From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45315) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Utq1S-0007UL-AG for qemu-devel@nongnu.org; Mon, 01 Jul 2013 22:08:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Utq1P-0001xz-0D for qemu-devel@nongnu.org; Mon, 01 Jul 2013 22:08:50 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:48787) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Utq1O-0001wr-QN for qemu-devel@nongnu.org; Mon, 01 Jul 2013 22:08:46 -0400 Received: by mail-pa0-f50.google.com with SMTP id fb1so5627255pad.23 for ; Mon, 01 Jul 2013 19:08:44 -0700 (PDT) Message-ID: <51D23627.5090308@ozlabs.ru> Date: Tue, 02 Jul 2013 12:08:39 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1372315560-5478-1-git-send-email-aik@ozlabs.ru> <1372315560-5478-3-git-send-email-aik@ozlabs.ru> <20130627114719.GG10614@voom.fritz.box> <51CC2D4F.9000401@ozlabs.ru> <20130702000635.GA4729@voom.fritz.box> <6A17A370-6FC7-4912-8B9E-9E51280F3BAB@suse.de> In-Reply-To: <6A17A370-6FC7-4912-8B9E-9E51280F3BAB@suse.de> Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 02/17] pseries: rework XICS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: Anthony Liguori , qemu-devel@nongnu.org, qemu-ppc@nongnu.org, Paolo Bonzini , Paul Mackerras , David Gibson On 07/02/2013 10:21 AM, Alexander Graf wrote: > > On 02.07.2013, at 02:06, David Gibson wrote: > >> On Thu, Jun 27, 2013 at 10:17:19PM +1000, Alexey Kardashevskiy wrote: >>> On 06/27/2013 09:47 PM, David Gibson wrote: >>>> On Thu, Jun 27, 2013 at 04:45:45PM +1000, Alexey Kardashevskiy wrote: >>>>> Currently XICS interrupt controller is not a QEMU device. As we are going >>>>> to support in-kernel emulated XICS which is a part of KVM, it make >>>>> sense not to extend the existing XICS and have multiple KVM stub functions >>>>> but to create yet another device and share pieces between fully emulated >>>>> XICS and in-kernel XICS. >>>> >>>> Hmm. So, I think changing the xics to the qdev/qom framework is a >>>> generally good idea. But I'm not convinced its a good idea to have >>>> different devices for the kernel and non-kernel xics. >>> >>> The idea came from Alex Graf, this is already done for openpic/openpic-kvm. >>> The normal practice is to move ioctls to KVM to KVM code and provide empty >>> stubs for non-KVM case. There were too many so having a separate xics-kvm >>> is kind of help. >>> >>> >>>> Won't that >>>> prevent migrating from a system with a kernel xics to one without, or >>>> vice versa? >>> >>> Mmm. Do we care much about that?... >> >> Enough to avoid making it impossible by design. > > We went that route with x86 too after lots of hassle trying to shoehorn the in-kernel APIC into the emulation device. It's more hassle than gain. At the moment it can be supported at no cost so next time I'll post it with matched vmsd. >>> At the moment it is not supported that as VMStateDescription have different >>> .name for xics and xics-kvm but easy to fix. And we do not pass a device to >>> vmstate_register so that must be it. >> >> Ok, if you can make the ids in the vmsd match, then that should be ok. > > I really just wouldn't bother too much about it. Sooner or later QEMU-XICS is going to be a legacy and debug only option. -- Alexey