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Hand-entering indexes for 20 PCI controllers is not as tedious as manually determining and entering their PCI addresses, but it's still annoying, and the algorithm for determining the proper index is incredibly simple (in all cases except one) - just pick the lowest unused index. The one exception is USB2 controllers because multiple controllers in the same group have the same index. For these we look to see if 1) the most recently added USB controller is also a USB2 controller, and 2) the group *that* controller belongs to doesn't yet have a controller of the exact model we're just now adding - if both are true, the new controller gets the same index, but in all other cases we just assign the lowest unused index. With this patch in place and combined with the automatic PCI address assignment, we can define a PCIe switch with several ports like this: <controller type='pci' model='pcie-root-port'/> <controller type='pci' model='pcie-switch-upstream-port'/> <controller type='pci' model='pcie-switch-downstream-port'/> <controller type='pci' model='pcie-switch-downstream-port'/> <controller type='pci' model='pcie-switch-downstream-port'/> <controller type='pci' model='pcie-switch-downstream-port'/> <controller type='pci' model='pcie-switch-downstream-port'/> ... These will each get a unique index, and PCI addresses that connect them together appropriately with no pesky numbers required.
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>