The PCIe BARs tab is shown in the following figure.
- 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. 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 DMA, AXI Lite Master or AXI Bridge Master.
- 64-bit BARs
- The address space can be as small as 128 bytes or as large as 8 Exabytes. Used for DMA, AXI Lite Master or AXI Bridge Master.
All BAR register share these options.
BAR selections are configurable. By default DMA is at BAR 0 (64 bit), AXI-Lite Master is at BAR 2 (64 bit). These selections can be changed according to user needs.
- Click the checkbox to enable the BAR. Deselect the checkbox to disable the BAR.
- Select from DMA (by
default in BAR0), AXI Lite Master (by
default in BAR1, if enabled), or AXI Bridge
Master (by default in BAR2, if enabled). All other BARs, you
can select between AXI List Master and AXI Bridge Master. Expansion ROM can
be enabled by selecting BAR6
For 64-bit BAR (default selection), DMA (by default in BAR0), AXI Lite Master (by default in BAR2, if enabled), and AXI Bridge Master (by default in BAR4, if enabled). Expansion ROM can be enabled by selection BAR6.
- DMA by default is assigned to BAR0 space and for all PFs. DMA option can be selected in any available BAR (only one BAR can have DMA option). If you select DMA Mailbox Management rather than DMA; however, DMA Mailbox Management will not allow you to perform any DMA operations. After selecting the DMA Mailbox Management option, the host has access to the extended Mailbox space. For details about this space, see the QDMA_PF_MAILBOX (0x22400) register space.
- AXI Lite Master
- Select the AXI Lite Master interface option for any BAR space. The Size, scale and address translation are configurable.
- AXI Bridge Master
- Select the AXI Bridge Master interface option for any BAR space. The Size, scale and address translation are configurable.
- Expansion ROM
- When enabled, this space is accessible on the AXI4-Lite Master. This is a read-only space. The size, scale, and address translation are configurable.
- The available Size range depends on the 32-bit or 64-bit bar selected. The DMA requires 256 Kbytes of space, which is the fixed default selection. Other BAR size selections are available, but must be specified.
- Select between Byte, Kilobytes and Megabytes.
- The value assigned to the BAR based on the current selections.