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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 78C35C433B4 for ; Tue, 13 Apr 2021 23:33:24 +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 3529661220 for ; Tue, 13 Apr 2021 23:33:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3529661220 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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.110164.210256 (Exim 4.92) (envelope-from ) id 1lWSWe-00047g-6f; Tue, 13 Apr 2021 23:32:56 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 110164.210256; Tue, 13 Apr 2021 23:32:56 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lWSWe-00047Z-3T; Tue, 13 Apr 2021 23:32:56 +0000 Received: by outflank-mailman (input) for mailman id 110164; Tue, 13 Apr 2021 23:32:55 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lWSWc-00047U-Uz for xen-devel@lists.xenproject.org; Tue, 13 Apr 2021 23:32:54 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 16d6cc9f-0d1b-4a16-974c-979b6c1342d8; Tue, 13 Apr 2021 23:32:54 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 46F1A61222; Tue, 13 Apr 2021 23:32:53 +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: 16d6cc9f-0d1b-4a16-974c-979b6c1342d8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618356773; bh=PDWurdlRjIMbrz/aF4frD96uw6kSwSCdW9WLetMQJ2g=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=eeuhNogG6wddYtSlkqY1kbW3362Mq3rQbyckLffkXQRGwR3+0/CGNRxXsHqetDY0g gqo/fXuPFNghVznGTNPoeKHpQF0syEU9/X7eAk6M9Yn9IiFfqTBybKfhyko1Xzg5uy fsZ3tCNMZNRWcKkP8XLERt66sdgVW5qzihwxFfl6C51q7nmsx//T7vpOKTXCaX47/e HefDbr0C32qp3gGRa3I9Xqy6A2Evo8pLCzrcOnjaY388eYUYJ7hyt85OhiwWMC3W2T PrJkKKWnZRYlkFBH+sGs08UuMdMSwKPbV9F4JJ8bXFVBXx/pWZqnFigbDVJnJ+vZig ig3wvHl9CFjvQ== Date: Tue, 13 Apr 2021 16:32:52 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: Boris Ostrovsky cc: Juergen Gross , "xen-devel@lists.xenproject.org" , Stefano Stabellini Subject: Re: Support of old Xen versions in the Linux kernel In-Reply-To: Message-ID: References: <1e4dc7c0-4364-1095-bb6b-c6341bc58e60@suse.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Tue, 13 Apr 2021, Boris Ostrovsky wrote: > On 4/13/21 2:14 AM, Juergen Gross wrote: > > In x86 kernel development the question came up whether we need to > > support XENFEAT_gnttab_map_avail_bits not being set when running as a PV > > guest. > > > > This feature is active for PV guests since Xen 3.4. > > > > So the basic question is: which is the oldest version of Xen we want to > > support in the Linux kernel? As far as I know there is no Xen based > > product in productive use with Xen older than 4.2. > > > > Would we be fine to drop support for older versions (feel free to > > suggest other versions than 4.2 as the first to be supported Xen > > version)? > > > > In case the answer is yes, I'd post some patches to clean up the kernel, > > including a safety net to bail out in case a feature needed isn't > > available. > > Sounds good to me. For ARM, the Xen ABI became stable only with Xen 4.4.