linux-kernel - Re: Problem with e1000e, 802.1Q VLAN's and IPMI

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Message-ID: <20100727120552.GA31741@centrinvest.ru>
Date:	Tue, 27 Jul 2010 16:05:52 +0400
From:	"Andrey Panin" <pazke@...trinvest.ru>
To:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"e1000-devel@...ts.sourceforge.net" 
	<e1000-devel@...ts.sourceforge.net>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"Allan, Bruce W" <bruce.w.allan@...el.com>,
	"Duyck, Alexander H" <alexander.h.duyck@...el.com>,
	"Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr@...el.com>,
	"Ronciak, John" <john.ronciak@...el.com>
Subject: Re: Problem with e1000e, 802.1Q VLAN's and IPMI

On 207, 07 26, 2010 at 09:45:06AM -0700, Brandeburg, Jesse wrote:
> 
> On Mon, 26 Jul 2010, Andrey Panin wrote:
> > I have a problem using IPMI on Super Micro X7SBL motherboard (AOC-IPMI20-E BMC).
> > BMC shares ethernet port with onboard e1000e. It works when IPMI traffic is 
> > untagged (CrcStripping=0 module option used), but if I try to use 802.1Q vlan
> > for IPMI traffic BMC stops responding right after "ifup eth0". 
> 
> We've heard of this issue (or similar) before.  I believe for the other 
> guys they had to run IPMI traffic untagged, if your main network is 
> running untagged.  The problem in this case is that the tags are being 
> stripped in hardware even for the SMBUS packets, at which point the BMC 
> that is stupid and doesn't understand offloading hardware gets confused 
> that the traffic it is receiving doesn't have a vlan tag.

I suspected something like that. Unfortunately Super Micro isn't interested
in fixing their BMC, at least latest firmware doesn't fix the issue.

> > I tested 2.6.26 (debian stable kernel) and 2.6.35-rc6.
> > Looks like there is some problem with 802.1Q tags stripping/inserting.
> 
> Thanks for testing the latest kernel.
> 
> > There was no such problem with e1000 driver from 2.6.18.
> 
> Hm, that is an interesting statement.  The major changes to the driver 
> include stripping tags all the time when not in promisc mode, and there 
> have been some fixes and attempts to fix the ipmi issues some 
> (particularly supermicro) BMCs have.  I'm quite surprised it worked for 
> you at all (there have been quite a few issues in this area)

After some sleep I'm not so sure that it was really working :(
I'll retest it more thoroughly this evening.

> > Unfortunately I can't provide additional info right now, but I can provide
> > it slightly later and I'm ready to test patches.
> 
> I can send you a patch to disable vlan stripping in hardware which will 
> probably get you working, but I don't think it is production worthy.

This solution looks too drastic to me, taking into account that this box will
be used as broadband access server. I'll better change my network to keep IPMI
traffic untagged.

Best regards.

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