SRIOV VF BARs Tab - 1.0 English

Versal ACAP DMA and Bridge Subsystem for PCI Express Product Guide (PG344)
Document ID
PG344
Release Date
2022-05-20
Version
1.0 English

The SRIOV VF BARs tab is shown in the following figure.

Figure 1. SRIOV VF BARs Tab

The SRIOV VF BARs tab enables you to configure the base address registers (BARs) for all virtual function (VFs) within a virtual function group (VFG). All the VFs within the same VFG share the same BASE ADDRESS Registers (BARS) configurations. Each Virtual Function supports up to six 32-bit BARs or three 64-bit BARs. Virtual Function BARs can be configured without any dependency on the settings of the associated Physical Functions BARs.

Important: The DMA requires a large amount of space to support functions and queues. By default, 64-bit BAR space is selected for the DMA BAR. This applies for PF and VF bars. You must calculate your design needs first before selecting between 64-bit and 32-bit BAR space.

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.

BAR
Select applicable BARs using the checkboxes.
Type
Select the relevant option:
DMA
Is fixed to BAR0 space.
AXI Lite Master
Is fixed to BAR1 space.
AXI Bridge Master
Is fixed to BAR2 space.
For all other bars, select either AXI Lite Master or AXI Bridge Master.
Note: The current IP supports a maximum of one DMA BAR (or a management BAR given only mailbox is required) for one VF. The other BARs can be configured as AXI Lite Master to access the assigned memory space through the AXI4-Lite bus. Virtual Function BARs do not support I/O space and must be configured to map to the appropriate memory space.
64-bit
VF BARs can be either 64-bit or 32-bit. The default is 64-bit BAR.
  • 64-bit addressing is supported for the DMA BAR.
  • 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 32-bit or 64-bit BAR selected.
The Supported Page Sizes field indicates all the page sizes supported by the PF and, as required by the SR-IOV specification. Based on the Supported Page Size field, the system software sets the System Page Size field which is used to map the VF BAR memory addresses. Each VF BAR address is aligned to the system page boundary.
By default, DMA space is 32 Kbytes. With this much space allocated, the user logic can access 256 queues for a VF function.
Value
The value assigned to the BAR based on the current selections.