[libvirt PATCH 4/4] docs: Remove one example from pci-addresses.rst

Boris Fiuczynski fiuczy at linux.ibm.com
Thu Apr 16 10:29:06 UTC 2020

On 4/15/20 7:47 PM, Cornelia Huck wrote:
> On Wed, 15 Apr 2020 19:31:36 +0200
> Andrea Bolognani <abologna at redhat.com> wrote:
>> The idea behind this document is to show, with actual examples,
>> that users should not expect PCI addresses in the domain XML and
>> in the guest OS to match.
>> The first zPCI example already serves this purpose perfectly, so
>> in the interest of keeping the page as brief and easy to digest
>> as possible the second one is removed.
>> Signed-off-by: Andrea Bolognani <abologna at redhat.com>
>> ---
>>   docs/pci-addresses.rst | 19 -------------------
>>   1 file changed, 19 deletions(-)
>> diff --git a/docs/pci-addresses.rst b/docs/pci-addresses.rst
>> index 86a41df6ce..1d2dc8e5fc 100644
>> --- a/docs/pci-addresses.rst
>> +++ b/docs/pci-addresses.rst
>> @@ -204,25 +204,6 @@ 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'>
>> -    <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
>> -
I suggest to use the zpci addressing from the removed example because it 
outlines more clearly the differences in the parameters.
Something like the example below:

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' 
     <zpci uid='0x0001' fid='0x00000000'/>
<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' 
     <zpci uid='0x0007' fid='0x00000003'/>

will result in the following in a Linux guest:

0007:00:00.0 Ethernet controller: Red Hat, Inc. Virtio network device

The slot for the PCI device in the guest OS is defined by the fid 
(function id).

>>   Device assignment
>>   =================
> Hm, should that rather go somewhere else? What I wanted to show is "you
> can have the same PCI address in the XML and still get a different PCI
> address in the guest, if you change the zpci values", as that might be
> another source of confusion.

Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

More information about the libvir-list mailing list