Date: Tue, 3 Sep 2002 12:55:03 -0600 From: "Kenneth D. Merry" <ken@kdm.org> To: Luigi Rizzo <rizzo@icir.org> Cc: Charles Sprickman <spork@inch.com>, freebsd-net@FreeBSD.ORG Subject: Re: fxp and 802.3 flow control Message-ID: <20020903125503.A95848@panzer.kdm.org> In-Reply-To: <20020903114028.B1595@iguana.icir.org>; from rizzo@icir.org on Tue, Sep 03, 2002 at 11:40:28AM -0700 References: <Pine.BSF.4.44.0208292128480.18885-100000@shell.inch.com> <20020903123508.A95635@panzer.kdm.org> <20020903114028.B1595@iguana.icir.org>
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On Tue, Sep 03, 2002 at 11:40:28 -0700, Luigi Rizzo wrote: > i wouldn't call the thing a "problem" -- flow control packets are > a feature which you can enable or disable. > I have used something similar to your patch below, and noticed that > just setting tx_fc_dis=1 (check the comment, btw) makes these > frames disappear, i suppose that setting the bit causes some negotiation > with the peer that disables their generation on both sides. Flow control isn't a problem in and of itself. The problem is that the card is passing flow control frames up to the OS, which can't do anything about it. The flow control frames are supposed to be intercepted by the card and used to turn on and off transmit. When tx_fc_dis = 0, it's anybody's guess as to whether the card is doing anything with the flow control frames, but it is clear that they get passed up to the host. This seems to happen regardless of the value of fc_filter. With tx_fc_dis=1, I think fc_filter works as intended (not sure, I'd have to go test it again), but I just turn it on all the time, since I don't want to see the flow control packets, even in promiscuous mode. They just cloud up whatever I'm trying to look at. It would be nice if there were actually detailed docs available for those boards that didn't require an NDA. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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