From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751690AbZGLGcH (ORCPT ); Sun, 12 Jul 2009 02:32:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751240AbZGLGbz (ORCPT ); Sun, 12 Jul 2009 02:31:55 -0400 Received: from eddie.linux-mips.org ([78.24.191.182]:50490 "EHLO eddie.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751173AbZGLGbz (ORCPT ); Sun, 12 Jul 2009 02:31:55 -0400 Date: Sun, 12 Jul 2009 07:31:44 +0100 (BST) From: "Maciej W. Rozycki" To: Cyrill Gorcunov cc: Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Yinghai Lu , LKML Subject: Re: [RFC -tip] x86,apic - set cpu_has_apic for discrete apic In-Reply-To: <20090712055200.GB4782@lenovo> Message-ID: References: <20090711212929.GG5325@lenovo> <20090712055200.GB4782@lenovo> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 12 Jul 2009, Cyrill Gorcunov wrote: > Well, I've been using code reading. No real hardware test. > I just don't have such a hardware. Then simulate it! Proofreading is not enough -- the APIC code is too twisted. Be imaginative -- for example you can clear the APIC bit at the time CPUID flags are saved for later use with cpu_has_apic() and see if the code behaves as expected. Sprinkle printk()s here and there to see if variables are set correctly, whether the right code paths are taken, etc. Tedious? Well, who said kernel debugging was going to be a piece of cake? Most of the APIC support code I have written has been run-time tested like this -- one change at a time. Do you think I have an infinite number of SMP configurations too? All the clean-ups I worked on last year were tested with one laptop. I didn't even have a serial port for console dumps back then. NAK from me until you've tested it, sorry. Maciej