Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271401AbTHDHSZ (ORCPT ); Mon, 4 Aug 2003 03:18:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271408AbTHDHSZ (ORCPT ); Mon, 4 Aug 2003 03:18:25 -0400 Received: from core.kaist.ac.kr ([143.248.147.118]:2995 "EHLO core.kaist.ac.kr") by vger.kernel.org with ESMTP id S271401AbTHDHSY (ORCPT ); Mon, 4 Aug 2003 03:18:24 -0400 Message-ID: <00a001c35a58$02c20f00$a5a5f88f@core8fyzomwjks> From: "Cho, joon-woo" To: Subject: [Q] Question about memory access Date: Mon, 4 Aug 2003 16:14:14 +0900 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1016 Lines: 39 Hello. I am highly curious about memory access problem. Maybe this is not exactly 'kernel' development problem, but I think this is highly related to 'kernel'. Anyway my question is below. 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. During DMA data transferring(This may need long time), how can other physical memory access occurs? I think that this is solved by time-sharing, process switching, or etc. Is it true? Please say abstract mechanism or kernel code location about this problem. My english is poor, so question meaning may be confused. I am sorry about this. Please answer my question. Thanks! - 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/