Maximum Request Size - 4.4 English - PG156

UltraScale Devices Gen3 Integrated Block for PCI Express LogiCORE IP Product Guide (PG156)
Document ID
PG156
Release Date
2024-12-06
Version
4.4 English

A Memory Read cannot request more than the value stated in Max_Request_Size, which is given by Configuration bits cfg_dcommand[14:12] as defined in the following table. If the user application does not read the Max_Request_Size value, it must use the default value of 128 bytes.

Table 1. Max_Request_Size Settings
cfg_dcommand[14:12] Max_Request_Size
Bytes DW QW Credits
000b 128 32 16 8
001b 256 64 32 16
010b 512 128 64 32
011b 1024 256 128 64
100b 2048 512 256 128
101b 4096 1024 512 256
110b–111b Reserved