Date: Sat, 05 Dec 2009 08:26:49 +0100 From: Angelo Hongens <angelo@hongens.nl> To: Brooks Davis <brooks@freebsd.org> Cc: "freebsd-current@freebsd.org" <freebsd-current@freebsd.org> Subject: Re: FreeBSD 8.0 problems with interface renaming and dhcp? Message-ID: <4B1A0B39.5060201@hongens.nl> In-Reply-To: <20091204221530.GA42198@lor.one-eyed-alien.net> References: <4B195845.4000201@hongens.nl> <20091204221530.GA42198@lor.one-eyed-alien.net>
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On 04-12-2009 23:15, Brooks Davis wrote: > On Fri, Dec 04, 2009 at 07:43:17PM +0100, Angelo Hongens wrote: >> On most of my BSD machines I rename the interfaces to nic0. This way, I >> can swap cards and drivers, and keep the rest of my config the same. >> >> I upgraded one of these machines from 7.2 to 8.0 (both standard kernel), >> and suddenly the machine would not get a dhcp lease. >> >> In my /etc/rc.conf: >> >> ifconfig_em0_name="nic0" >> ifconfig_nic0="DHCP" >> >> The machine woud boot, but not get an ip. (and no dhclient output while >> booting). And ifconfig would show the nic nic0 up, but without an ip. If >> I do 'dhclient nic0' it immediately gets an ip, and all is well. >> >> If I do NOT rename the interface but just config: ifconfig_em0="DHCP" >> everything works as well.. >> >> So is this a new bug or feature introduced in FreeBSD8? Is it something >> that can be fixed? (So dhclient is executed for renamed interfaces.) > > I think the problem here is that with the new DHCP configuration where > we only start DHCP based on link events we're loosing a race between the > link coming up and the rename occurring. The absolutely correct answer is > that the nic should no be trying to do anything until it is configured > up and I don't think that happens before the rename (it shouldn't). > It's likely the case though that a number of nics incorrectly start doing > things before they are configured and thus racing the rename. The > easiest workaround in the rc.d code would probably be to add some code > to the rename section to take the interface down and then bring it back > up after the rename. That should cause it to renegotiate and generate > an event. > > The no code change workaround is to change DHCP to SYNCDHCP which will > restore the old behavior on this interface. > > -- Brooks Great, configuring SYNCDHCP does exactly what it should do. I'm happy. If I understand you correctly, the long term solution would be to fix the 'em' driver so that it never does anything with an interface until it's configured (in my case: renamed). I never even touched C code, so I hope someone else will look into that ;) -- Met vriendelijke groet, Angelo Höngens
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