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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 B2E59C00523 for ; Wed, 8 Jan 2020 09:48:39 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7F72C206DA for ; Wed, 8 Jan 2020 09:48:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CnazWr57" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F72C206DA 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 ([::1]:41180 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ip7x8-00045P-Lh for qemu-devel@archiver.kernel.org; Wed, 08 Jan 2020 04:48:38 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:49564) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ip7wH-0003ZE-PW for qemu-devel@nongnu.org; Wed, 08 Jan 2020 04:47:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ip7wF-0007C9-QH for qemu-devel@nongnu.org; Wed, 08 Jan 2020 04:47:44 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:54070 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ip7wD-0007Av-Vp for qemu-devel@nongnu.org; Wed, 08 Jan 2020 04:47:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578476860; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Mx4ZvzSk+Nefx14K2LQ13Rj1gZT1s/euld6djsG8w+w=; b=CnazWr57A/PGZa+W9CwWOeg+5PuQsJk/uknLtEeHHbntR7E4HOMn2qpXwwl9VyS3rIEPaN blAduZ+fGPLT0aZovL+4JiTSppFckN78ELBp0/Q7NMuWlrgtvURsI2D1M+Z4wl3qT3BDYo UPhFCehkNjO+Rwfd8wNlGf05+BatcJY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-79-HbH4RQCmPZmWRXxW8r4_cQ-1; Wed, 08 Jan 2020 04:47:38 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9CA43800D50; Wed, 8 Jan 2020 09:47:37 +0000 (UTC) Received: from dhcp-200-226.str.redhat.com (dhcp-200-226.str.redhat.com [10.33.200.226]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D26EF100164D; Wed, 8 Jan 2020 09:47:25 +0000 (UTC) Date: Wed, 8 Jan 2020 10:47:24 +0100 From: Kevin Wolf To: Christophe de Dinechin Subject: Re: Priority of -accel (was: [PATCH] tests/qemu-iotests: Update tests to recent desugarized -accel option) Message-ID: <20200108094724.GB5057@dhcp-200-226.str.redhat.com> References: <20200106130951.29873-1-philmd@redhat.com> <12334054-4ae7-e580-9727-2d322bfa2bda@redhat.com> <1A5859EA-4403-4921-B527-DFD07C59C702@redhat.com> <360fa010-ba80-b02b-3a35-19c2b48a462d@redhat.com> <5FB9F11E-77DC-4FD6-B780-AB508DD42B42@redhat.com> MIME-Version: 1.0 In-Reply-To: <5FB9F11E-77DC-4FD6-B780-AB508DD42B42@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: HbH4RQCmPZmWRXxW8r4_cQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Daniel Berrange , qemu-block@nongnu.org, qemu-devel@nongnu.org, Wainer dos Santos Moschetta , Max Reitz , Paolo Bonzini , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 07.01.2020 um 18:43 hat Christophe de Dinechin geschrieben: > > It would break backwards compatibility for "-machine accel=3Dtcg:kvm", > > which so far meant "use TCG if compiled in, otherwise use KVM". This i= s > > not something I would have a problem with... except that "tcg:kvm" is > > the default if no -accel option is provided! >=20 > What is the rationale for picking tcg over kvm? >=20 > My guess is that when this was selected, KVM was the new fancy unstable > thing and this was deemed the safe choice. My other guess is that this wa= s > around 1907 or so :-) My third guess is that you will probably provide me > with a much better rationale ;-) I know I intentionally disabled KVM in the past for debugging guests because TCG allowed a few more things there (most of -d doesn't do anything with KVM, and I think the gdb stub also had some restrictions). Requiring an explicit '-accel tcg' for such cases might be reasonable enough, though. (And if we make this change and therefore break with the habit that Peter mentioned - leaving defaults unchanged - could we make more changes that better reflect a typical use case today? For example, I doubt most people can do with only 128 MB of RAM in the guest.) Kevin