[PATCH 2/2] docs: Improve zPCI section in pci-addresses.rst

[Cornelia Huck]

On Fri, 17 Apr 2020 10:50:02 +0200
Boris Fiuczynski <fiuczy at linux.ibm.com> wrote:

> On 4/16/20 6:14 PM, Cornelia Huck wrote:
> > On Thu, 16 Apr 2020 17:56:18 +0200
> > Boris Fiuczynski <fiuczy at linux.ibm.com> wrote:
> >   
> >> Improving the zPCI example by choosing more distinct values and
> >> adding explanation for fid.
> >>
> >> Signed-off-by: Boris Fiuczynski <fiuczy at linux.ibm.com>
> >> ---
> >>   docs/pci-addresses.rst | 15 ++++++++-------
> >>   1 file changed, 8 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/docs/pci-addresses.rst b/docs/pci-addresses.rst
> >> index 7c8e9edd73..4492389da5 100644
> >> --- a/docs/pci-addresses.rst
> >> +++ b/docs/pci-addresses.rst
> >> @@ -176,14 +176,14 @@ In the simplest case, the following XML snippet
> >>       <model name='pci-bridge'/>
> >>       <target chassisNr='1'/>
> >>       <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'>
> >> -      <zpci uid='0x0002' fid='0x00000001'/>
> >> +      <zpci uid='0x0001' fid='0x00000000'/>  
> > 
> > Why this change? The pci-bridge does not show up in the guest anyway.  
> My assumption was that uid and fid for this would be autogenerated.
> Since uid 0x0001 and fid 0x00000000 have been freed up due to the change 
> below this would be the autogenerated set.

If that makes the XML look saner, no objection.

> 
> >   
> >>       </address>
> >>     </controller>
> >>     <interface type='bridge'>
> >>       <source bridge='virbr0'/>
> >>       <model type='virtio'/>
> >>       <address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'>
> >> -      <zpci uid='0x0001' fid='0x00000000'/>
> >> +      <zpci uid='0x0007' fid='0x00000003'/>
> >>       </address>
> >>     </interface>
> >>   
> >> @@ -191,21 +191,22 @@ will result in the following in a Linux guest:
> >>   
> >>   ::
> >>   
> >> -  0001:00:00.0 Ethernet controller: Red Hat, Inc. Virtio network device
> >> +  0007:00:00.0 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.
> >> +topology. Also ``fid`` does not define slot or function of the PCI address.  
> > 
> > I find the sentence regarding 'fid' confusing. Maybe instead move up
> > the explanation from below regarding uid and fid?
> > 
> > "The PCI address in the guest is generated from..."
> >   
> Lets join your proposal with Andreas and move his rewrite up to here.
> Like:
> ...topology.
> The PCI address in the guest is generated from the information provided 
> via the ``zpci`` element: more specifically, ``uid`` is used as the PCI 
> domain.``fid`` doesn't appear in the PCI address itself, but it will be
> used in sysfs (``/sys/bus/pci/slots/$fid/...``).

Sounds good.

(Also the rest of the changes.)