Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753255AbbKQPVg (ORCPT ); Tue, 17 Nov 2015 10:21:36 -0500 Received: from mail-pa0-f49.google.com ([209.85.220.49]:33688 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750835AbbKQPVf (ORCPT ); Tue, 17 Nov 2015 10:21:35 -0500 MIME-Version: 1.0 Date: Tue, 17 Nov 2015 15:21:35 +0000 Message-ID: Subject: read physical address space From: alan hopes To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 820 Lines: 24 Hi, I am new to kernel and working on a college project. I have kernel module which takes process ID. Based on the PID, I walk its page tables and get to PTE for a particular VMA area. I convert PTE to physical address (phy_addr) and now I want to read from the that physical address. I have made sure the page containing the physical address is mapped but if I do printk (*phys_addr) , then kernel crashes. I think I am missing some important concept here. Do I need another driver to access physical space, may be a PCI driver as RAM being a PCI device ? Thanks Alan -- 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/