From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933114AbXEGLjJ (ORCPT ); Mon, 7 May 2007 07:39:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932997AbXEGLjJ (ORCPT ); Mon, 7 May 2007 07:39:09 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:52207 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933114AbXEGLjI (ORCPT ); Mon, 7 May 2007 07:39:08 -0400 Date: Mon, 7 May 2007 17:08:54 +0530 From: Vivek Goyal To: linux kernel mailing list Cc: Morton Andrew Morton , Andi Kleen , "Eric W. Biederman" Subject: [PATCH] x86_64: Display more intutive error message if kernel is not 2MB aligned Message-ID: <20070507113854.GA4899@in.ibm.com> Reply-To: vgoyal@in.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org o x86_64 kernel needs to be compiled for 2MB aligned addresses. Currently we are using BUILD_BUG_ON() to warn the user if he has not done so. But looks like folks are not finding message very intutive and don't open the respective c file to find problem source. (Bug 8439) arch/x86_64/kernel/head64.c: In function 'x86_64_start_kernel': arch/x86_64/kernel/head64.c:70: error: size of array 'type name' is negative o Using preprocessor directive #error to print a better message if CONFIG_PHYSICAL_START is not aligned to 2MB boundary. Signed-off-by: Vivek Goyal --- linux-2.6.21-rc7-mm2-root/arch/x86_64/kernel/head64.c | 7 ------- linux-2.6.21-rc7-mm2-root/include/asm-x86_64/page.h | 9 +++++++++ 2 files changed, 9 insertions(+), 7 deletions(-) diff -puN arch/x86_64/kernel/head64.c~x86_64-warn-if-kernel-is-not-2MB-aligned arch/x86_64/kernel/head64.c --- linux-2.6.21-rc7-mm2/arch/x86_64/kernel/head64.c~x86_64-warn-if-kernel-is-not-2MB-aligned 2007-05-07 16:17:21.000000000 +0530 +++ linux-2.6.21-rc7-mm2-root/arch/x86_64/kernel/head64.c 2007-05-07 16:25:42.000000000 +0530 @@ -62,13 +62,6 @@ void __init x86_64_start_kernel(char * r { int i; - /* - * Make sure kernel is aligned to 2MB address. Catching it at compile - * time is better. Change your config file and compile the kernel - * for a 2MB aligned address (CONFIG_PHYSICAL_START) - */ - BUILD_BUG_ON(CONFIG_PHYSICAL_START & (__KERNEL_ALIGN - 1)); - /* clear bss before set_intr_gate with early_idt_handler */ clear_bss(); diff -puN include/asm-x86_64/page.h~x86_64-warn-if-kernel-is-not-2MB-aligned include/asm-x86_64/page.h --- linux-2.6.21-rc7-mm2/include/asm-x86_64/page.h~x86_64-warn-if-kernel-is-not-2MB-aligned 2007-05-07 16:24:16.000000000 +0530 +++ linux-2.6.21-rc7-mm2-root/include/asm-x86_64/page.h 2007-05-07 16:25:29.000000000 +0530 @@ -80,6 +80,15 @@ extern unsigned long phys_base; #define __PHYSICAL_START CONFIG_PHYSICAL_START #define __KERNEL_ALIGN 0x200000 +/* + * Make sure kernel is aligned to 2MB address. Catching it at compile + * time is better. Change your config file and compile the kernel + * for a 2MB aligned address (CONFIG_PHYSICAL_START) + */ +#if (CONFIG_PHYSICAL_START % __KERNEL_ALIGN) != 0 +#error "CONFIG_PHYSICAL_START must be a multiple of 2MB" +#endif + #define __START_KERNEL (__START_KERNEL_map + __PHYSICAL_START) #define __START_KERNEL_map 0xffffffff80000000 #define __PAGE_OFFSET 0xffff810000000000 _