[PATCH] Fix for e1000 (em/igb) NOARP issue [Was Re: em(4): sending ARP regardless of NOARP flag]

[Julian Elischer]

Xin LI wrote:
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> Barney Cordoba wrote:
>> --- On Tue, 8/18/09, Pyun YongHyeon <pyunyh at gmail.com> wrote:
>>
>>> From: Pyun YongHyeon <pyunyh at gmail.com>
>>> Subject: Re: [PATCH] Fix for e1000 (em/igb) NOARP issue [Was Re: em(4): sending ARP regardless of NOARP flag]
>>> To: "Xin LI" <delphij at delphij.net>
>>> Cc: "Barney Cordoba" <barney_cordoba at yahoo.com>, "David Christensen" <davidch at broadcom.com>, "d at delphij..net" <d at delphij.net>, "freebsd-net at freebsd.org" <freebsd-net at freebsd.org>, "Jack Vogel" <jfvogel at gmail.com>, "Jack F Vogel" <jfv at freebsd.org>, yongari at freebsd.org, "Julian Elischer" <julian at elischer.org>
>>> Date: Tuesday, August 18, 2009, 5:49 PM
>>> On Tue, Aug 18, 2009 at 02:03:37PM
>>> -0700, Xin LI wrote:
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>>>> Hi, Jack,
>>>>
>>>> I have looked into the code history and found that
>>> sys/dev/em/if_em.c,v
>>>> 1.119 has introduced the arp_ifinit() call in order to
>>> fix the problem
>>>> that if_em won't send ARP when IP address is changed.
>>>>
>>>> I think we can further improve it as attached, say,
>>> only do it when
>>>> IFF_NOARP is not set.  This should have no effect
>>> for usual
>>>> configuration but fix the problem when NOARP is the
>>> desired behavior.
>>> That change was introduced by me. I guess the root cause of
>>> the
>>> problem was long initialization time of hardware which in
>>> turn
>>> resulted in unbearable boot time when multiple-alias
>>> addresses are
>>> assigned to em(4). I don't remember details,though.
>>>
>>> Since we're in the release cycle, the change you suggested
>>> would be
>>> quick fix for 8.0. I think em(4)/igb(4) should remove
>>> SIOCSIFADDR
>>> handling in driver which is layering violation.
>> There are 2 kinds of programmers; those who do things "correctly',
>> and those that do things that work. 
>>
>> 99.99999% of the people will be using ARPs, so don't be silly and
>> break the driver to solve a case that almost no-one cares about please.
> 

Cisco.Ironport  runs 50% (2 out of 4) of their em interfaces in noarp 
mode.
  please keep noarp working!


> I see no reason how you have reached the "99.99999%" conclusion.  My
> employer for instance, has several millions of dollars worth of hardware
> purchase every year, and, we do care about DSR, or NOARP being working
> or not.
> 
> Cheers,
> - --
> Xin LI <delphij at delphij.net>	http://www.delphij.net/
> FreeBSD - The Power to Serve!
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