5–18
Chapter 5: IP Core Architecture
Avalon-MM Bridge TLPs
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
Figure 5–8
illustrates this Qsys system. (
Figure 5–8
uses a filter to hide the Conduit
interfaces that are not relevant in this discussion.)
Figure 5–9
illustrates the address map for this system.
The auto-assigned base addresses result in the following three large BARs:
■
BAR0 is 28 bits. This is the optimal size because it addresses the
Offchip_Data_Mem
which requires 28 address bits.
■
BAR2 is 29 bits. BAR2 addresses the
Quick_Data_Mem
which is 4 KBytes;. It
should only require 12 address bits; however, it is consuming 512 MBytes of
address space.
■
BAR4 is also 29 bits. BAR4 address
PCIe Cra
which is 16 KBytes. It should only
require 14 address bits; however, it is also consuming 512 MBytes of address space.
Figure 5–8. Qsys System for PCI Express with Poor Address Space Utilization
Figure 5–9. Poor Address Map