netdev - RE: [PATCH 10/27] ixgb: Don't check for vlan group on transmit

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Date:	Mon, 13 Dec 2010 11:43:01 -0700
From:	"Tantilov, Emil S" <emil.s.tantilov@...el.com>
To:	Jesse Gross <jesse@...ira.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"gospo@...hat.com" <gospo@...hat.com>,
	"bphilips@...ell.com" <bphilips@...ell.com>
Subject: RE: [PATCH 10/27] ixgb: Don't check for vlan group on transmit

>-----Original Message-----
>From: Jesse Gross [mailto:jesse@...ira.com]
>Sent: Sunday, December 12, 2010 5:01 PM
>To: Kirsher, Jeffrey T
>Cc: davem@...emloft.net; Tantilov, Emil S; netdev@...r.kernel.org;
>gospo@...hat.com; bphilips@...ell.com
>Subject: Re: [PATCH 10/27] ixgb: Don't check for vlan group on transmit
>
>On Fri, Dec 10, 2010 at 10:17 PM, Jeff Kirsher
><jeffrey.t.kirsher@...el.com> wrote:
>> From: Emil Tantilov <emil.s.tantilov@...el.com>
>>
>> Based on a patch from Jesse Gross.
>>
>> Enable vlan tag insertion even when vlan group is not configured.
>>
>> For ixgb HW both CTRL0.VME and VLE bit in the Tx descriptor need to be
>set
>> in order to enable HW acceleration.
>>
>> Introduced separate functions for enabling/disabling of vlan tag
>stripping
>> similar to ixgbe.
>
>Thanks for working on this.  However, I don't think that this patch
>actually does what it says.
>
>In ixgb_xmit_frame() it's still checking whether adapter->vlgrp is
>non-null before inserting a tag, so it will drop tags unless a vlan
>group is configured.  Also, since it's not currently possible to
>toggle NETIF_F_HW_VLAN_RX, vlan stripping will never get disabled.
>This is actually a regression since before vlan stripping would get
>disabled if no vlan group was configured.  Now, vlan headers will get
>silently dropped if there is no vlan group.
I'm sorry. This patch was supposed to include your original patch that 
removed the vlgrp check on Tx. Somehow that didn't make it (I may have generated the patch from the wrong branch).

>Regardless of that, I still think this is a useful change on the road
>towards adopting the new vlan interfaces, the problem is just that
>currently it's halfway in between the old and the new.  Given that, it
>would obviously be much better to move all the way over the new when
>addressing this.
Since this patch is already applied can you submit your change again?

>Out of curiosity, is the implication of this that vlan insertion on
>transmit and stripping on receive are always configured together?  I
>don't have hardware supported by this driver but when I worked on
>ixgbe (which is at least superficially similar in this area) I didn't
>have any problems configuring them independently.

Yes - the design of the original 10GB HW supported in ixgb does not allow 
setting Tx and Rx independently. As you mentioned ixgbe does not have 
this problem.

>
>Thanks.

Thanks,
Emil

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