Hi,
+Plug only legacy PCI devices as Root Complex Integrated Devices
+even if the PCIe spec does not forbid PCIe devices.
I suggest "even though the PCI Express spec does not forbid PCI Express
devices as Integrated Devices". (Detail is good!)
While talking about integrated devices: There is docs/q35-chipset.cfg,
which documents how to mimic q35 with integrated devices as close and
complete as possible.
Usage:
qemu-system-x86_64 -M q35 -readconfig docs/q35-chipset.cfg $args
Side note for usb: In practice you don't want to use the tons of
uhci/ehci controllers present in the original q35 but plug xhci into one
of the pcie root ports instead (unless your guest doesn't support xhci).