From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752602AbbKPVj5 (ORCPT ); Mon, 16 Nov 2015 16:39:57 -0500 Received: from www.linutronix.de ([62.245.132.108]:43306 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752013AbbKPVj4 (ORCPT ); Mon, 16 Nov 2015 16:39:56 -0500 Date: Mon, 16 Nov 2015 22:39:01 +0100 (CET) From: Thomas Gleixner To: Boris Ostrovsky cc: Vitaly Kuznetsov , x86@kernel.org, Ingo Molnar , "H. Peter Anvin" , Jiang Liu , "K. Y. Srinivasan" , linux-kernel@vger.kernel.org, xen-devel Subject: Re: [PATCH v2] x86/irq: Probe for PIC presence before allocating descs for legacy IRQs In-Reply-To: <564A43F5.30602@oracle.com> Message-ID: References: <1446543614-3621-1-git-send-email-vkuznets@redhat.com> <564A43F5.30602@oracle.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 16 Nov 2015, Boris Ostrovsky wrote: > Xen expects legacy interrupts to be there (pretty much for the same reason as > Hyper-V does) and with this change arch_probe_nr_irqs() returns zero and no > descriptors are allocated. Right, because everything which has a PIT gets them and everything which does not have a PIT does not. > We can allocate those descriptors as needed in xen_irq_init() (if we know that > IRQs are legacy), although that would look somewhat ugly and out of place. Why preallocating them in xen_irq_init()? You simply can remove the NR_IRQS_LEGACY checks in xen_allocate_irq_gsi/xen_free_irq(), right? Thanks, tglx