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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. device on the host.
Of course, all the rules and behaviors described above still apply. 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