[PATCH v2 20/29] domain_conf: format pnv-phb3-root-port empty addr

[Daniel Henrique Barboza]

On 2/21/22 10:36, Ján Tomko wrote:
> On a Tuesday in 2022, Daniel Henrique Barboza wrote:
>> Hiding the empty (0000:00:0.0) PCI address in the case of devices that
>> will connect to slot 0x0 can be counterintuitive to the user, which will
>> see something like this:
>>
>>    <controller type='pci' index='0' model='pcie-root'/>
>>    <controller type='pci' index='1' model='pcie-root-port'>
>>      <model name='pnv-phb3-root-port'/>
>>      <target chassis='1' port='0x8'/>
>>    </controller>
>>
>> Even if the user deliberately adds the root-port <address> element:
>>
>>    <address type='pci' domain='0x0000' bus='0x00' slot='0x00' function='0x0'/>
>>
>> We end up removing the <address> element after saving the domain file.
>> This happens because virPCIDeviceAddressIsEmpty() can't distinguish
>> between a zeroed address that was set by the user versus an address that
>> wasn't filled at all.
> 
> I'm afraid this is incomplete.
> 
> virPCIDeviceAddressIsEmpty is for example used to figure out whether the
> device needs an address assigned too.
> 
> So we'll need an extra field to distinguish between empty and
> zero addresses, which will probably need adjustment in a lot of callers
> :(

Hmmm I don't think this is a hill I want to die on in this series.

This patch is already adding a "VIR_DOMAIN_DEF_FORMAT_EMPTY_PCI_ADDR" flag to force
the address formatting regardless of virPCIDeviceAddressIsEmpty(). I believe that
I can rename it to "VIR_DOMAIN_DEF_FORMAT_PCI_ADDR", making it clear that the idea is
to force the <addr> formatting at all times for the device, regardless of any assumptions
about the address being empty, or not assigned, or any other cases where
virPCIDeviceAddressIsEmpty() might apply.


Thanks,


Daniel




> 
> Jano
> 
>>
>> Given that all root-ports of PowerNV domains will connect to slot 0 of
>> the PHB, if the PHB controller has index = 0 this scenario will occur
>> every time. This patch aims to alleaviate this behavior by adding a new
>> virDomainDefFormatFlags that will allow an empty address to be formatted
>> in the XML. This flag is then used only when formatting PowerNV root
>> ports.
>>
>> Signed-off-by: Daniel Henrique Barboza <danielhb413 at gmail.com>
>> ---
>> src/conf/domain_conf.c | 25 ++++++++++++++++++++++++-
>> src/conf/domain_conf.h |  2 ++
>> 2 files changed, 26 insertions(+), 1 deletion(-)
>>