From owner-freebsd-arm@FreeBSD.ORG Sun Jun 29 03:44:41 2014 Return-Path: Delivered-To: arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 99C46E22 for ; Sun, 29 Jun 2014 03:44:41 +0000 (UTC) Received: from mail-qa0-x229.google.com (mail-qa0-x229.google.com [IPv6:2607:f8b0:400d:c00::229]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5DD032326 for ; Sun, 29 Jun 2014 03:44:41 +0000 (UTC) Received: by mail-qa0-f41.google.com with SMTP id cm18so5377274qab.28 for ; Sat, 28 Jun 2014 20:44:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:content-type; bh=lVNjNeYsPPOZmgohGGPsgKTP/jIgk+looODjoTsAHp0=; b=WmLFMtc5Lp7L2R+p4phGfQ5LXwSm1MD+wbqD578Tky1cQQPzz0Y4YwV0I7c/26pVJI h5kmevU1k8E50/9tImQ0jVaKxRYM1AP/1oYvkGCX2Z0PZZQohO56X5ZrshqS/V9ZSrn1 Ir/yLyJzdNpQtPzLgjHNxzfSxoHcYZaR540Z4Umb96T4ayi7xEpiAGMjPI4/WaA2khrb qpNKaUtDoej5izrNvwXimX4/6+gkgxz+MnPpO1UysVVaOmlw1DYRYFCQ0zJNk0rfftO4 MVJka+r9Hm7aOFS6R/w8BAmFPqFZc2m6tuGz/Olyv8ZD9bWZhF97xOkTM/qATZe0J9VT 8LEg== MIME-Version: 1.0 X-Received: by 10.224.66.70 with SMTP id m6mr49949130qai.55.1404013480454; Sat, 28 Jun 2014 20:44:40 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.224.202.193 with HTTP; Sat, 28 Jun 2014 20:44:40 -0700 (PDT) In-Reply-To: <20140629033823.GN1560@funkthat.com> References: <20140629033823.GN1560@funkthat.com> Date: Sat, 28 Jun 2014 20:44:40 -0700 X-Google-Sender-Auth: ue_izXNgT-ED6I8ZN0kZOqVNa14 Message-ID: Subject: Re: arm alignment faults... From: Adrian Chadd To: "freebsd-arm@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Jun 2014 03:44:41 -0000 On 28 June 2014 20:38, John-Mark Gurney wrote: > So, one of the little projects I'd like to see is the removal of > ETHER_ALIGN from the tree.. This bogosity can (and does) cause the use > of bouncing durning DMA ops on all ethernet frames... Well, as long as you're not doing it by forcing the various CPUs to handle unaligned accesses. The cost of those unaligned accesses on some CPUs that support them is not trivial. We benchmarked some of the ARM cores at Qualcomm back when looking to migrate stuff to ARM and it wasn't very quick. -a