From owner-freebsd-questions Thu May 9 4:58:14 2002 Delivered-To: freebsd-questions@freebsd.org Received: from natsemi-bh.nsc.com (natsemi-bh.nsc.com [204.163.202.66]) by hub.freebsd.org (Postfix) with ESMTP id 28B2837B404 for ; Thu, 9 May 2002 04:58:11 -0700 (PDT) Received: (from uucp@localhost) by natsemi-bh.nsc.com (8.8.8/8.6.11) id EAA10941 for ; Thu, 9 May 2002 04:58:07 -0700 (PDT) Received: from nsc.nsc.com(139.187.81.1) by natsemi-bh.nsc.com via smap (4.1) id xma010933; Thu, 9 May 02 04:57:36 -0700 Received: from malkauns.malkauns.nsc.com (malkauns.nsc.com [139.187.83.131]) by nsc.nsc.com (8.10.2+Sun/8.10.2) with SMTP id g49BvVS24073 for ; Thu, 9 May 2002 04:57:31 -0700 (PDT) Received: from malkauns.nsc.com by malkauns.malkauns.nsc.com (SMI-8.6/SMI-SVR4) id RAA10381; Thu, 9 May 2002 17:33:04 +0530 Message-ID: <3CDA652A.930BB5BF@malkauns.nsc.com> Date: Thu, 09 May 2002 17:31:46 +0530 From: shubhamr Reply-To: shubhamr@malkauns.nsc.com X-Mailer: Mozilla 4.7 [en] (WinNT; I) X-Accept-Language: en MIME-Version: 1.0 To: "questions@FreeBSD.ORG" Subject: mbuf doubt - please help urgent. Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Hi , I see in one of the sample drivers for the NIC that for transmission,"mtod" and "vtophys" has been used. But why have not they considered the case if mbuf data resides in various chunks in physical memory,mtod will no more help for the sake of DMAing? Or is it that whenever the higer layers give data to be transferred , it will be guarentted that they reside contiguous?Also I read somewhere that mtod functions work only when the data is embedded into the structure and not externally in mbuf clusters? Please reply. Thanks a lot in advance, shubha To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message