netdev - Re: [PATCH] ixgbe: make VLAN filter conditional in SR-IOV case

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Date:	Fri, 21 Nov 2014 01:28:19 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
Cc:	"e1000-devel@...ts.sourceforge.net" 
	<e1000-devel@...ts.sourceforge.net>,
	Hayato Momma <h-momma@...jp.nec.com>,
	"Choi, Sy Jong" <sy.jong.choi@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] ixgbe: make VLAN filter conditional in SR-IOV case

On Thu, 2014-11-13 at 08:28 +0000, Hiroshi Shimamoto wrote:
> From: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
> 
> Disable hardware VLAN filtering if netdev->features VLAN flag is dropped.
> 
> In SR-IOV case, there is a use case which needs to disable VLAN filter.
> For example, we need to make a network function with VF in virtualized
> environment. That network function may be a software switch, a router
> or etc. It means that that network function will be an end point which
> terminates many VLANs.
> 
> In the current implementation, VLAN filtering always be turned on and
> VF can receive only 63 VLANs. It means that only 63 VLANs can be used
> and it's not enough at all for building a virtual router.
> 
> With this patch, if the user turns VLAN filtering off on the host, VF
> can receive every VLAN packet.
> The behavior is changed only if VLAN filtering is turned off by ethtool.
[...]

What happens when VLAN filtering is turned back on and a VF uses too
many VLANs?  It seems like that should either be prevented (you can't
turn it back on) or the driver should log a message saying the VF is now
broken.

Ben.

-- 
Ben Hutchings
Beware of bugs in the above code;
I have only proved it correct, not tried it. - Donald Knuth

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