From owner-freebsd-hackers@FreeBSD.ORG Mon Feb 2 02:57:01 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 421091065670 for ; Mon, 2 Feb 2009 02:57:01 +0000 (UTC) (envelope-from babkin@verizon.net) Received: from vms173007pub.verizon.net (vms173007pub.verizon.net [206.46.173.7]) by mx1.freebsd.org (Postfix) with ESMTP id 21F198FC16 for ; Mon, 2 Feb 2009 02:57:01 +0000 (UTC) (envelope-from babkin@verizon.net) Received: from vms063.mailsrvcs.net ([172.18.12.132]) by vms173007.mailsrvcs.net (Sun Java(tm) System Messaging Server 6.3-2.01 (built Jun 13 2007; 32bit)) with ESMTPA id <0KEF000X21CBP7G2@vms173007.mailsrvcs.net> for freebsd-hackers@freebsd.org; Sun, 01 Feb 2009 19:55:23 -0600 (CST) Received: from 96.234.43.209 ([96.234.43.209]) by vms063.mailsrvcs.net (Verizon Webmail) with HTTP; Sun, 01 Feb 2009 19:56:57 -0600 (CST) Date: Sun, 01 Feb 2009 19:56:57 -0600 (CST) From: Sergey Babkin To: bsd.quest@googlemail.com Message-id: <6699015.16785.1233539817447.JavaMail.root@vms063.mailsrvcs.net> Content-transfer-encoding: quoted-printable X-Originating-IP: [96.234.43.209] X-Mailman-Approved-At: Mon, 02 Feb 2009 03:48:26 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: 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 02:57:01 -0000 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. References 1. 3D"mailto:bsd.quest@googlemail=