From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.mock.com (gw.mock.com [209.157.146.194]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mail.mock.com", Issuer "CAcert Class 3 Root" (not verified)) by ozlabs.org (Postfix) with ESMTP id 66A3967B89 for ; Tue, 28 Nov 2006 04:39:10 +1100 (EST) Message-ID: <456B22BB.7060301@mock.com> Date: Mon, 27 Nov 2006 09:39:07 -0800 From: Jeff Mock MIME-Version: 1.0 To: Wolfgang Denk Subject: Re: PPC440GX ethernet oddities References: <20061127071454.93C73353A44@atlas.denx.de> In-Reply-To: <20061127071454.93C73353A44@atlas.denx.de> Content-Type: text/plain; charset=ISO-8859-1 Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Wolfgang Denk wrote: > In message <456A641D.7070904@mock.com> you wrote: >> Here's the weird part. On one of the four prototype boxes, if I plug >> the second ethernet port into gigabit switch and get a link light (2nd >> interface is not enabled under linux), the DMA behavior will change and >> I can see the ring buffer get as large as 25MB (up from 512kB!) >> >> Only one of my four boxes shows this strange behavior, and only when the >> second ethernet port is connected to an ethernet switch. Everything > > Are you using exactly the same switch, and the same port on the > switch, and the same network cable with all of your boxen? > Yeah, I'm using the same switch, cables, and server machines for these tests. I've done quite a lot of fiddling with servers, cables, and switches looking for some differential behavior, but the only thing I find is that with second ethernet port unconnected, my ring buffer will consistently only fill to 512kB, but with the second ethernet port connect to get a link light (disabled under linux), the ring buffer will get as full as 25MB over time. jeff