1 files changed, 15 insertions, 0 deletions
diff --git a/hw/pci_internals.h b/hw/pci_internals.h
index 71c8b51fd0..96690b72d3 100644
--- a/hw/pci_internals.h
+++ b/hw/pci_internals.h
@@ -41,6 +41,21 @@ struct PCIBridge {
 
     /* private member */
     PCIBus sec_bus;
+    /*
+     * Memory regions for the bridge's address spaces.  These regions are not
+     * directly added to system_memory/system_io or its descendants.
+     * Bridge's secondary bus points to these, so that devices
+     * under the bridge see these regions as its address spaces.
+     * The regions are as large as the entire address space -
+     * they don't take into account any windows.
+     */
+    MemoryRegion address_space_mem;
+    MemoryRegion address_space_io;
+    /*
+     * Aliases for each of the address space windows that the bridge
+     * can forward. Mapped into the bridge's parent's address space,
+     * as subregions.
+     */
     MemoryRegion alias_pref_mem;
     MemoryRegion alias_mem;
     MemoryRegion alias_io;