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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 5B25CC433C1 for ; Fri, 26 Mar 2021 13:30:31 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 1848561A18 for ; Fri, 26 Mar 2021 13:30:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1848561A18 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.101805.194942 (Exim 4.92) (envelope-from ) id 1lPmXa-0006iZ-Cf; Fri, 26 Mar 2021 13:30:18 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 101805.194942; Fri, 26 Mar 2021 13:30:18 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lPmXa-0006iS-9W; Fri, 26 Mar 2021 13:30:18 +0000 Received: by outflank-mailman (input) for mailman id 101805; Fri, 26 Mar 2021 13:30:17 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lPmXZ-0006iN-2b for xen-devel@lists.xenproject.org; Fri, 26 Mar 2021 13:30:17 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 273889a5-b042-458c-80a1-6e63964ca43f; Fri, 26 Mar 2021 13:30:16 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 52C42AB8A; Fri, 26 Mar 2021 13:30:15 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 273889a5-b042-458c-80a1-6e63964ca43f X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1616765415; h=from:from:reply-to: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=kYAGONEfrXOTEzejsd+iopZPq0beT5W/vMevZDvgwvE=; b=K6a31O6ITTv7AtGVyFJyrQGuRAD4kqOl7zWK61o8yzWghrQiJO6YYEmxf+yLyWlCG3sIjG mHeQd41UdWprkNIxPJieGfmY74Bh80/9X1fOnMg6K2uSOT1SY21S157pB0zhfD+3/rQXsD L4hh5pIxeikZb+xgMZOgMkcJHuC316A= Subject: Re: [PATCH v1.1 2/2] x86/hpet: Don't enable legacy replacement mode unconditionally To: Ian Jackson Cc: Andrew Cooper , Xen-devel , Wei Liu , =?UTF-8?Q?Marek_Marczykowski-G=c3=b3recki?= , =?UTF-8?B?RnLDqWTDqXJpYyBQaWVycmV0?= , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= References: <20210325165224.10306-3-andrew.cooper3@citrix.com> <20210325172132.14980-1-andrew.cooper3@citrix.com> <24669.52641.499147.88002@mariner.uk.xensource.com> <24669.54213.173154.400771@mariner.uk.xensource.com> From: Jan Beulich Message-ID: Date: Fri, 26 Mar 2021 14:30:09 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <24669.54213.173154.400771@mariner.uk.xensource.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 26.03.2021 13:29, Ian Jackson wrote: > I wrote: >> I'm sorry, but I think it is too late for 4.15 to do this. I prefer >> Jan's patch which I have alread release-acked. >> >> Can someone qualified please provide a maintainer review for this, >> ideally today ? > > I asked Andrew on IRC: > > 12:08 andyhhp__: Are you prepared to maintainer-ack Jan's > more-minimal hpet workaround approach ? > 12:16 Diziet: honestly, no. I don't consider that > acceptable behaviour, and it is a fairly big "f you" > (this was literally feedback I got in private) to > the downstreams who've spent years trying to get us > to fix this bug, and have now backported the first > version. > 12:16 I'm looking into the feedback on my series > 12:17 one way or another, the moment we enter the fallback > path for interrupt routing, something is very broken > on the system > 12:19 so the tradeoff is an unspecified bug on one ancient > laptop which can't be tested now, vs 5 years of Atom > CPUs, 2 years of latop CPUs, and the forthcoming > Server line of Intel CPUs > 12:19 or whatever other compromise we can work on > > I'm sorry that this bug is going to continue to be not properly fixed. Actually I had another thought here in the morning, but then didn't write it down: While Andrew's approach indeed would (hopefully) improve user experience, it'll reduce the incentive of actually fixing the issue. Normally I might not be that concerned, but seeing how long it took to even arrive at a workaround, I'm afraid now I am concerned. Jan