Re: [libvirt PATCH 4/4] docs: Remove one example from pci-addresses.rst
On 4/15/20 7:47 PM, Cornelia Huck wrote:
On Wed, 15 Apr 2020 19:31:36 +0200
Andrea Bolognani <abologna(a)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(a)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'
function='0x0'>
<zpci uid='0x0001' fid='0x00000000'/>
</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='0x0007' fid='0x00000003'/>
</address>
</interface>
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
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