From owner-freebsd-hackers@FreeBSD.ORG Mon Feb 2 08:45:18 2009 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 E803E10656D2 for ; Mon, 2 Feb 2009 08:45:18 +0000 (UTC) (envelope-from yanefbsd@gmail.com) Received: from mail-fx0-f10.google.com (mail-fx0-f10.google.com [209.85.220.10]) by mx1.freebsd.org (Postfix) with ESMTP id 4588A8FC12 for ; Mon, 2 Feb 2009 08:45:17 +0000 (UTC) (envelope-from yanefbsd@gmail.com) Received: by fxm3 with SMTP id 3so1251628fxm.19 for ; Mon, 02 Feb 2009 00:45:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=9kOr6Bgiyf4TtC2a/aNHiFZSh2ozyBpMXa/97U5prt4=; b=gidHjBqi3yETzg7Srna8eLvQk4Ovzivz6Sg0F2X+l4KbneZEiRYXoBG/lDihVzXumI IlGlmanpMdpbgPgI5cUgp2p1Equ7ZK3mRHrVA8WAWy20yOFkDSZCZijXKIuX+LWbhdzq 39JeDbW7H2VCIIt/4AN6uI+eL0+iCbPzic/hE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=g6sibm/jkt9E7cDkURqlyhoncoO1nTquZ597bxIb6iJEeZNNF+P2nO6vF6E8fT0Ga4 lYPlCwmhFX0+WPbEc6zx5x6oF5PmR8ebadt66UzacWx235ZeVJ5v5raRhLaI6Nz1QXvm 2XcnFJZ1TCe2cnDQqkh/JvQm9XgqX0PeITRgQ= MIME-Version: 1.0 Received: by 10.181.226.19 with SMTP id d19mr1598908bkr.35.1233564315902; Mon, 02 Feb 2009 00:45:15 -0800 (PST) In-Reply-To: <6699015.16785.1233539817447.JavaMail.root@vms063.mailsrvcs.net> References: <6699015.16785.1233539817447.JavaMail.root@vms063.mailsrvcs.net> Date: Mon, 2 Feb 2009 00:45:15 -0800 Message-ID: <7d6fde3d0902020045h55255cane0d6dd9f64d23f5@mail.gmail.com> From: Garrett Cooper To: Sergey Babkin Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: bsd.quest@googlemail.com, freebsd-hackers@freebsd.org Subject: Re: bus_dma (9). What exactly means "Loading of memory allocation" ? 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: Mon, 02 Feb 2009 08:45:20 -0000 On Sun, Feb 1, 2009 at 5:56 PM, Sergey Babkin wrote: > > If I remember correctly, loading means that the pages become mapped > and visible to the devices. Some buses can access only a limited > address space , like ISA has only a 24-bit address. When a map gets > loaded, for any pages outside of this range the temporary in-ramge > pages are allocated and the d ata gets moved through them. On some > machines, like I think DEC Alpha, the physicall addresses seen by > the devices are not the same as seen by the CPU , these need to be > translated. And so on. > I think my real old articl e had some of these explanations but now > the Daemonnews site seems to be re al slow: > http://ezine.daemonnews.org/200008/isa.html > -SB > (sorry a bout top quoting, it's the only kind the web interface of my > provider suppo rts) > Feb 1, 2009 03:38:27 PM, [1]bsd.quest@googlemail.com wrote: > > Hi, > at first the cut of text from man (9) bus_dma: > bus_dmamap_t > A machine-dependent opaque type describing an individual > mapp ing. > One map is used for each memory allocation that will b e loaded. > Maps can be reused once they have been unloaded.. . > Question: What exactly means "Loading of memory allocation" in thi s context > ? > Could anyone explain it or give me some little example wi th DMA > functions > for understanding it. Unfortunately it's bad English, so that might be where some of the confusion is stemming from. I'll send a doc's PR request after this to fix it. -Garrett