From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH v3] enable x2APIC without interrupt remapping under KVM Date: Tue, 30 Jun 2009 12:43:47 -0700 Message-ID: References: <20090629132926.GB20289@redhat.com> <20090630092623.GI20289@redhat.com> <20090630190307.GE8122@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-kernel\@vger.kernel.org" , Suresh Siddha , Sheng Yang , "kvm\@vger.kernel.org" , "avi\@redhat.com" To: Gleb Natapov Return-path: Received: from out01.mta.xmission.com ([166.70.13.231]:59367 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752859AbZF3Tnu (ORCPT ); Tue, 30 Jun 2009 15:43:50 -0400 In-Reply-To: <20090630190307.GE8122@redhat.com> (Gleb Natapov's message of "Tue\, 30 Jun 2009 22\:03\:07 +0300") Sender: kvm-owner@vger.kernel.org List-ID: Gleb Natapov writes: > Considering that interrupt remapping is fairly new feature > are you saying that hotplug (pci and cpu) on x86 is a horrible > hack on Linux? Just the current cpu hotplug path. >> It is better than nothing but it certainly is not something >> I would expect to work all of the time. >> > Because of horrible code or non-complaint ioapic implementation out > there? If later this is not a big issue for KVM. Both. And even in spec ioapics can't be made to work 100% reliably. >> Interrupt remapping is the one case where we have hardware >> that works according to spec and that works reasonably well. >> > I am sure when there was only one ioapic implementation in existence > it worked according to a spec (and if not spec was changed :)) Give > interrupt remapping some time and than we will see how above statement > holds. What we need for cpu hotplug/unplug is on the tested path now. That is a significant difference. Eric