Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753153AbXABLG4 (ORCPT ); Tue, 2 Jan 2007 06:06:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754805AbXABLG4 (ORCPT ); Tue, 2 Jan 2007 06:06:56 -0500 Received: from smtpq3.tilbu1.nb.home.nl ([213.51.146.202]:55780 "EHLO smtpq3.tilbu1.nb.home.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753153AbXABLGz (ORCPT ); Tue, 2 Jan 2007 06:06:55 -0500 Message-ID: <459A3C6E.7060503@gmail.com> Date: Tue, 02 Jan 2007 12:05:18 +0100 From: Rene Herman User-Agent: Thunderbird 1.5.0.9 (X11/20061206) MIME-Version: 1.0 To: Vivek Goyal CC: Andi Kleen , Linus Torvalds , Linux Kernel Subject: CONFIG_PHYSICAL_ALIGN limited to 4M? Content-Type: multipart/mixed; boundary="------------060201010809000800010100" X-AtHome-MailScanner-Information: Please contact support@home.nl for more information X-AtHome-MailScanner: Found to be clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2136 Lines: 56 This is a multi-part message in MIME format. --------------060201010809000800010100 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Good day. A while ago it was remarked on list here that keeping the kernel 4M aligned physically might be a performance win if the added 1M (it normally loads at 1M) meant it would fit on one 4M aligned hugepage instead of 2 and since that time I've been doing such. In fact, while I was at it, I ran the kernel at 16M; while admittedly a bit of a non-issue, having never experienced ZONE_DMA shortage, I am an ISA user on a >16M machine so this seemed to make sense -- no kernel eating up "precious" ISA-DMAable memory. Recently CONFIG_PHYSICAL_START was replaced by CONFIG_PHYSICAL_ALIGN (commit e69f202d0a1419219198566e1c22218a5c71a9a6) and while 4M alignment is still possible, that's also the strictest alignment allowed meaning I can't load my (non-relocatable) kernel at 16M anymore. If I just apply the following and set it to 16M, things seem to be working for me. Was there an important reason to limit the alignment to 4M, and if so, even on non relocatable kernels? Rene. --------------060201010809000800010100 Content-Type: text/plain; name="config_physical_align_16m.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="config_physical_align_16m.diff" diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index 0d67a0a..aeadec2 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -793,7 +793,7 @@ config RELOCATABLE config PHYSICAL_ALIGN hex "Alignment value to which kernel should be aligned" default "0x100000" - range 0x2000 0x400000 + range 0x2000 0x1000000 help This value puts the alignment restrictions on physical address where kernel is loaded and run from. Kernel is compiled for an --------------060201010809000800010100-- - 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/