From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 18 Feb 2003 22:01:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 18 Feb 2003 22:01:01 -0500 Received: from f156.pav2.hotmail.com ([64.4.37.156]:64775 "EHLO hotmail.com") by vger.kernel.org with ESMTP id ; Tue, 18 Feb 2003 22:00:26 -0500 X-Originating-IP: [129.219.25.77] From: "shesha bhushan" To: linux-kernel@vger.kernel.org Subject: What does pci_map_single do Date: Wed, 19 Feb 2003 03:10:23 +0000 Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: X-OriginalArrivalTime: 19 Feb 2003 03:10:23.0422 (UTC) FILETIME=[714CDDE0:01C2D7C4] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi All, I wanted to use DMA in my device driver. 1. pci_map_single will transfer the data from RAM (kernel area) to the hardware accessible area and will provide with a pointer which can then be passed to the hardware. 2. In the above function the "size" parameter indicates the amount of DMA transfer. Am I correct in the above two points? If I am wrong please correct me. In the Linux Device driver book (page 408), he says, data must be explicitly flushed from the processor cache. And data flushed this way is not avaliable to the device. This means that we must flush the processor cache before calling pci_map_single. How can we achieve this. Thanking You Shesha _________________________________________________________________ The new MSN 8: advanced junk mail protection and 2 months FREE* http://join.msn.com/?page=features/junkmail