From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-vbr15.xs4all.nl (smtp-vbr15.xs4all.nl [194.109.24.35]) by ozlabs.org (Postfix) with ESMTP id DACC9DDF2D for ; Fri, 7 Mar 2008 19:03:32 +1100 (EST) Message-ID: <47D0F479.4050109@aimvalley.nl> Date: Fri, 07 Mar 2008 08:53:29 +0100 From: Norbert van Bolhuis MIME-Version: 1.0 To: rmcguire@videopresence.com Subject: Re: RAW Sockets - HDLC or Ethernet References: <000001c87f6b$e1d5e9e0$6405a8c0@absolut> In-Reply-To: <000001c87f6b$e1d5e9e0$6405a8c0@absolut> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , I guess this is what a raw packet socket is supposed to do. It's not a bug it's a feature. Can't you somehow recognize your own packet (and skip it) ? Btw. this question can probably be better addressed in comp.os.linux.development.system --- N. van Bolhuis. Russell McGuire wrote: > Anyone, > > Yet another mysterious question, at least to me. > > I have written to simple utilities to send and receive a file / data through > a newly created driver, HDLC using an MPC8360E. > Though I doubt this question is limited to that specific HW. > > The main question is that everything I send though device HDLC0 I can > immediately read from HDLC0 even though logically there is no connection > there. It as if the kernel is immediately allowing me to read from the same > device, what a separate application just wrote.??? > HOW CAN THIS BE? > > Details: > I have two applications: send and receive. (pseudo code as follows) > > Send opens a socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)). > And binds it (AF_PACKET, ETH_P_HLDC, if_index(hdlc0)) > > Receive opens a socket to the same device > socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)) > bind(AF_PACKET, ETH_P_ALL, if_index(hdlc0) > > Note they are opening the same device. > > Now if I send anything through the send application, I immediately receive > it via the receive application?? > Note, entirely separate processes! > > Note, there is NO hardware loopback, this should be a dead end, and I should > get nothing back at least as far as HW is concerned. > > What am I missing, that causes all my TX data to show up immediately in the > RX app? Note I have verified my HDLC drier is not actually receiving > anything, so is there something in the kernel that is bridging the TX / RX > paths, or am I just missing the function of this? If so how can I use RAW > mode, while not mixing this, or at least keeping them separate in the > applications? > > -Russ > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded -- This message has been scanned for viruses and is believed to be clean