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docs: add zpci information to pci-addresses.rst

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Add some information on how pci address work on s390x.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
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Cornelia Huck 2020-04-15 12:51:51 +02:00 committed by Ján Tomko
parent e767f509b2
commit 53f687bbab
1 changed files with 64 additions and 0 deletions
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docs/pci-addresses.rst
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@ -184,3 +184,67 @@ 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