---
title: PG_PCI_BAR_MMIO
framework: Paravirtualized Graphics
role: symbol
role_heading: Global Variable
platforms: [Mac Catalyst 14.0+, macOS 11.0+]
path: paravirtualizedgraphics/pg_pci_bar_mmio
---

# PG_PCI_BAR_MMIO

The base address register to use when advertising the graphics stack inside a virtual machine.

## Declaration

```swift
var PG_PCI_BAR_MMIO: Int32 { get }
```

## Discussion

Discussion Specify the following characteristics for the memory that this base address register references: Allocate 16 kilobytes of memory. Place MSI interrupt vectors between offsets 0x0000 and 0x0FFF of this memory block. Place MMIO mapped registers starting at offset 0x1000. When you see a read or write access to this memory region, call mmioRead(atOffset:) or mmioWrite(atOffset:value:) on the host device. The framework aligns reads and writes to addresses that are multiples of 4 bytes with a length of 4 bytes.

## See Also

### PCI Device Characteristics

- [PG_PCI_DEVICE_ID](paravirtualizedgraphics/pg_pci_device_id.md)
- [PG_PCI_VENDOR_ID](paravirtualizedgraphics/pg_pci_vendor_id.md)
- [PG_PCI_MAX_MSI_VECTORS](paravirtualizedgraphics/pg_pci_max_msi_vectors.md)
- [PGCopyOptionROMURL()](paravirtualizedgraphics/pgcopyoptionromurl().md)