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PXB is a "light-weight" host bridge whose purpose is to enable the main host bridge to support multiple PCI root buses for pc machines. As oposed to PCI-2-PCI bridge's secondary bus, PXB's bus is a primary bus and can be associated with a NUMA node (different from the main host bridge) allowing the guest OS to recognize the proximity of a pass-through device to other resources as RAM and CPUs. The PXB is composed from: - A primary PCI bus (can be associated with a NUMA node) Acts like a normal pci bus and from the functionality point of view is an "expansion" of the bus behind the main host bridge. - A pci-2-pci bridge behind the primary PCI bus where the actual devices will be attached. - A host-bridge PCI device Situated on the bus behind the main host bridge, allows the BIOS to configure the bus number and IO/mem resources. It does not have its own config/data register for configuration cycles, this being handled by the main host bridge. - A host-bridge sysbus to comply with QEMU current design. Signed-off-by: Marcel Apfelbaum <marcel@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Laszlo Ersek <lersek@redhat.com>
Read the documentation in qemu-doc.html or on http://wiki.qemu-project.org - QEMU team