From owner-freebsd-mips@FreeBSD.ORG Mon Dec 10 00:54:18 2012 Return-Path: Delivered-To: mips@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 30ACD2D7 for ; Mon, 10 Dec 2012 00:54:18 +0000 (UTC) (envelope-from imp@bsdimp.com) Received: from mail-ie0-f181.google.com (mail-ie0-f181.google.com [209.85.223.181]) by mx1.freebsd.org (Postfix) with ESMTP id DFE888FC17 for ; Mon, 10 Dec 2012 00:54:17 +0000 (UTC) Received: by mail-ie0-f181.google.com with SMTP id 16so7160708iea.12 for ; Sun, 09 Dec 2012 16:54:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=sender:subject:mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to:x-mailer :x-gm-message-state; bh=NQ/SFUzHRS12x8NX6tNgjKotHD2QRO5QpoGfvtwLETk=; b=Dj5OdkOY4janLQq18h6vVvgCUuVijy0cYfmyt7tm4dl4w3mWmcMvSELG3h6LqxxS8H i/MmMj/ASQHHk9QO7mVNeicWusx6lMw8coervvpysnViQbwNp3dz15B9m//gKcjbRAny 2I5N34wqJfaZx1PmvDzRZqS3fDhvxRH1vxLh5vDbZEWjTsyHrZlbnNo0hr6iqO1WWAEb myNCna5k4DP1razv/2nmRfhIVd6Gr7MlJIvOQQhwLedPHf2H79fuVejGT4WVGgTcPYFP 5jtwLXAV0q4mCrn+v4HJw+X78cvd2rLE3i5oahFGSzalXMfV/Utl6/dUT84jzsLhlb3E KBmA== Received: by 10.50.157.130 with SMTP id wm2mr7911478igb.0.1355100851225; Sun, 09 Dec 2012 16:54:11 -0800 (PST) Received: from 53.imp.bsdimp.com (50-78-194-198-static.hfc.comcastbusiness.net. [50.78.194.198]) by mx.google.com with ESMTPS id l8sm5263808igo.13.2012.12.09.16.54.08 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 09 Dec 2012 16:54:10 -0800 (PST) Sender: Warner Losh Subject: Re: Call for testing and review, busdma changes Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: text/plain; charset=us-ascii From: Warner Losh In-Reply-To: Date: Sun, 9 Dec 2012 17:54:07 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: <1355077061.87661.320.camel@revolution.hippie.lan> To: Jeff Roberson X-Mailer: Apple Mail (2.1085) X-Gm-Message-State: ALoCoQnl3LrA9hFsZsFjIaspHaGNRV4wmqUgZ8A9falTWTaAL4ESkIt5EwFxCYvRwPLIpHwdOceq X-Mailman-Approved-At: Mon, 10 Dec 2012 01:01:54 +0000 Cc: powerpc@freebsd.org, marcel@freebsd.org, mips@freebsd.org, John Baldwin , mav@freebsd.org, scottl@freebsd.org, attilio@freebsd.org, kib@freebsd.org, sparc64@freebsd.org, arm@freebsd.org X-BeenThere: freebsd-mips@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to MIPS List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Dec 2012 00:54:18 -0000 [[ looks like Ian answered the other questions ]] On Dec 9, 2012, at 11:48 AM, Jeff Roberson wrote: >>> The next step is to allow for dma loading of physical addresses. = This >>> will permit unmapped I/O. Which is a significant performance = optimization >>> targeted for 10.0. >>=20 >> This sounds scary for arm and mips, or more specifically for VIVT = cache >> platforms that can only do a sync based on virtual addresses. Can = you >> talk some more about the plans for this? >=20 > It will be for addresses which were never mapped into kva. To support = unmaapped io. There will only be a need for bounce pages, no syncing. If there's a virtual mapping at all for the page (not just a kva), then = we need to flush/invalidate cache for those pages for safety unless we = know for sure there's nothing in the cache. It these are pages that = have never been mapped (say for zero copy between storage and network = controllers), then there won't be a problem. The whole reason for cache = jockeying is to make sure that any pending writes to the data are = flushed, and that any cached notion of the pages are invalidated once = the read is done. This is more important for mbuf operations, = operations with the USB stack or anything else that marshals data it = generates to be consumed by the stack/hardware. Warner