Date: Wed, 19 Aug 2009 12:34:05 -0700 From: Julian Elischer <julian@elischer.org> To: Barney Cordoba <barney_cordoba@yahoo.com> Cc: pyunyh@gmail.com, David Christensen <davidch@broadcom.com>, d@delphij.net, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, Jack Vogel <jfvogel@gmail.com>, Jack F Vogel <jfv@freebsd.org>, yongari@freebsd.org Subject: Re: [PATCH] Fix for e1000 (em/igb) NOARP issue [Was Re: em(4): sending ARP regardless of NOARP flag] Message-ID: <4A8C53AD.1040102@elischer.org> In-Reply-To: <121870.41829.qm@web63905.mail.re1.yahoo.com> References: <121870.41829.qm@web63905.mail.re1.yahoo.com>
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Barney Cordoba wrote: > > --- On Tue, 8/18/09, Julian Elischer <julian@elischer.org> wrote: > >> From: Julian Elischer <julian@elischer.org> >> Subject: Re: [PATCH] Fix for e1000 (em/igb) NOARP issue [Was Re: em(4): sending ARP regardless of NOARP flag] >> To: d@delphij.net >> Cc: pyunyh@gmail.com, "Barney Cordoba" <barney_cordoba@yahoo.com>, "David Christensen" <davidch@broadcom.com>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, "Jack Vogel" <jfvogel@gmail.com>, "Jack F Vogel" <jfv@freebsd.org>, yongari@freebsd.org >> Date: Tuesday, August 18, 2009, 6:55 PM >> Xin LI wrote: >>> -----BEGIN PGP SIGNED MESSAGE----- >>> Hash: SHA1 >>> >>> Barney Cordoba wrote: >>>> --- On Tue, 8/18/09, Pyun YongHyeon <pyunyh@gmail.com> >> wrote: >>>>> From: Pyun YongHyeon <pyunyh@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@delphij.net> >>>>> Cc: "Barney Cordoba" <barney_cordoba@yahoo.com>, >> "David Christensen" <davidch@broadcom.com>, >> "d@delphij..net" >> <d@delphij.net>, >> "freebsd-net@freebsd.org" >> <freebsd-net@freebsd.org>, >> "Jack Vogel" <jfvogel@gmail.com>, >> "Jack F Vogel" <jfv@freebsd.org>, >> yongari@freebsd.org, >> "Julian Elischer" <julian@elischer.org> >>>>> Date: Tuesday, August 18, 2009, 5:49 PM >>>>> On Tue, Aug 18, 2009 at 02:03:37PM >>>>> -0700, Xin LI wrote: >>>>>> -----BEGIN PGP SIGNED MESSAGE----- >>>>>> Hash: SHA1 >>>>>> >>>>>> 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. > > > Ah, are they running Jack's drivers unmodified? Seems unlikely. well they will be when they go to 8. They stay a revision or two back for stability reasons of course. why wouldn't they? > > NOARP does work. Does your network catch on fire if the interface sends > an ARP out? Does equipment start failing like dominos? well if your network sniffer started responding to arps, how would you feel? > > My point was don't make ARPs not work (the reason the "hack" is in > there is to make something work better) to preserve some fantasy of > "layering" that went out with the 8-track player. The check for > the NOARP flag is a better solution until the subsystem works the > way its supposed to work. > > Barney > > >
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