netdev - Re: [PATCH][net-next][v2] bridge: allow the maximum mtu to 64k

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Date:	Wed, 24 Feb 2016 15:57:17 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	roy.qing.li@...il.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH][net-next][v2] bridge: allow the maximum mtu to 64k

From: roy.qing.li@...il.com
Date: Tue, 23 Feb 2016 09:00:56 +0800

> This is especially annoying for the virtualization case because the
> KVM's tap driver will by default adopt the bridge's MTU on startup
> making it impossible (without the workaround) to use a large MTU on the
> guest VMs.

So if the TAP device adopts the bridge's MTU, and then a device is
enslaved to the bridge that has a "smaller than 64k" MTU, what
propagates that MTU change back to the TAP device?

I really want to understand how this is supposed to work.