[dpdk-dev] [PATCH] mk: fix missing link of librte_vhost in shared, non-combined config

[Panu Matilainen]

On 02/16/2015 01:17 PM, Thomas Monjalon wrote:
> 2015-02-16 12:01, Panu Matilainen:
>> On 02/13/2015 03:18 PM, Thomas Monjalon wrote:
>>> 2015-02-13 12:33, Panu Matilainen:
>>>> On 02/13/2015 11:28 AM, Thomas Monjalon wrote:
>>>>> 2015-02-13 09:27, Panu Matilainen:
>>>>>> On 02/12/2015 05:44 PM, Thomas Monjalon wrote:
>>>>>>> A library is considered as a plugin if there is no public API and it
>>>>>>> registers itself. That's the case of normal PMD.
>>>>>>> But bonding and Xen have some library parts with public API.
>>>>>>> It has been discussed and agreed for bonding but I'm not aware of the Xen case.
>>>>>>
>>>>>> Fair enough, thanks for the explanation.
>>>>>>
>>>>>> Just wondering about versioning of these things - currently all the PMDs
>>>>>> are versioned as well, which is slightly at odds with their expected
>>>>>> usage, dlopen()'ed items usually are not versioned because it makes the
>>>>>> files moving targets. But if a plugin can be an library too then it
>>>>>> clearly needs to be versioned as well.
>>>>>
>>>>> Not sure to understand your considerations.
>>>>> Plugins must be versioned because there can be some incompatibilities
>>>>> like mbuf rework.
>>>>
>>>> Plugins are version-dependent obviously, but the issue is somewhat
>>>> different from library versioning. Plugins are generally consumers of
>>>> the versioned ABIs, whereas libraries are the providers.
>>>>
>>>>>> I'm just thinking of typical packaging where the unversioned *.so
>>>>>> symlinks are in a -devel subpackage and the versioned libraries are in
>>>>>> the main runtime package. Plugins should be loadable by a stable
>>>>>> unversioned name always, for libraries the linker handles it behind the
>>>>>> scenes. So in packaging these things, plugin *.so links need to be
>>>>>> handled differently (placed into the main package) from others. Not
>>>>>> rocket science to filter by 'pmd' in the name, but a new twist anyway
>>>>>> and easy to get wrong.
>>>>>>
>>>>>> One possibility to make it all more obvious might be having a separate
>>>>>> directory for plugins, the mixed case ccould be handled by symlinks.
>>>>>
>>>>> I think I don't understand which use case you are trying to solve.
>>>>
>>>> Its a usability/documentation issue more than a technical one. If plugin
>>>> DSO's are versioned (like they currently are), then loading them via eg
>>>> -d becomes cumbersome since you need to hunt down and provide the
>>>> versioned name, eg "testpmd -d librte_pmd_pcap.so.1 [...]"
>>>>
>>>> Like said above, it can be worked around by leaving the unversioned
>>>> symlinks in place for plugins in runtime (library) packages, but that
>>>> sort of voids the point of versioning. One possibility would be
>>>> introducing a per-version plugin directory that would be used as the
>>>> default path for dlopen() unless an absolute path is used.
>>>
>>> It makes me think that instead of using a -d option per plugin, why not
>>> adding a -D option to load all plugins from a directory?
>>
>> Are you thinking of "-D <plugindir>" or just -D (to use a build-time
>> hardwired directory)?
>
> I'm thinking of "-D <plugindir>".
> I understand you would like a "hardwired" default directory which would be
> properly packaged by a distribution. Maybe that it could be a build-time
> default to load all the plugins of a directory (without option). Then the
> -d and -D options would overwrite the build-time default behaviour.

Hmm, indeed. What I generally want is software to just DTRT when at all 
possible. For plugins, that typically means "load all installed/enabled 
plugins automatically unless manually overridden".

This becomes even more of an issue if/when the "combine everything" 
libintel_dpdk library in its current form is eliminated (I am fully in 
favor of that) since that has practically hidden the plugins from its 
users like openvswitch.

	- Panu -



	- Panu -