Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755982AbYHNKgs (ORCPT ); Thu, 14 Aug 2008 06:36:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752150AbYHNKgh (ORCPT ); Thu, 14 Aug 2008 06:36:37 -0400 Received: from mail-gx0-f16.google.com ([209.85.217.16]:33597 "EHLO mail-gx0-f16.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752009AbYHNKgg (ORCPT ); Thu, 14 Aug 2008 06:36:36 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=FfBk35c0+ghm5AqQ7WnwyQ9IBJFk2soEL0jGSzd+YWGGKB8Z2VvOJ44G9puvKfAINA gcflwiqdLQxR8m8IXIsUOanZ2FIZUIiCY05mu/WLV2WDWhmR/sUeaRGwX4CZpO+UC0pr zNZe9t9gq0QXJscESmivX5f6HagVJDZ993TRI= Message-ID: <86802c440808140336k3558dfbew308ac7d7bdb23c@mail.gmail.com> Date: Thu, 14 Aug 2008 03:36:35 -0700 From: "Yinghai Lu" To: "Bill Fink" Subject: Re: HPET regression in 2.6.26 versus 2.6.25 -- revert for 2.6.26-rc1 failed Cc: "David Witbrodt" , linux-kernel@vger.kernel.org, "Ingo Molnar" , "Paul E. McKenney" , "Peter Zijlstra" , "Thomas Gleixner" , "H. Peter Anvin" , netdev In-Reply-To: <20080814060433.684c4fe5.billfink@mindspring.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <737832.54450.qm@web82101.mail.mud.yahoo.com> <20080814060433.684c4fe5.billfink@mindspring.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3087 Lines: 88 On Thu, Aug 14, 2008 at 3:04 AM, Bill Fink wrote: > Hi David, > > On Wed, 13 Aug 2008, David Witbrodt wrote: > >> [Yinghai, please note that I did not request a patch to revert the >> problem commit. I was merely experimenting -- on my own time, so >> you folks would not have to bother -- to see if I could make it >> work. I should have made that more clear! Having said that, I am >> glad to test changes of any kind on my machine: reverts, code for >> debugging or info, experiments, etc.] > > I'm not sure Yinghai's revert patch is completely equivalent to > a revert of the original problematic commit, by a side-by-side > comparison of the original commit with his recent revert patch, > but then I don't really know that code at all. > > In the original code there was a section (in e820_reserve_resources()): > > #ifdef CONFIG_KEXEC > if (crashk_res.start != crashk_res.end) > request_resource(res, &crashk_res); > #endif > > If you don't have CONFIG_KEXEC defined in your .config, which is > probably the case, then you would never request a crashk_res resource. > But in the code after the original commit, it unconditionally calls > (in reserve_crashkernel()): > > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > insert_resource(&iomem_resource, &crashk_res); > > And after Yinghai's revert patch it still does (in reserve_crashkernel()): > > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > crashk_res_ptr = &crashk_res; > > and (in setup_arch()): > > num_res = 3; > if (crashk_res_ptr) { > res_kernel[num_res] = crashk_res_ptr; > num_res++; > } > e820_reserve_resources(res_kernel, num_res); > > then (in e820_reserve_resources()): > > for (j = 0; j < nr_res_k; j++) { > if (!res_kernel[j]) > continue; > request_resource(res, res_kernel[j]); > } > > which for j == 3 is: > > request_resource(res, &crashk_res); > > Now it would appear that the new: > > insert_resource(&iomem_resource, &crashk_res); > > or new: > > request_resource(res, &crashk_res); > > should be noops. But if for any reason crash_size is not zero, > then there could be a difference. I have no idea if this is at all > significant, but I thought I'd point it out just in case. why oops ? if not valid crash kernel size etc is input, crashk_res_ptr will be null > if (crashk_res_ptr) { > res_kernel[num_res] = crashk_res_ptr; > num_res++; > } it that is not appended to res_kernel... YH -- 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/