From owner-freebsd-hackers@FreeBSD.ORG Tue Mar 22 17:32:21 2011 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8F09E1065675 for ; Tue, 22 Mar 2011 17:32:21 +0000 (UTC) (envelope-from marktinguely@gmail.com) Received: from mail-iy0-f182.google.com (mail-iy0-f182.google.com [209.85.210.182]) by mx1.freebsd.org (Postfix) with ESMTP id 552A78FC1E for ; Tue, 22 Mar 2011 17:32:21 +0000 (UTC) Received: by iyj12 with SMTP id 12so9198774iyj.13 for ; Tue, 22 Mar 2011 10:32:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=jGKk/MKRfa2191jtAJ3viLqLN0qdjsi5nd4Vvu18zhE=; b=deUskqnCaj2kEYBY8a0Wm7hRjElZKvU50yeynsH3OSPfkHIwIWoxV4Ix6u55G6HVDf gwtQPGA4FlbThxrCC0M5yTNonZOIrWVN8YdRLIoHKhV33lf1K0yv7uIvXo+gbuau44hM rcab665pOerSamaBKY2gDQxKrobE5Sz8ryldY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; b=x9EPlemQ29s4sQJQes99L+DJyk+Gb0GII+tfrG8qez22bfcqVM6HajS1yCNX3tvR+I sK6t1oU3EDNPhr2OjiWglSZquB0mtdnnjB6k+aaju+IE5KAbaap0U4BCqstQrsprFe+V J41iGllprwegPFOrvS5B9PdHNr+f4TfrX00Ec= Received: by 10.43.54.18 with SMTP id vs18mr9230240icb.313.1300815140433; Tue, 22 Mar 2011 10:32:20 -0700 (PDT) Received: from [192.168.1.104] (c-24-245-26-12.hsd1.mn.comcast.net [24.245.26.12]) by mx.google.com with ESMTPS id 41sm4518327ibi.10.2011.03.22.10.32.19 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 22 Mar 2011 10:32:19 -0700 (PDT) Message-ID: <4D88DD20.7020104@gmail.com> Date: Tue, 22 Mar 2011 12:32:16 -0500 From: Mark Tinguely User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 MIME-Version: 1.0 To: freebsd-hackers@freebsd.org References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: DMA controller on Northbridge? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Mar 2011 17:32:21 -0000 On 3/22/2011 12:11 PM, Matthew Fleming wrote: > How can I tell if the Northbridge on a machine has a built-in DMA > controller? And if it does, what device would I use to control it? > > I ask because I'm working with a PCI card that has a 36-bit physical > address limit, and that means bounce buffers when using more than 64GB > of memory. I'd prefer not to use bounce buffers, and since the card's > memory that I'm using is mapped into the physical space of the FreeBSD > host, the entire address space of the card that I care about is > available to FreeBSD. So while pio to the card's memory is too slow > to be useful, if there was a way to use a DMA controller on the > motherboard to get data into and out of the card, that may be > preferable to using the card's DMAC with the limited address space. > > But all that's just theory -- I have no idea how to tell whether the > mobo has a DMAC, and if it does, how to control it. Help? :-) > > Attached is the boot dmesg; I can also run pciconf commands, etc., to > help out with figuring out what I have. > > Thanks, > matthew > > > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" Sounds like you are referring to IOMMU: http://software.intel.com/en-us/blogs/2009/03/02/intels-virtualization-for-directed-io-aka-iommu-part-1/ --Mark Tinguely