From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 8 Jun 2001 09:51:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 8 Jun 2001 09:50:55 -0400 Received: from f220.law11.hotmail.com ([64.4.17.220]:4870 "EHLO hotmail.com") by vger.kernel.org with ESMTP id ; Fri, 8 Jun 2001 09:50:44 -0400 X-Originating-IP: [165.21.83.232] From: "Louis Lam" To: linux-kernel@vger.kernel.org Subject: Question on Loop and PPDD devices Date: Fri, 08 Jun 2001 21:50:38 +0800 Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: X-OriginalArrivalTime: 08 Jun 2001 13:50:38.0556 (UTC) FILETIME=[FFFA61C0:01C0F021] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, I'm quite new to kernel development, please advice.... Got some questions about Loop and PPDD Devices. *For 2.2 kernels, there are loop-specific modifications in ll_rw_block.c, in make_request(), where the max_req is divided by two. Comments read: loop uses two requests, 1 for loop and the other for real device. Q1. How is it exactly using two requests? Q2. Requests are made to the loop device and when will it generate another request to the real device? Q3. Does the loop device have its own request queue? Or is it using the same request queue as the actual device it is associated with? Q4. What is the relationship between loop device driver and the actual disc driver? How/When is data actually written/read from the disk? Q4. Where can I gather more information on the principles behind the how loop devices work? Any particular person who might be able to help? *I'm Using ppdd to encrypt my swap data, it is very similar to the loop device. Currently as suggested by the instructions, I'm using a swap file in an encrypted partition. I'm trying to port it to the 2.2.14-5.0(Redhat 6.2 Kernel)and noticed that when I try to run something like "make -j 3" , there are errors in decryption. This did not happen on a standard 2.2.13 kernel. Sometimes it deadlocks as well(quite intermittent, but usually when I just changed the swap space to the encrypted file). Q6: What should I be looking for in order to port it to that kernel? Understand there are changes to buffer.c and various other files related to block I/O, and possibly some to memory management as well. PS.. I'm currently not subscribed to this mailing list, please send replies directly to my email address. Thank You in Advance, Louis Lam lsauchun@hotmail.com sclam@singnet.com.sg _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.