Figure 61: PF BARs Tab Showing PF0
• Base Address Register Overview: In Endpoint configuration, the core supports up to six 32-bit
BARs or three 64-bit BARs, and the Expansion read-only memory (ROM) BAR. In Root Port
configuration, the core supports up to two 32-bit BARs or one 64-bit BAR, and the Expansion
ROM BAR. BARs can be one of two sizes:
• 32-bit BARs: The address space can be as small as 128 bytes or as large as 2 gigabytes.
Used for Memory or I/O.
• 64-bit BARs: The address space can be as small as 128 bytes or as large as 8 Exabytes.
Used for Memory only.
All BAR registers share these options:
• Checkbox: Click the checkbox to enable the BAR; deselect the checkbox to disable the
BAR.
• Type: Bars can either be I/O or Memory.
• I/O: I/O BARs can only be 32-bit; the Prefetchable option does not apply to I/O BARs.
I/O BARs are only enabled for a Legacy PCI Express Endpoint.
• Memory: Memory BARs can be either 64-bit or 32-bit and can be prefetchable. When a
BAR is set as 64 bits, it uses the next BAR for the extended address space and makes
the next BAR inaccessible.
• Size: The available Size range depends on the PCIe Device/Port Type and the Type of BAR
selected. The following table lists the available BAR size ranges.
Chapter 5: Design Flow Steps
PG346 (v3.3) November 16, 2022
CPM Mode for PCI Express
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