qemu/docs/pcie.txt

7 devices in PCI Express based machines and explains the reasoning behind
34 PCI Express devices should be plugged only into PCI Express Root Ports and
39 Place only the following kinds of devices directly on the Root Complex:
41         not controllers. Place only legacy PCI devices on
45         Although the PCI Express spec does not forbid PCI Express devices as
47         devices with the Root Complex. Guest OSes are suspected to behave
48         strangely when PCI Express devices are integrated
81 A PCI Express Root bus supports up to 32 devices. Since each
86 Prefer grouping PCI Express Root Ports into multi-function devices
92 Plug only PCI Express devices into PCI Express Ports.
135 Legacy PCI devices can be plugged into pcie.0 as Integrated Endpoints,
143 (each supporting also 32 slots) will support hundreds of legacy devices.
186 fragmented by fixed IO ports owned by platform devices resulting in at most
188 if devices with IO BARs are used in the PCI Express hierarchy. Using the
190 PCI Express devices within PCI Express hierarchy.
192 The PCI Express spec requires that PCI Express devices work properly
207 devices to prevent bus number starvation.
213 The bus_nr properties of the pxb-pcie devices partition the 0..255 bus
217 that the command line sets for other pxb-pcie devices.
222 The PCI Express root buses (pcie.0 and the buses exposed by pxb-pcie devices)
223 do not support hot-plug, so any devices plugged into Root Complexes
233 PCI devices can be hot-plugged into PCI Express to PCI and PCI-PCI Bridges.
238 PCI Express devices can be natively hot-plugged/hot-unplugged into/from
247         4K IO space and 2M MMIO range to be used for all devices behind it.
272 Host devices are mostly PCI Express and should be plugged only into
274 PCI-PCI Bridge slots can be used for legacy PCI host devices.
296 7. Virtio devices
298 Virtio devices plugged into the PCI hierarchy or as Integrated Endpoints
300 Transitional virtio devices work in both IO and MMIO modes depending on
302 to transitional virtio devices.
304 Virtio devices plugged into PCI Express ports are PCI Express devices and
310 legacy behavior) for PCI Express virtio devices causing them to