Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755229Ab0LGKXp (ORCPT ); Tue, 7 Dec 2010 05:23:45 -0500 Received: from smtp.ctxuk.citrix.com ([62.200.22.115]:7980 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755196Ab0LGKXo (ORCPT ); Tue, 7 Dec 2010 05:23:44 -0500 X-IronPort-AV: E=Sophos;i="4.59,310,1288569600"; d="scan'208";a="3219542" Date: Tue, 7 Dec 2010 10:23:44 +0000 From: Stefano Stabellini X-X-Sender: sstabellini@kaball-desktop To: Sheng Yang CC: Jeremy Fitzhardinge , Stefano Stabellini , "konrad.wilk@oracle.com" , xen-devel , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/2] xen: HVM X2APIC support In-Reply-To: <1291708317-25103-2-git-send-email-sheng@linux.intel.com> Message-ID: References: <1291708317-25103-1-git-send-email-sheng@linux.intel.com> <1291708317-25103-2-git-send-email-sheng@linux.intel.com> User-Agent: Alpine 2.00 (DEB 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 Content-Length: 961 Lines: 26 On Tue, 7 Dec 2010, Sheng Yang wrote: > +bool xen_hvm_need_lapic(void) > +{ > + if (xen_pv_domain()) > + return false; > + if (xen_hvm_domain() && > + (xen_feature(XENFEAT_hvm_pirqs) || xen_have_vector_callback)) > + return false; > + return (xen_cpuid_base() != 0); > +} > +EXPORT_SYMBOL_GPL(xen_hvm_need_lapic); > + Why do you want to disable x2apic if (xen_have_vector_callback && !xen_feature(XENFEAT_hvm_pirqs))? In this case some emulated devices are still used, like the serial, and need interrupt delivery using an apic. Same is true for all the pci devices assigned to the VM. The only case in which the apic is basically left unused is (xen_feature(XENFEAT_hvm_pirqs) && xen_have_vector_callback). -- 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/