Re: [PATCH net-next] net: remove abuse of VLAN DEI/CFI bit

On Tue, Dec 13, 2016 at 6:03 PM, Michał Mirosław
[off-list ref] wrote:

On Tue, Dec 13, 2016 at 05:21:18PM -0800, Stephen Hemminger wrote:

quoted

On Sat,  3 Dec 2016 10:22:28 +0100 (CET)
Michał Mirosław [off-list ref] wrote:

quoted

This All-in-one patch removes abuse of VLAN CFI bit, so it can be passed
intact through linux networking stack.

Signed-off-by: Michał Mirosław <redacted>
---

Dear NetDevs

I guess this needs to be split to the prep..convert[]..finish sequence,
but if you like it as is, then it's ready.

The biggest question is if the modified interface and vlan_present
is the way to go. This can be changed to use vlan_proto != 0 instead
of an extra flag bit.

As I can't test most of the driver changes, please look at them carefully.
OVS and bridge eyes are especially welcome.

Best Regards,
Michał Mirosław

Is the motivation to support 802.1ad Drop Eligability Indicator (DEI)?

If so then you need to be more verbose in the commit log, and lots more
work is needed. You need to rename fields and validate every place a
driver is using DEI bit to make sure it really does the right thing
on that hardware. It is not just a mechanical change.

My main motivation is to be able to see the bit intact in tcpdump and be
able to pass it untouched through at least a veth pair. It would be great
if all devices didn't do something stupid with the bit, but it's not
something I am able to make happen.

imo "be able to pass untouched through veth" is not good enough
justification for such invasive patches.
I'm still not sure that all of these changes don't affect user space.
_______________________________________________
dev mailing list
dev@openvswitch.org
https://mail.openvswitch.org/mailman/listinfo/ovs-dev