From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19252 invoked by alias); 12 Jun 2007 19:35:33 -0000 Received: (qmail 19239 invoked by uid 22791); 12 Jun 2007 19:35:31 -0000 X-Spam-Check-By: sourceware.org Received: from hoboe2bl1.telenet-ops.be (HELO hoboe2bl1.telenet-ops.be) (195.130.137.73) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 12 Jun 2007 19:35:28 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by hoboe2bl1.telenet-ops.be (Postfix) with SMTP id 32978124092; Tue, 12 Jun 2007 21:35:26 +0200 (CEST) Received: from [127.0.0.1] (d51A48CEA.access.telenet.be [81.164.140.234]) by hoboe2bl1.telenet-ops.be (Postfix) with ESMTP id 14D20124072; Tue, 12 Jun 2007 21:35:26 +0200 (CEST) Message-ID: <466EF583.2090003@telenet.be> Date: Tue, 12 Jun 2007 22:46:00 -0000 From: =?ISO-8859-1?Q?J=FCrgen_Lambrecht?= Reply-To: Juergen Lambrecht User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 To: Andrew Lunn , ecos-discuss@ecos.sourceware.org References: <466EC08A.8090704@televic.com> <20070612160753.GP26816@lunn.ch> In-Reply-To: <20070612160753.GP26816@lunn.ch> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Subject: Re: [ECOS] max IP packet size = 9216 B. Why? X-SW-Source: 2007-06/txt/msg00132.txt.bz2 Andrew Lunn wrote: > On Tue, Jun 12, 2007 at 05:49:30PM +0200, J?rgen Lambrecht wrote: > >> Hello, >> >> I found out that the maximum IP packet size = 9216 B (0x2400). >> I implemented an echo program, both udp and tcp. >> My ecos applic can receive more that 9216B, but not send back more than >> that. >> >> Has anybody a clue how to solve this? >> I need to support the maximum IP packet size of 65535 B (IP_MAXPACKET). >> > > Interesting. What network technology do you have underneath > this. Something reliable i presume since even small packet error rates > are going to cause big delay and inefficiencies with retries. > Don't tell me! Our customer is very stubborn.. Because the maximum size of an IP packet is 64KB, their suppliers (us) _must_ support it. We must support IP. > >> I don't know if this is a bug in ecos, or a (hidden?) limitation of an >> embedded OS. >> > > I don't know of anybody else using nearly jumbo packets. So you might > be running into bugs, or configuration tweaks might be needed. > It has nothing to do with Ethernet Jumbo frames. We use the standart Ethernet MTU 1518B. The IP layer is responsible of fragmenting the IP packets to fit the MAC's layer MTU. > >> I'm busy tracing this back in the source >> This comes from the socket that is allocated statically in >> /io/fileio/.../fd.cxx and socket is part of a cyg_file (cyg_file is >> defined by file in file.h). In cyg_file there is a member f_data, which >> is the socket. >> I'm continuing my search in the code at this point.... >> > > Do you get a crash, or does write/sendto return an error code? > sendto returns the error code 322 or EMSGSIZE "Message too long". I forgot to tell that's because the high water level of the send socket (o->so_snd.sb_hiwat) is 9216 B (=0x2400) (in file bsd_tcpip/current/src/sys/kern/uipc_socket.c:523). I will try to increase the socket's high water level (after I have found where it is set ;-). Kind regards, Juergen > Andrew > > > -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss