Netmap ixgbe stripping Vlan tags

[Luigi Rizzo]

responding to the first email in the thread:

netmap by design does not modify the setting of the card
(vlan, hwcsum, tso/lro, promisc, ...).

The main practical reasons behind this choice are that
i) in many cases both settings make sense when in netmap mode,
ii) we can use existing OS tools/ioctl to modify the settings
without having to replicate them within the netmap code.

vlan tag insertion/removal is probably the one feature which
should be always disabled in netmap mode. For others, the case
is not so clear.

As an example, having tso and hwcsum enabled is useful
to postpone those expensive ops to the very last moment;
the upcoming version of netmap supports scatter-gather I/O,
and when used to interconnect virtual machines through
the VALE switch you don't even need to do the segmentation
or checksumming.

cheers
luigi



On Fri, Aug 23, 2013 at 12:36 AM, Harika Tandra <htandra at gloriad.org> wrote:

> Hi all,
>
> I am running Netmap with "intel 10G 82598EB" card in promiscuous mode.
> While capturing packets via Netmap the driver is stripping off Vlan tags.
> I tested my setup, I am able to see Vlan tags when the same card is in
> promiscuous
> mode without Netmap.
>
> This maybe due to the netmap related changes to the device driver code.
> But I don't know much about drivers. I would appreciate any help or pointer
> regarding this.
>
> Thanks,
> Htandra.
>
>
>
>
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