Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271420AbTHDJfl (ORCPT ); Mon, 4 Aug 2003 05:35:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271606AbTHDJfl (ORCPT ); Mon, 4 Aug 2003 05:35:41 -0400 Received: from host81-136-144-97.in-addr.btopenworld.com ([81.136.144.97]:41640 "EHLO mail.dark.lan") by vger.kernel.org with ESMTP id S271420AbTHDJfk (ORCPT ); Mon, 4 Aug 2003 05:35:40 -0400 Subject: Re: [Q] Question about memory access From: Gianni Tedesco To: "Cho, joon-woo" Cc: linux-kernel@vger.kernel.org In-Reply-To: <00a001c35a58$02c20f00$a5a5f88f@core8fyzomwjks> References: <00a001c35a58$02c20f00$a5a5f88f@core8fyzomwjks> Content-Type: text/plain Message-Id: <1059989725.392.2.camel@sherbert> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.3.92 (Preview Release) Date: 04 Aug 2003 10:35:25 +0100 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 897 Lines: 23 On Mon, 2003-08-04 at 08:14, Cho, joon-woo wrote: > If someone want to transfer large data from some device to memory, he may > use DMA method. > > At this point, i am confused. > > I think that only one process can access physical memory(RAM) at a time. The DMA controller is a dedicated piece of hardware that copies the data from devices to RAM. This means that other processes can use the CPU while the DMA is in progress. That is the whole point of DMA. -- // Gianni Tedesco (gianni at scaramanga dot co dot uk) lynx --source www.scaramanga.co.uk/gianni-at-ecsc.asc | gpg --import 8646BE7D: 6D9F 2287 870E A2C9 8F60 3A3C 91B5 7669 8646 BE7D - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/