From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:41428) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RyRCT-0000bJ-Ih for qemu-devel@nongnu.org; Fri, 17 Feb 2012 12:02:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RyRCP-0004vh-4Q for qemu-devel@nongnu.org; Fri, 17 Feb 2012 12:02:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:7199) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RyRCO-0004vZ-LL for qemu-devel@nongnu.org; Fri, 17 Feb 2012 12:02:21 -0500 Message-ID: <4F3E8817.7050001@redhat.com> Date: Fri, 17 Feb 2012 18:02:15 +0100 From: Igor Mammedov MIME-Version: 1.0 References: <1329347774-23262-1-git-send-email-imammedo@redhat.com> <1329347774-23262-2-git-send-email-imammedo@redhat.com> <4F3CE7A5.30600@siemens.com> <4F3CF9AE.5020701@codemonkey.ws> In-Reply-To: <4F3CF9AE.5020701@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/7] Introduce a new bus "ICC" to connect APIC List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Jan Kiszka , "qemu-devel@nongnu.org" , "gleb@redhat.com" On 02/16/2012 01:42 PM, Anthony Liguori wrote: > On 02/16/2012 05:25 AM, Jan Kiszka wrote: >> On 2012-02-16 00:16, Igor Mammedov wrote: >>> Introduce a new structure CPUS as the controller of ICC (INTERRUPT >>> CONTROLLER COMMUNICATIONS), and new bus "ICC" to hold APIC,instead >>> of sysbus. So we can support APIC hot-plug feature. >>> >>> This is repost of original patch for qemu-kvm rebased on current qemu: >>> http://lists.nongnu.org/archive/html/qemu-devel/2011-11/msg01478.html >>> All credits to Liu Ping Fan for writing it. >>> >>> V2 changes: >>> - cpusockets_init: cpu_sockets is not yet initialized, use cpus that >>> we got as input param instead for qbus_create, this makes cpus >>> apics visible in "info qtree" monitor command >>> - fix format error spotted by Jan and missed by checkpatch >>> - cpu_has_apic_feature: return bool instead of int >>> >> >> This patch surely no longer applies. And the ICC requires QOM conversion. > > Also, post-QOM, I don't think having an ICC bus makes a whole lot of sense. > > The LAPIC can be made a child of the CPU device with a bidirectional link. > > I would simply create a fixed set of CPU links<> hung off of /devices somewhere and use that as the hotplug mechanism. This matches well the way we > model this to the guest (we expose a fixed number of pluggable sockets). I've just QOM-ified it, but in light of what you just said it may be ignored. ICC bus was used on pre Pentium 4 smp systems. And whole thing with introducing it was to provide hot-plugable bus for cpus, since hot-plug on sysbus is disabled and people argued that sysbus shouldn't be hot-plugable. However it depends on what we choose to model, we can use pre P4 ICC bus for inter-apic/ioapic communications or use P4 model allowing hot-plug on sysbus and use it for inter-apic/ioapic communications if needed. So I'd rather drop ICC patch and try your approach with CPU links<>, I see no point in introducing new bus providing we have an alternative model and existing bus for the task. > > Regards, > > Anthony Liguori > >> >> Jan >> > > -- Thanks, Igor