L-Tile and H-Tile Avalon® Memory-mapped+ Intel® FPGA IP for PCI Express* User Guide

ID 683527
Date 3/05/2024
Public
Document Table of Contents

4.2. Base Address Registers

Table 37.  BAR Registers

Parameter

Value

Description

BAR0 Type

Disabled

64-bit prefetchable memory

32-bit non-prefetchable memory

If you select 64-bit prefetchable memory, 2 contiguous BARs are combined to form a 64-bit prefetchable BAR; you must set the higher numbered BAR to Disabled. A non-prefetchable 64‑bit BAR is not supported because in a typical system, the maximum non-prefetchable memory window is 32 bits.

Defining memory as prefetchable allows contiguous data to be fetched ahead. Prefetching memory is advantageous when the requestor may require more data from the same region than was originally requested. If you specify that a memory is prefetchable, it must have the following 2 attributes:

  • Reads do not have side effects such as changing the value of the data read
  • Write merging is allowed
BAR1 Size

256 Bytes – 8 EBytes

Specifies the size of the address space accessible to the BAR.

BAR2 Size

256 Bytes – 8 EBytes

Specifies the size of the address space accessible to the BAR.

BAR3 Size

256 Bytes – 8 EBytes

Specifies the size of the address space accessible to the BAR.

BAR4 Size

256 Bytes – 8 EBytes

Specifies the size of the address space accessible to the BAR.

BAR5 Size

256 Bytes – 8 EBytes

Specifies the size of the address space accessible to the BAR.

BAR1 Type

Disabled

32-bit non-prefetchable memory

 

BAR2 Type

Disabled

64-bit prefetchable memory

32-bit non-prefetchable memory

 

BAR3 Type

Disabled

32-bit non-prefetchable memory

 

BAR4 Type

Disabled

64-bit prefetchable memory

32-bit non-prefetchable memory

 

BAR5 Type

Disabled

32-bit non-prefetchable memory