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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA51CC4167B for ; Fri, 1 Dec 2023 15:51:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=DiftojRTF6CRKf7HN0ZFV6BhZIzSTIs8hICaHSZSu74=; b=R81Cvv/Z8p+Nna wcs2hBAvWGb1e+TgZxZwyQNoG42Em5vG8KB0xQOdwiH4dUS9joKO5N78tRZgtAt0Ppr5Zxo4ICfLN HDcWk7Dp0bJnxlyE6ouCWdCf6YjKeDrjHLRs5kx1zW9ZNvUhQsVyKq65MhykJeWfviE2yCUaDpDzT dDZHbadJBiwQRhQCvAJmzEZN0dbmLpZGEHC+vMRpw8dbtIyb3l2dBKUAe3XRuiazsgerabbdwnBaL dfokrQ5jjGc4f5LUAZCM1kwZrXh+YrBtmu1zVIO4QA3poQoUuLLUTb2rDcxB3VQpfh8InaXyBwvXT 7hq+0in7tUEFxz+BcYkQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r95nc-00E5VQ-26; Fri, 01 Dec 2023 15:51:28 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r95na-00E5Uc-0D for kexec@lists.infradead.org; Fri, 01 Dec 2023 15:51:27 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701445885; 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=J7QbH72MaN7zgPPC836wmmvKLt2x8/XmeGRsr2itGo8=; b=EukU37ngN6hwkgbaruOAklX5q5/XIxUPY+uJ5qpQ2HkPjXE1vvzCo0lrZZOo9abexW4hnZ WQfGZMFu982EyIIdCyRHHbgu6HbKh/HAdISDgyMEi5x6aUDFog8fL0PktSqWnPMu+lk7UJ mcjVJ7cyfFiR8yoWH1TZg6HIpqSnasc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-186-fGVmDC1vNfGhqLF9iG1lZQ-1; Fri, 01 Dec 2023 10:51:20 -0500 X-MC-Unique: fGVmDC1vNfGhqLF9iG1lZQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2D5F3831524; Fri, 1 Dec 2023 15:51:17 +0000 (UTC) Received: from rotkaeppchen (unknown [10.39.194.211]) by smtp.corp.redhat.com (Postfix) with ESMTP id C4787492BEF; Fri, 1 Dec 2023 15:51:15 +0000 (UTC) Date: Fri, 1 Dec 2023 16:51:13 +0100 From: Philipp Rudo To: Michal Hocko Cc: Baoquan He , Donald Dutile , Jiri Bohac , Pingfan Liu , Tao Liu , Vivek Goyal , Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/4] kdump: crashkernel reservation from CMA Message-ID: <20231201165113.43211a48@rotkaeppchen> In-Reply-To: References: <91a31ce5-63d1-7470-18f7-92b039fda8e6@redhat.com> <20231201123353.2b3db7fa@rotkaeppchen> Organization: Red Hat inc. MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231201_075126_185381_8F614CE1 X-CRM114-Status: GOOD ( 19.25 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Fri, 1 Dec 2023 12:55:52 +0100 Michal Hocko wrote: > On Fri 01-12-23 12:33:53, Philipp Rudo wrote: > [...] > > And yes, those are all what-if concerns but unfortunately that is all > > we have right now. > > Should theoretical concerns without an actual evidence (e.g. multiple > drivers known to be broken) become a roadblock for this otherwise useful > feature? Those concerns aren't just theoretical. They are experiences we have from a related feature that suffers exactly the same problem regularly which wouldn't exist if everybody would simply work "properly". And yes, even purely theoretical concerns can become a roadblock for a feature when the cost of those theoretical concerns exceed the benefit of the feature. The thing is that bugs will be reported against kexec. So _we_ need to figure out which of the shitty drivers caused the problem. That puts additional burden on _us_. What we are trying to evaluate at the moment is if the benefit outweighs the extra burden with the information we have at the moment. > > Only alternative would be to run extended tests in > > the field. Which means this user facing change needs to be included. > > Which also means that we are stuck with it as once a user facing change > > is in it's extremely hard to get rid of it again... > > I am not really sure I follow you here. Are you suggesting once > crashkernel=cma is added it would become a user api and therefore > impossible to get rid of? Yes, sort of. I wouldn't rank a command line parameter as user api. So we still can get rid of it. But there will be long discussions I'd like to avoid if possible. Thanks Philipp _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec