From owner-freebsd-hackers Thu Mar 5 02:37:55 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id CAA22627 for freebsd-hackers-outgoing; Thu, 5 Mar 1998 02:37:55 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from iclub.nsu.ru (iclub.nsu.ru [193.124.222.66]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA22042 for ; Thu, 5 Mar 1998 02:34:27 -0800 (PST) (envelope-from semen@iclub.nsu.ru) Received: from localhost (semen@localhost) by iclub.nsu.ru (8.8.8/8.8.5) with SMTP id QAA18493; Thu, 5 Mar 1998 16:31:54 +0600 (NS) Date: Thu, 5 Mar 1998 16:31:54 +0600 (NS) From: Ustimenko Semen To: Mike Smith cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Are mbufs aligned or bounded on something? In-Reply-To: <199803042234.OAA22577@dingo.cdrom.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Hello! On Wed, 4 Mar 1998, Mike Smith wrote: > Unless it explicitly matters to your hardware, you should assume that > mbuf clusters are aligned to suit the architecture you're running on. > > If it *does* matter to your hardware, I would be inclined to suggest > that you code to handle all situations, and optimise for the case where > the alignment best suits you. This will greatly improve the > portability of your code. > It realy touch hardware becouse i pass physical address of mtod( caddr_t, mbuf) to hardware, and if it cross the PAGE_SIZE, DMA operation will overwrite some physical address that do not belong to mbuf data area:( To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message