From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt To: , , "Kevin B. Hendricks" Subject: Re: Weird bug problems with timing of NIC driver loading? Date: Sat, 16 Feb 2002 20:22:33 +0100 Message-Id: <20020216192233.13014@smtp.wanadoo.fr> In-Reply-To: <9382917A-2286-11D6-9EE3-0003938E434C@ivey.uwo.ca> References: <9382917A-2286-11D6-9EE3-0003938E434C@ivey.uwo.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: > >Hi, > >I have a weird bug report I need some help tracking down: > >With both the G3 using either tulip or bmac NICs and the new G4 using >Sungmem I can reliably and repeatedly show funky net behavior when those >drivers are compiled in or loaded early in the boot process as modules. > >This behavior is funny in that ifconfig shows no errors and that packets >are being sent and received (and the lights on the cards seem to support >that) but none of the received info ever seems to make it back upstream >from the card (a receive buffer alignment issue?) > >This is repeatable with both machines and with BMAC, TULIP, and SUNGEM >when compiled in or loaded as a module during the normal eth0 >initialization during bootup > >If I simply compile them as modules and wait until the machine is up and >simply do an insmod and configure the network, they ALL work absolutely >perfectly. That is weird, you are the first person to report such a problem, and since such a broad range of HW is affected, I'd rather blame some other kernel routing problem, possibly some setup of your init scripts, (or some ECN issue ?) >So whatever the issue is, it seems to be related to when in the boot >process the NIC code is invoked. > >Is this due to some change in memory mapping? No, nothing here should matter. >Is this due to some change in IRQ assignment? Neither. IRQ assignement isn't changed, it comes from the firmware and works on all known HW. >Is this due to some alignment issue with DMA buffers and memory / caches? I don't think so, especially recent machines have no known cache coherency problems. >So what is different when a module is loaded by modprobe during the eth0 >initialization during bootup versus waiting until the end and then >running insmod to load the module and configure the network. > >Just to check I made sure there were no firewall modules loaded at all >and that the network routing tables and things were set properly >(identical to the hand done case at the end of boot-up). > >This problem seems to exist in every 2.4.X kernel I have tried. > >This problem does not exist in 2.2.X kernels. That's weird, it could well be an ecn problem. Do you have a switch or a hub ? to what machine are you trying to talk to ? It really look like a problem above the drivers. Ben. ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/