From mboxrd@z Thu Jan 1 00:00:00 1970 From: OGAWA Hirofumi Subject: Re: nmi is broken? Date: Wed, 04 May 2011 01:57:27 +0900 Message-ID: <87bozjlo20.fsf@devron.myhome.or.jp> References: <87sjtbe7fz.fsf@devron.myhome.or.jp> <877hak1t1s.fsf@devron.myhome.or.jp> <4DB3C6D3.9040703@redhat.com> <4DB41696.6060606@web.de> <4DB7DA11.8040503@redhat.com> <871v0njhab.fsf@devron.myhome.or.jp> <4DB93A6D.3010703@redhat.com> <87sjt2ij8b.fsf@devron.myhome.or.jp> <87k4eeihdu.fsf@devron.myhome.or.jp> <87mxj7urb0.fsf@devron.myhome.or.jp> <4DBE6F6B.6090103@redhat.com> <8739kxgoo0.fsf@devron.myhome.or.jp> <4DBFCC81.9080401@redhat.com> <4DBFD3F5.8020406@redhat.com> <87hb9blxvt.fsf@devron.myhome.or.jp> <4DC004B6.3030503@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Jan Kiszka , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail.parknet.co.jp ([210.171.160.6]:42775 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753912Ab1ECQ5b (ORCPT ); Tue, 3 May 2011 12:57:31 -0400 In-Reply-To: <4DC004B6.3030503@redhat.com> (Avi Kivity's message of "Tue, 03 May 2011 16:35:50 +0300") Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity writes: >> >> The issue with live migration is that we can't change the running >> >> configuration while the system is running, like adding the IMCR or >> >> changing the wiring. The hardware will be programmed for the old >> >> configuration and will likely fail with the new one. For example, the >> >> current wiring has the PIT output wired to PIC IRQ0 and IOAPIC INTI0; >> >> we need to change it to IOAPIC INTI2 instead. >> >> >> > >> > btw, I believe that the configuration currently implemented is legal >> > (it's similar to config 7 in table 5-2 of the mpspec); the only problem >> > is that it can't support the NMI watchdog through the I/O APIC trick, >> > yet we allow it through a hack. >> >> I'm confused a bit. "config 7 in table 5-2" says PIT output wired to >> IOAPIC INTIN2. So, we don't need to change it? > > We're like config 7 in that the 8259A output isn't wired to the IOAPIC. > However we're unlike config 7 in that the PIT output is wired to IOAPIC > INTIN0. I think we can keep it that way. > >> > Something we can do is connect the 8259A output to the I/O APIC INTIN2; >> > it should be masked so live migration will continue to work. We just >> > have to make sure that the guest is able to find that it is >> > connected there. >> >> 8259A INTR to IOAPIC INTIN2 sounds strange. Isn't it IOAPIC INTIN0? > > Usually yes, but we already have the PIT wired to INTIN0. I saw that > the kernel consults the mptable to see which pin to use, so with the > right BIOS magic we can get things to work. Um..., I'm confused more. If so, MADT doesn't say it. MADT says irq == 0 is pin == 2, this is one of reasons why linux is quite silent in check_timer(). And I can't see why it is working by pin == 2 for IOAPIC. If I can make time, I'll see what happens by pin == 2 and pin == 0 of IOAPIC in kvm. Thanks. -- OGAWA Hirofumi