Re: [dpdk-dev] [PATCH v2] i40e: modify the meaning of single VLAN type

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Jun 21, 2016 at 02:06:38PM +0300, Panu Matilainen wrote:
> On 06/21/2016 01:29 PM, Bruce Richardson wrote:
> >On Mon, Jun 13, 2016 at 04:03:32PM +0800, Beilei Xing wrote:
> >>In current i40e codebase, if single VLAN header is added in a packet,
> >>it's treated as inner VLAN. Generally, a single VLAN header is
> >>treated as the outer VLAN header. So change corresponding register
> >>for single VLAN.
> >>At the meanwhile, change the meanings of inner VLAN and outer VLAN.
> >>
> >>Signed-off-by: Beilei Xing <beilei.xing@intel.com>
> >
> >This patch changes the ABI, since an app written to the original API as specified
> >e.g. to set a single vlan header, would no longer work with this change.
> >Therefore, even though the original behaviour was inconsistent with other drivers
> >it may still need to be preserved.
> >
> >I'm thinking that we may need to provide appropriately versioned copies of the
> >vlan_offload_set and vlan_tpid_set functions for backward compatibility with
> >the old ABI.
> >
> >Any other comments or thoughts on this?
> >Neil, Thomas, Panu - is this fix something that we need to provide backward
> >version-compatibility for, or given that the functions are being called through
> >a generic ethdev API mean that this can just go in as a straight bug-fix?
> 
> Since it's currently inconsistent with everything else, I'd just call it a
> bug-fix and leave it at that.
> 

Yep, makes sense.

> Besides, I dont think you could version it via the ordinary means even if
> you wanted to, due to the way its called through eth_dev_ops etc.
> 

Good point, never thought of that! :-(

> 	- Panu -

Thanks for the guidance.

/Bruce