From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752231AbbJKTTB (ORCPT ); Sun, 11 Oct 2015 15:19:01 -0400 Received: from www.linutronix.de ([62.245.132.108]:42009 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752075AbbJKTTA (ORCPT ); Sun, 11 Oct 2015 15:19:00 -0400 Date: Sun, 11 Oct 2015 21:18:21 +0200 (CEST) From: Thomas Gleixner To: Andy Shevchenko cc: linux-kernel@vger.kernel.org, Ingo Molnar , "H . Peter Anvin" , x86@kernel.org Subject: Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for IO In-Reply-To: <1444400949-103551-1-git-send-email-andriy.shevchenko@linux.intel.com> Message-ID: References: <1444400949-103551-1-git-send-email-andriy.shevchenko@linux.intel.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy, On Fri, 9 Oct 2015, Andy Shevchenko wrote: > #ifdef CONFIG_PCI > static void mem32_serial_out(unsigned long addr, int offset, int value) > { > - u32 *vaddr = (u32 *)addr; > + void __iomem *vaddr = (void __iomem *)addr; > /* shift implied by pointer type */ > writel(value, vaddr + offset); This is broken. Assume vaddr = 0x1000 and offset = 1 ==> u32 *vaddr = 0x1000; ==> vaddr + offset = 0x1004 with your change ==> void __iomem *vaddr = 0x1000; ==> vaddr + offset = 0x1001 This comment is there for a reason: > /* shift implied by pointer type */ Thanks, tglx