From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031188Ab2COWey (ORCPT ); Thu, 15 Mar 2012 18:34:54 -0400 Received: from cpanel23.proisp.no ([88.87.44.74]:56931 "EHLO cpanel23.proisp.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030380Ab2COWex (ORCPT ); Thu, 15 Mar 2012 18:34:53 -0400 Message-ID: <4F626E6C.5010809@numascale.com> Date: Thu, 15 Mar 2012 23:34:20 +0100 From: Steffen Persvold User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:10.0) Gecko/20120129 Thunderbird/10.0 MIME-Version: 1.0 To: Suresh Siddha CC: Yinghai Lu , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Daniel J Blueman , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH] Use x2apic_supported() in the default_apic_id_valid() function. References: <1331834583-16070-1-git-send-email-sp@numascale.com> <1331846504.16101.12.camel@sbsiddha-desk.sc.intel.com> In-Reply-To: <1331846504.16101.12.camel@sbsiddha-desk.sc.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - cpanel23.proisp.no X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - numascale.com X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/15/12 22:21 , Suresh Siddha wrote: > On Thu, 2012-03-15 at 13:23 -0700, Yinghai Lu wrote: >> On Thu, Mar 15, 2012 at 11:03 AM, Steffen Persvold wrote: >>> Use x2apic_supported() in the default_apic_id_valid() function. If x2apic mode is disabled (via nox2apic for example), x2apic_supported() will return false. >>> >>> This allows us to substitute the check in arch/x86/kernel/acpi/boot.c::acpi_parse_x2apic and avoid feigning the x2apic cpu feature in the NumaChip apic code. >>> >>> Signed-off-by: Steffen Persvold >>> Reviewed-by: Daniel J Blueman >> >> I double checked on system with x2apic preenabled, >> nox2apic in boot command line still works well and it >> skips starting APs with apic id> 255. >> >> Acked-by: Yinghai Lu > Suresh, > This breaks the smpboot check if enabling interrupt-remapping/x2apic > fails on a platform. We will be in xapic mode and we don't clear the > x2apic cpufeature bit in this case and as such smpboot check will fail. > > So this change breaks the commit > c284b42abadbb22083bfde24d308899c08d44ffa. > I was afraid of that. > I think the right thing is to have two different apid_id_valid checks > one for xapic driver (apic_flat_64.c) and another for x2apic driver > (x2apic_phys/cluster.c) and that way, x2apic MADT entries will be parsed > only if bios has handed over the OS in x2apic mode or if we have > selected the numachip model. > Is my understanding of your suggestion correct that in x2apic_phys/cluster.c we add the following apic_id_valid() function : static int x2apic_apic_id_valid(int apicid) { return x2apic_mode || (apicid < 255); } ? Considering that this function (apic->apic_id_valid()) is called already in the acpi/boot.c::acpi_parse_x2apic() function is it sufficient enough to test for x2apic_mode ? Yinghai indicated that x2apic_mode was not set at this point, thus it was testing cpu_has_x2apic instead ? I must admit that I am not familiar enough with the APIC/ACPI code base to determine the sequence of events here (i.e MADT parsing, enabling of x2apic mode etc. etc.). Please advice. Kind regards, Steffen