linux-kernel - VLAN tag stacking with bridge/tap device ?

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Message-ID: <20190814202951.20d7dff1@ithnet.com>
Date:   Wed, 14 Aug 2019 20:29:51 +0200
From:   Stephan von Krawczynski <skraw.ml@...net.com>
To:     linux-kernel@...r.kernel.org
Subject: VLAN tag stacking with bridge/tap device ?

Hello all,

I try to do a setup with qemu and tap devices attached to bridges where 802.1Q
vlan packets that are tag stacked are running through the tap device/bridge
where the outer tag is stripped. But it seems on the way back out of
qemu/guest and back through the tap and bridge no additional vlan tags are
added back.
The very same setup with only one vlan tag that is stripped and added back
works as expected. Is there something in the tap device or bridge code that
prevents stacking? Can this be done by configuration or by additional coding
in the tap or bridge?

-- 
Regards,
Stephan

PS: please add me as cc in reply