10 in configuration space, is used to map the MSI-X table into memory space.
This field is read-only.
Pending Bit Array (PBA)
Offset
31:3
Used as an offset from the address contained in one of the function’s Base Address
registers to point to the base of the MSI-X PBA. The lower 3 bits of the PBA BIR are
set to zero by software to form a 32-bit qword-aligned offset. This field is read-only.
BAR Indicator
(BIR)
<5–1>:0
Indicates which of a function’s Base Address registers, located beginning at 0x10 in
configuration space, is used to map the function’s MSI-X PBA into memory space.
This field is read-only.
Note to Table 3–11 :
(1) Throughout The PCI Express User Guide, the terms word, dword and qword have the same meaning that they have in the PCI Express Base
Specification Revision 1.0a , 1.1 , or 2.0 . A word is 16 bits, a dword is 32 bits, and a qword is 64 bits.
Table 3–11. Capabilities Parameters (Part 4 of 4)
Parameter Value Description
Table 3–12. Buffer Setup Parameters (Part 1 of 3)
Parameter Value Description
Maximum
payload size
0x084
128 bytes,
256 bytes,
512 bytes,
1 KByte,
2 KBytes
Specifies the maximum payload size supported. This parameter sets the read-only
value of the max payload size supported field of the device capabilities register
(0x084[2:0]) and optimizes the IP core for this size payload.
Number of
virtual channels
0x104
1–2
Specifies the number of virtual channels supported. This parameter sets the
read-only extended virtual channel count field of port virtual channel capability
register 1 and controls how many virtual channel transaction layer interfaces are
implemented. The number of virtual channels supported depends upon the
configuration, as follows:
Hard IP: 1–2 channels for Stratix IV GX devices, 1 channel for Arria II GX,
Arria II GZ, Cyclone IV GX, and HardCopy IV GX devices
Soft IP: 2 channels
Qsys: 1 channel