[ovs-dev] [dp version v6] bridge: Store datapath version into ovsdb

Andy Zhou azhou at nicira.com
Wed Nov 5 23:27:36 UTC 2014


Pushed with the xml updates. Ben, Thanks for the wirte-up and review!

On Wed, Nov 5, 2014 at 1:59 PM, Ben Pfaff <blp at nicira.com> wrote:
> On Wed, Nov 05, 2014 at 01:32:32PM -0800, Andy Zhou wrote:
>> OVS userspace are backward compatible with older Linux kernel modules.
>> However, not having the most up-to-date datapath kernel modules can
>> some times lead to user confusion. Storing the datapath version in
>> OVSDB allows management software to check and optionally provide
>> notifications to users.
>>
>> Signed-off-by: Andy Zhou <azhou at nicira.com>
>
> Acked-by: Ben Pfaff <blp at nicira.com>
>
> I think that the documentation could use some elaboration.  First a
> few typos:
>> +      <column name="datapath_version">
>> +        Reports the Open vSwitch datapath version in use.  If the bridge
>> +        uses a datapath that is  linked into ovsvswitchd, "&lt;built-in&gt;"
>> +        will be stored, in liue of the actual version. If datapath version
>> +        cannot be determined, "&lt;unknown&gt;" will be stored.
>> +      </column>
>
> s/ovsvswitchd/ovs-vswitchd/
> s/liue/lieu/
>
> But I'd add some text too that explains what this is good for.  Maybe
> like this:
>
>       <column name="datapath_version">
>         <p>
>           Reports the version number of the Open vSwitch datapath in use.  This
>           allows management software to detect and report discrepancies between
>           Open vSwitch userspace and datapath versions.  (The <ref
>           column="ovs_version" table="Open_vSwitch"/> column in the <ref
>           table="Open_vSwitch"/> reports the Open vSwitch userspace version.)
>           The version reported depends on the datapath in use:
>         </p>
>
>         <ul>
>           <li>
>             When the kernel module included in the Open vSwitch source tree is
>             used, this column reports the Open vSwitch version from which the
>             module was taken.
>           </li>
>
>           <li>
>             When the kernel module that is part of the upstream Linux kernel is
>             used, this column reports <code>&lt;unknown&gt;</code>.
>           </li>
>
>           <li>
>             When the datapath is built into the <code>ovs-vswitchd</code>
>             binary, this column reports <code>&lt;built-in&gt;</code>.  A
>             built-in datapath is by definition the same version as the rest of
>             the Open VSwitch userspace.
>           </li>
>
>           <li>
>             Other datapaths (such as the Hyper-V kernel datapath) currently
>             report <code>&lt;unknown&gt;</code>.
>           </li>
>         </ul>
>
>         <p>
>           A version discrepancy between <code>ovs-vswitchd</code> and the
>           datapath in use is not normally cause for alarm.  The Open vSwitch
>           kernel datapaths for Linux and Hyper-V, in particular, are designed
>           for maximum inter-version compatibility: any userspace version works
>           with with any kernel version.  Some reasons do exist to insist on
>           particular user/kernel pairings.  First, newer kernel versions add
>           new features, that can only be used by new-enough userspace, e.g.
>           VXLAN tunneling requires certain minimal userspace and kernel
>           versions.  Second, as an extension to the first reason, some newer
>           kernel versions add new features for enhancing performance that only
>           new-enough userspace versions can take advantage of.
>         </p>
>       </column>
>



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