Re: [PATCH] docs: add zpci information to pci-addresses.rst

Add some information on how pci address work on s390x. Signed-off-by: Cornelia Huck <cohuck(a)redhat.com&gt;

--- docs/pci-addresses.rst | 63 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) diff --git a/docs/pci-addresses.rst b/docs/pci-addresses.rst index 923783a151b0..9e241a24fcfb 100644 --- a/docs/pci-addresses.rst +++ b/docs/pci-addresses.rst @@ -184,3 +184,66 @@ guest OS rather than as ``0001:08:00.1``, which is the address of the device on the host. Of course, all the rules and behaviors described above still apply. + +zPCI addresses +============== + +For s390x machines, PCI addresses are handled yet differently. No +topology information is relayed in the PCI addresses; instead, the +``fid`` and ``uid`` elements of the ``zpci`` device convey information.

+In the simplest case, the following XML snippet + +:: + + <controller type='pci' index='0' model='pci-root'/> + <controller type='pci' index='1' model='pci-bridge'> + <model name='pci-bridge'/> + <target chassisNr='1'/> + <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'> + <zpci uid='0x0002' fid='0x00000001'/> + </address> + </controller> + <interface type='bridge'> + <mac address='02:ca:fe:fa:ce:04'/> + <source bridge='virbr0'/> + <model type='virtio'/> + <address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'> + <zpci uid='0x0001' fid='0x00000000'/> + </address> + </interface> + +will result in the following in a Linux guest:: + + 0001:00:00.0 Ethernet controller: Red Hat, Inc. Virtio network device + +Note that the PCI bridge is not visible in the guest; s390x always has a flat +topology. + +Neither are any changes in the PCI address visible in the guest; replacing +the PCI address for the virtio-net device with + +:: + + <address type='pci' domain='0x0000' bus='0x01' slot='0x07' function='0x3'> + +will result in the exactly same view in the guest, as the addresses there +are generated from the information provided via the ``zpci`` element (in +fact, from the ``uid``). +

+Therefore, replacing the virtio-net device definition with the following XML +snippet + +:: + + <interface type='bridge'> + <mac address='02:ca:fe:fa:ce:04'/> + <source bridge='virbr0'/> + <model type='virtio'/> + <address type='pci' domain='0x0000' bus='0x01' slot='0x07' function='0x3'> + <zpci uid='0x0007' fid='0x00000003'/> + </address> + </interface> + +will yield the following result in a Linux guest:: + + 0007:00:00.0 Ethernet controller: Red Hat, Inc. Virtio network device