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=-14.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,NORMAL_HTTP_TO_IP,NUMERIC_HTTP_ADDR, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 9999BC433E0 for ; Mon, 25 Jan 2021 19:12:05 +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 BB7A32067B for ; Mon, 25 Jan 2021 19:12:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BB7A32067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=weilnetz.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56308 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l47HP-0006FK-Hk for qemu-devel@archiver.kernel.org; Mon, 25 Jan 2021 14:12:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:34002) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l474C-0006Uw-ML for qemu-devel@nongnu.org; Mon, 25 Jan 2021 13:58:26 -0500 Received: from mail.weilnetz.de ([37.120.169.71]:33116 helo=mail.v2201612906741603.powersrv.de) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l4749-0006GZ-3M for qemu-devel@nongnu.org; Mon, 25 Jan 2021 13:58:24 -0500 Received: from edv-macbook-pro.fritz.box (p5b1511bf.dip0.t-ipconnect.de [91.21.17.191]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail.v2201612906741603.powersrv.de (Postfix) with ESMTPSA id 1CB54DA0064; Mon, 25 Jan 2021 19:58:18 +0100 (CET) To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= References: <20210125144530.2837481-1-philmd@redhat.com> <20210125144530.2837481-5-philmd@redhat.com> <20210125164746.GE3538803@redhat.com> <992cbe66-dfae-7950-0d92-516b2f0c9717@redhat.com> From: Stefan Weil Subject: Re: [PATCH v4 4/4] meson: Warn when TCI is selected but TCG backend is available Message-ID: <9f22d4b0-34ca-6798-3661-36057609c152@weilnetz.de> Date: Mon, 25 Jan 2021 19:58:18 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <992cbe66-dfae-7950-0d92-516b2f0c9717@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=37.120.169.71; envelope-from=sw@weilnetz.de; helo=mail.v2201612906741603.powersrv.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Paolo Bonzini , Thomas Huth , Richard Henderson , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 25.01.21 um 18:05 schrieb Philippe Mathieu-Daud=C3=A9: > On 1/25/21 5:47 PM, Daniel P. Berrang=C3=A9 wrote: >> On Mon, Jan 25, 2021 at 03:45:30PM +0100, Philippe Mathieu-Daud=C3=A9 = wrote: >>> Some new users get confused with 'TCG' and 'TCI', and enable TCI >>> support expecting to enable TCG. >>> >>> Emit a warning when native TCG backend is available on the >>> host architecture, mentioning this is a suboptimal configuration. >>> >>> Reviewed-by: Stefan Weil >>> Reviewed-by: Thomas Huth >> Nitpick, the text printed is completely rewritten from what they >> reviewed, so I would probably have dropped their R-b for that >> scenario. > I thought about it, and assumed their review tag was for the logical > change of adding a warning, not particularly the warning content. > > I agree this it would have been better to ask them to review again. > Next time I will reset the tags. You are right, I would not have signed that new text and either used the = original text (which was sufficient in my opinion) or used a different on= e: Use of the TCG interpretor is not recommended on this host architecture f= or most users because there is a native TCG execution backend available w= hich provides substantially better performance. I have no evidence that TCI is less reliable than TCG, so I would not=20 write that. And there are people who have good reasons to use TCI. So why should I=20 recommend them to stop that? Stefan >>> Suggested-by: Daniel Berrang=C3=A9 >>> Signed-off-by: Philippe Mathieu-Daud=C3=A9 >>> --- >>> meson.build | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/meson.build b/meson.build >>> index 16b2560e7e7..f675c54e636 100644 >>> --- a/meson.build >>> +++ b/meson.build >>> @@ -228,6 +228,13 @@ >>> else >>> error('Unsupported CPU @0@, try --enable-tcg-interpreter'.for= mat(cpu)) >>> endif >>> + elif get_option('tcg_interpreter') >>> + warning('Use of the TCG interpretor is not recommended on this h= ost') >>> + warning('architecture. There is a native TCG execution backend a= vailable') >>> + warning('which provides substantially better performance and rel= iability.') >>> + warning('It is strongly recommended to remove the --enable-tcg-i= nterpreter') >>> + warning('configuration option on this architecture to use the na= tive') >>> + warning('backend.')