Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964821AbcDLNXu (ORCPT ); Tue, 12 Apr 2016 09:23:50 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:38254 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964790AbcDLNXt (ORCPT ); Tue, 12 Apr 2016 09:23:49 -0400 Subject: Re: Xen regression, Was: [PATCH] x86/irq: Probe for PIC presence before allocating descs for legacy IRQs To: Stefano Stabellini , Vitaly Kuznetsov References: <1446470676-1877-1-git-send-email-vkuznets@redhat.com> Cc: x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jiang Liu , "K. Y. Srinivasan" , linux-kernel@vger.kernel.org, konrad.wilk@oracle.com, david.vrabel@citrix.com, jgross@suse.com From: Boris Ostrovsky Message-ID: <570CF69A.1020701@oracle.com> Date: Tue, 12 Apr 2016 09:22:34 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 751 Lines: 22 On 04/11/2016 10:08 PM, Stefano Stabellini wrote: > Hi all, > > Unfortunately this patch (now commit > 8c058b0b9c34d8c8d7912880956543769323e2d8) causes a regression on Xen > when running on top of QEMU: the number of PIT irqs get set to 0 by > probe_8259A but actually there are 16. > > Any suggestions on how to fix this? > > 1) we could revert 8c058b0b9c34d8c8d7912880956543769323e2d8 > 2) we could introduce an 'if (!xen_domain())' in probe_8259A > 3) suggestions welcome Stefano, do you have b4ff8389ed14b849354b59ce9b360bdefcdbf99c ? It was supposed to fix this problem for Xen. However, I just noticed that arch/arm64/include/asm/irq.h makes nr_legacy_irqs() return 0 (unlike arch/arm/include/asm/irq.h). Could that be the problem? -boris