From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44938) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WYGCk-0008Se-AN for qemu-devel@nongnu.org; Thu, 10 Apr 2014 10:43:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WYGCV-000585-MG for qemu-devel@nongnu.org; Thu, 10 Apr 2014 10:43:50 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:58861) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WYGCV-00057p-GD for qemu-devel@nongnu.org; Thu, 10 Apr 2014 10:43:35 -0400 Received: by mail-pd0-f180.google.com with SMTP id v10so3960721pde.39 for ; Thu, 10 Apr 2014 07:43:34 -0700 (PDT) Message-ID: <5346AE11.1050206@ozlabs.ru> Date: Fri, 11 Apr 2014 00:43:29 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1394770689-29039-1-git-send-email-aik@ozlabs.ru> <1394770689-29039-7-git-send-email-aik@ozlabs.ru> <534693E4.1050204@suse.de> <53469B86.7020400@ozlabs.ru> <53469BF3.7000406@suse.de> In-Reply-To: <53469BF3.7000406@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 6/8] spapr: move interrupt allocator to xics List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf , qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= On 04/10/2014 11:26 PM, Alexander Graf wrote: > > On 10.04.14 15:24, Alexey Kardashevskiy wrote: >> On 04/10/2014 10:51 PM, Alexander Graf wrote: >>> On 14.03.14 05:18, Alexey Kardashevskiy wrote: >>>> The current allocator returns IRQ numbers from a pool and does not >>>> support IRQs reuse in any form as it did not keep track of what it >>>> previously returned, it only had the last returned IRQ. >>>> However migration may change interrupts for devices depending on >>>> their order in the command line. >>> Wtf? Nonono, this sounds very bogus and wrong. Migration shouldn't change >>> anything. >> >> I put wrong commit message. By change I meant that the default state before >> the destination guest started accepting migration is different from what >> the destination guest became after migration finished. And migration cannot >> avoid changing this default state. > > Ok, why is the IRQ configuration different? Because QEMU creates devices in the order as in the command line, and libvirt changes this order - the XML used to create the guest and the XML which is sends during migration are different. libvirt thinks it is ok while it keeps @reg property for (for example) spapr-vscsi devices but it is not because since the order is different, devices call IRQ allocator in different order and get different IRQs. -- Alexey