Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761186AbXEQEw0 (ORCPT ); Thu, 17 May 2007 00:52:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755726AbXEQEwT (ORCPT ); Thu, 17 May 2007 00:52:19 -0400 Received: from terminus.zytor.com ([192.83.249.54]:37606 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755531AbXEQEwT (ORCPT ); Thu, 17 May 2007 00:52:19 -0400 Message-ID: <464BDF58.2090907@zytor.com> Date: Wed, 16 May 2007 21:51:36 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.0 (X11/20070419) MIME-Version: 1.0 To: Linus Torvalds CC: Christian , linux-kernel@vger.kernel.org Subject: Re: 2.6.22-rc1 does not boot on VIA C3_2 cause of X86_CMPXCHG64 References: <464B9D2C.7040704@cv-sv.de> <464BAF07.9020003@cv-sv.de> <464BC67F.7080707@zytor.com> In-Reply-To: X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1183 Lines: 29 Linus Torvalds wrote: > > On Wed, 16 May 2007, H. Peter Anvin wrote: >> It gets turned on by the code in arch/i386/kernel/cpu. It's just that >> the new code that Andi added runs during setup, i.e. in real mode, so >> *way* earlier than that. > > Ahh. Do we really need it that early? The reason to do it early is so that we can still get a message out if the CPU doesn't have the necessary features. This is generic code and not specific to CX8. Since I'm rewriting the setup code in C, I have added code to enable features on VIA and Transmeta CPUs (there was already code in there to enable features on AMD; Intel isn't known to hide any features other than PAE on 400 MHz FSB Pentium-M.) I think the early feature detection makes good sense. It's a heckuva lot nicer to get a message on your screen saying that you can't boot this kernel on this CPU than a crash, or an early_printk which may never actually get to you. -hpa - 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/