From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58ED4C04AB4 for ; Tue, 14 May 2019 08:50:40 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2CC162085A for ; Tue, 14 May 2019 08:50:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2CC162085A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:42990 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hQT8x-0003NO-7B for qemu-devel@archiver.kernel.org; Tue, 14 May 2019 04:50:39 -0400 Received: from eggs.gnu.org ([209.51.188.92]:51988) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hQT89-0002xi-5k for qemu-devel@nongnu.org; Tue, 14 May 2019 04:49:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hQT87-0005Ep-9M for qemu-devel@nongnu.org; Tue, 14 May 2019 04:49:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52416) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hQT86-00053h-Uz; Tue, 14 May 2019 04:49:47 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 557ECA96EA; Tue, 14 May 2019 08:49:43 +0000 (UTC) Received: from gondolin (dhcp-192-222.str.redhat.com [10.33.192.222]) by smtp.corp.redhat.com (Postfix) with ESMTP id 063325D720; Tue, 14 May 2019 08:49:36 +0000 (UTC) Date: Tue, 14 May 2019 10:49:34 +0200 From: Cornelia Huck To: Christian Borntraeger Message-ID: <20190514104934.6bba9232.cohuck@redhat.com> In-Reply-To: <066c7470-94a3-a922-9a12-1ca42e474c51@de.ibm.com> References: <1556749903-19221-1-git-send-email-walling@linux.ibm.com> <09293a1c-d000-83a8-46b8-b97ad4fa9774@de.ibm.com> <56e3ace1-6e48-0e20-47d5-b07ac6dfcf31@redhat.com> <20190513134637.3d8bb275.cohuck@redhat.com> <898144e3-615e-5074-fb68-bf9995c64609@de.ibm.com> <155d2ca3-6a48-c99a-fe42-dca8e3fd4344@redhat.com> <066c7470-94a3-a922-9a12-1ca42e474c51@de.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 14 May 2019 08:49:43 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v4] s390: diagnose 318 info reset and migration support X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Collin Walling , David Hildenbrand , mst@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, qemu-s390x@nongnu.org, pbonzini@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 14 May 2019 10:37:32 +0200 Christian Borntraeger wrote: > On 14.05.19 09:28, David Hildenbrand wrote: > >>>> But that can be tested using the runability information if I am not wrong. > >>> > >>> You mean the cpu level information, right? > > > > Yes, query-cpu-definition includes for each model runability information > > via "unavailable-features" (valid under the started QEMU machine). > > > >>> > >>>> > >>>>> and others that we have today. > >>>>> > >>>>> So yes, I think this would be acceptable. > >>>> > >>>> I guess it is acceptable yes. I doubt anybody uses that many CPUs in > >>>> production either way. But you never know. > >>> > >>> I think that using that many cpus is a more uncommon setup, but I still > >>> think that having to wait for actual failure > >> > >> That can happen all the time today. You can easily say z14 in the xml when > >> on a zEC12. Only at startup you get the error. The question is really: > > > > "-smp 248 -cpu host" will no longer work, while e.g. "-smp 248 -cpu z12" > > will work. Actually, even "-smp 248" will no longer work on affected > > machines. > > > > That is why wonder if it is better to disable the feature and print a > > warning. Similar to CMMA, where want want to tolerate when CMMA is not > > possible in the current environment (huge pages). > > > > "Diag318 will not be enabled because it is not compatible with more than > > 240 CPUs". > > > > However, I still think that implementing support for more than one SCLP > > response page is the best solution. Guests will need adaptions for > 240 > > CPUs with Diag318, but who cares? Existing setups will continue to work. > > > > Implementing that SCLP thingy will avoid any warnings and any errors. It > > just works from the QEMU perspective. > > > > Is implementing this realistic? > > Yes it is but it will take time. I will try to get this rolling. To make > progress on the diag318 thing, can we error on startup now and simply > remove that check when when have implemented a larger sccb? If we would > now do all kinds of "change the max number games" would be harder to "fix". So, the idea right now is: - fail to start if you try to specify a diag318 device and more than 240 cpus (do we need a knob to turn off the device?) - in the future, support more than one SCLP response page I'm getting a bit lost in the discussion; but the above sounds reasonable to me.